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Consultant Report

Project Number: 45206-001 September 2020

Nepal: Water Resources Project Preparatory Facility Detailed Engineering Design: Mawa – Ratuwa Basin (Part 1 of 2)

This document is being disclosed to the public in accordance with ADB's Access to Information Policy.

WRPPF: Preparation ofPriority River Basins FloodRisk Management Project,Nepal

Detailed Engineering Design: Mawa – RatuwaBasin

03 October 201915 October 2019

GOVERNMENT OF NEPAL

Ministry of Energy, Water Resources and Irrigation

Department of Water Resources and Irrigation

1243 124 124https://mottmac.sharepoint.com/teams/pj-b1549/Shared Documents/02-Reports/DetailedEngineering Report/To issue 021019/FOR ISSUE/WITHOUT BORDERSTRUCTURES/021019 DED MR - MASTER - V3.0 - FINAL FOR ISSUE.docxMott MacDonald

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WRPPF: Preparation ofPriority River Basins FloodRisk Management Project,Nepal

Detailed Engineering Design: Mawa – RatuwaBasin

15 October 2019

Mott MacDonald Limited. Registered inEngland and Wales no. 1243967.Registered office: Mott MacDonald House,8-10 Sydenham Road, Croydon CR0 2EE,United Kingdom

Mott MacDonald | WRPPF: Preparation of Priority River Basins Flood Risk Management Project, NepalDetailed Engineering Design: Mawa – Ratuwa Basin

383877 | REP | 0055 | 03 October 2019Detailed Engineering Design: Mawa – Ratuwa Basin

Issue and Revision Record

Revision Date Originator Checker Approver Description

0 05/04/19 Consultantsteam

AChoudhury

J Prytherch

C Eller

C Hetmank 1st submission

1 02/08/19 C Eller A.Choudhury

L. Akindiji 2nd submission

2 23/08/19 C Eller A.Choudhury

C Hetmank 3rd submission

3 15/10/19 C Eller AChoudhury

L Akindiji 4rh submission; structures(PRTW.06 L/B and R/B) within theproximity of the Indian borderremoved. Cost estimates for theworks updated with 2019-20

District rates.

Document reference: 383877 | REP | 0055

Information class: Standard

This document is issued for the party which commissioned it and for specific purposes connected with the above-

captioned project only. It should not be relied upon by any other party or used for any other purpose.

We accept no responsibility for the consequences of this document being relied upon by any other party, or being used

for any other purpose, or containing any error or omission which is due to an error or omission in data supplied to us

by other parties.

This document contains confidential information and proprietary intellectual property. It should not be shown to other

parties without consent from us and from the party which commissioned it.

This Re por t has be en p rep are d solely for use by t he p arty w hich c om mission ed it (the 'Client') i n co nnecti on wit h the cap tione d p roject . It s hould not be used for any oth er p urp ose. N o p erso n ot her tha n th e Client or any party who has expr essly a gre ed t er ms of relia nce wit h us (the 'Recipie nt(s )') m ay r ely on the cont ent, info rma tion or any view s exp ress ed in the R epo rt. This R epo rt is co nfide ntial and c ont ains p rop riet ary in tellect ual p rop erty and we ac cept no duty of ca re, resp onsibility or li ability t o any oth er recipi ent o f this R epo rt. N o re pre sent ation , wa rran ty o r un dert aking , exp ress or i mplie d, is made an d no res ponsi bility or liability is acce pted by us to any p arty oth er t han the Cli ent or a ny Reci pient (s), as t o the accu racy or c om plete ness of th e info rm ation cont aine d in t his Rep ort. Fo r t he av oida nce o f do ubt t his Re port do es no t in any way pu rpo rt to includ e a ny leg al, ins ura nce or fin ancial advic e or opini on.



Contents

Executive summary 2

1 Introduction 7

1.1 Project rationale 7

1.2 Objectives of the detailed design report 9

1.3 Purpose of this report 9

2 Mawa – Ratuwa Basin 10

2.1 Location and area 10

2.2 Land use and settlement map 11

2.3 Geology and structure of hill slope catchment 12

2.4 Relief and slope of the upper catchment 14

3 Priority works 17

4 Basis of Development 31

4.1 Introduction 31

4.2 Design strategy 31

4.3 Guidelines and standards 33

4.4 Climate change 34

4.5 Design return period 34

4.6 Design life 34

4.7 Embankment Breach 35

4.8 Freeboard 35

4.9 Lacey’s wetted perimeter 36

4.10 Hydraulic design criteria 39

4.11 Room for river 40

4.12 Survey works 40

5 Detailed design of civil works 41

5.1 Introduction 41

5.2 Embankment Design 41

5.2.1 General description 41

5.2.2 Material parameters 42

5.2.3 Slope stability 43

5.2.4 Design loads 43

5.2.5 Seepage 44

5.2.6 Factor of safety (FOS) and design cases 45

5.2.7 Results 46



5.2.8 Final design 47

5.2.9 Stability under seismic loading 48

5.2.10 Liquefaction of the foundation soil 49

5.2.11 Rockfill drainage area 50

5.2.12 Bearing capacity 50

5.2.13 Construction 51

5.2.14 Tie-ins 51

5.2.15 Repair to existing embankments 52

5.3 Revetments 52


5.3.2 Design 53

5.4 Spurs 54


5.4.2 Design 54

5.5 Launching aprons 55


5.5.2 Design 55

5.6 Toe drain 55


5.6.2 Design 56

5.7 Outlet structures 56


5.7.2 Design 56

5.8 Nature-based solutions 56

5.9 Results DED 57

5.10 Designer’s Hazard Elimination and Management Record 58

6 Maintenance 59

6.1 Introduction 59

6.2 Embankments (earth works) 59

6.3 Revetments, spurs and launching aprons (gabions) 60

6.4 Outlet structures 60

6.5 Embankment failure 61

7 Cost estimates 63

References 64

Appendices 65

A. Hydraulic design criteria 66

A.1 Modelling Results – Run 2 (50 year return period) 66

A.2 Modelling Results – Run 3 (50 year return period) 71

A.3 Comparison modelling results 1 per 50 years return period 77



B. Design calculations 81

B.1 Standards and Guidelines 81

B.2 Slope stability 84

B.3 Revetment, spurs and launching apron 93

B.4 Existing channel drainage design 104

B.5 Toe drain design 107

C. Bill of Quantities and cost estimates 110

D. Design drawings 111

D.1 Location priority works 111

E. Designer’s Hazard Elimination and Management Record 113

Mott MacDonald | WRPPF: Preparation of Priority River Basins Flood Risk Management Project, Nepal 1Detailed Engineering Design: Mawa – Ratuwa Basin


List of abbreviations

ADB - Asian Development Bank

BoQ - Bill of Quantities

CBS - Central Bureau of Statistics

DED - Detailed Engineering Design

DEM - Digital Elevation Model

DMG - Department of Mines and Geology

DPR - Detailed Project Report

DWIDM - Department of Water Induced Disaster Management

DWRI - Department of Water Resources and Irrigation

FHRMP - Flood Hazard Mapping and Risk Management Project

FS - Feasibility Study

GoN - Government of Nepal

LS - Lower Siwaliks

masl - Meters above sea level

MEWRI - Ministry of Energy, Water Resources and Irrigation

MS - Middle Siwaliks

MS1 - Middle Siwaliks lower

MS2 - Middle Siwaliks upper

NPR - Nepalese Rupee

PEP - People Embankment Programme

PRTW - Proposed River Training Works

Q - Discharge

RCP - Representative Concentration Pathways

US - Upper Siwaliks

USD - Unites States Dollar

VAT - Value Added Tax

WL - Water level

WRPPF - Water Resources Project Preparatory Facility



Executive summary

Nepal is considered one of the most disaster-

prone countries in the world. Alongside other

natural hazards, such as earthquakes and

landslides, flooding poses a recurrent risk to

large sections of the population. Flooding has a

particular impact on communities residing in the

Terai region (figure indicates affected areas

during the monsoon in August 2017). The Terai

region occupies approximately 17% of the

country and is seen as the granary of Nepal.

Agriculture in the Terai region is the basis of the

economy in Nepal with major crops such as

rice, wheat, pulses, sugarcane, jute, tobacco and maize. The Terai region has a long history of

floods affecting farmland, crops and livestock, which affect lives, livelihoods and property of poor

communities as well as important infrastructure such as embankments, roads, communication

infrastructure and power supply, and all significantly impacting development.

Acknowledging the importance of the Terai region to Nepal, the Government of Nepal, through

the Ministry of Energy, Water Resources and Irrigation, is implementing the ‘Priority River

Basins Flood Risk Management Project’ in the Southern Nepal Terai region, which is supported

by the Asian Development Bank (ADB). The project is the continuation of the pre-feasibility study:

Package 3: Flood Hazard Mapping and Risk Management Project. The project includes the

following river basins:

1. Mohana – Khutiya basin;

2. Mawa – Ratuwa basin;

3. Lakhandei basin;

4. West Rapti basin;

5. East Rapti basin;

6. Bakraha basin.

This detailed design report, prepared by Mott MacDonald (the Consultant), concerns the Mawa –

Ratuwa Basin, which is located in the east of Nepal. The works comprise the detailed design of

the structures identified during the feasibility study of Mawa – Ratuwa Basin.

The Mawa – Ratuwa Basin, located in the east of Nepal in the Terai region (see figure below), is

severely affected by floods causing damage to communities, agriculture, public infrastructure. For

sustainable development and to mitigate flooding in the Mawa - Ratuwa Basin, structural

measures are required.

During the feasibility study, preliminary designs were prepared and the economic viability of the

investments were confirmed. The preliminary designs and the discussions held with the WRPPF

and the ADB are the basis for the preparation of the detailed engineering designs, which are

described in this detailed design report. The objectives are to provide detailed information such

as drawings and Bill of Quantities that is required for the tender documents.



During the feasibility study, the feasibility of the investments of the structures to be constructed

within the scope of this project was assessed and concluded to be feasible. The selected priority

works are shown in the figure below. It was agreed with DWRI during the ADB Mission in July

2019 that embankments within the proximity of Indian border, i.e. PRTW.06 L/B and R/B would

be removed from the works package.



It is evident that the Detailed Engineering Designs highly depend on the design criteria adopted.

In summary:

- When preparing the Detailed Engineering Designs the following design aspects were

taken into account: a) Sustainability, b) Environmentally friendly (bio-engineering), c)

Adaptability, and d) Low cost solutions;

- The designs are carried out using appropriate Nepalese Standards and Guidelines for

the design of river training works. If Nepalese Standards and Guidelines are not available,

international standards that are commonly used in Nepal will be applied;



1 Introduction

1.1 Project rationale

Nepal is considered one of the most disaster-prone countries in the world. Alongside other natural

hazards, such as earthquakes and landslides, flooding poses a recurrent risk to large sections of

the population. Nepal, with over 6,000 rivers, is very rich in water resources, which provides both

positive as well as negative impacts to the country. The hydrology in Nepal is primarily monsoon

driven with approximately 85% of the yearly rainfall during the monsoon period from June –

September. During this period the rainfall and runoff is very high, resulting in floods.

Flooding has a particular impact on communities residing in the Terai region. The Terai region

occupies approximately 17% of the country and is seen as the granary of Nepal. Agriculture in

the Terai region is the basis of the economy in Nepal with major crops such as rice, wheat, pulses,

sugarcane, jute, tobacco and maize. The topography is generally flat with a gentle slope in

southward direction. Rivers originating from the mountain and hill areas run through the Terai

region in southwards direction and eventually into neighbouring India.

The Terai region has a long history of floods affecting livelihoods and agriculture. Figure 1 shows

the large number of districts that were affected by floods during the monsoon in August 2017.

Figure 1: Monsoon affected districts 11-13 August, 2017 (source: reliefweb.int)



Besides inundating the land, the floods also transport large quantities of sediment, gravel and

boulders due to the excessive soil erosion in the upstream hill areas (e.g. due to landslides and

gully erosion). Due to the steep gradient in the hill areas, floods transport such material in the

downstream direction towards the Terai region, where due to the gentle slope the material will

deposit. The deposit of material occurs:

- In the river itself, increasing the river bed level, decreasing the discharge capacity and

thus increasing the flood risks;

- On farmland, negatively affecting agricultural livelihoods and food production.

At several locations, floods cause severe bank erosion, threatening the destruction of settlements,

agricultural land and infrastructure.

The floods in the Terai region damage farmland and crops and kill livestock, which is of critical

importance to the lives, livelihoods and property of poor communities as well as damaging

important infrastructure such as embankments, roads, communication infrastructure and power

supply, and all significantly impacting the development of the region. With the Terai region being

the granary of Nepal, the floods not only negatively impact on the Terai region but the country as

a whole.

Flood risks are likely to increase in the Terai region as a result of high population growth, increase

in urban and infrastructure development as well as due to the impact of climate change in general

and changing rainfall patterns in particular.

Acknowledging the importance of the Terai region to Nepal, the Government of Nepal (GoN),

through the Ministry of Energy, Water Resources and Irrigation (MoEWRI), is implementing the

‘Priority River Basins Flood Risk Management Project’ in the Southern Nepal Terai region,

which is supported by the Asian Development Bank (ADB). The project is the continuation of the

pre-feasibility study: Package 3: Flood Hazard Mapping and Risk Management Project

(FHRMP). During the pre-feasibility study of the 102 flood prone rivers that flow into the Terai

region, 25 river basins were studied.

Mott MacDonald, as appointed by the MEWRI, executes this ‘Priority River Basins Flood Risk

Management Project’, which will draw on the findings of the pre-feasibility study. The key

requirements for this project is to ensure that cost beneficial and sustainable infrastructure

interventions are robustly identified, duly considering the environmental and social impacts, both

positive and negative, that flood protection interventions and river training works can have. The

basins included in the ‘Priority River Basins Flood Risk Management Project’ are:

- Mohana – Khutiya basin;

- Mawa – Ratuwa basin;

- West Rapti basin;

- Lakhandei basin;

- East Rapti basin;

- Bakraha basin.

The locations of all sub-projects are shown in Figure 2.

This detailed design report, prepared by Mott MacDonald (the Consultant), concerns the Mawa –

Ratuwa basin, which is located in the east of Nepal. The works comprise the detailed design of

the structures identified during the feasibility study of Mawa – Ratuwa Basin. 1

1 Feasibility Study: Mawa – Ratuwa, Package 7: WRPPF: Preparation of Priority River Basins Flood Risk Management Project, Nepal,Mott MacDonald, 2019



Figure 2: Location of sub-projects

1.2 Objectives of the detailed design report

During the feasibility study, preliminary designs were prepared and the economic viability of the

investments were confirmed. The preliminary designs and the discussions held with the WRPPF

and the ADB are the basis for the preparation of the detailed engineering designs (DED), which

are described in this detailed design report. The objectives of the DED is to provide detailed

information such as DED drawings and Bill of Quantities (BoQ) which will be included in the tender

documents.

1.3 Purpose of this report

The purpose of this report is to provide DED related to the investments for the Mawa – Ratuwa

Basin as constructed within the scope of this project, which will be input in the tender documents.

The outline of the report is as follows:

Chapter 2 Provides a description of the Mawa – Ratuwa Basin

Chapter 3 Provides an overview of the viable structures from the feasibility phase

Chapter 4 Provides an overview of the Basis of Development, which includes

design criteria

Chapter 5 Describes the results of the DED including BoQ

Chapter 6 Provides a description of the maintenance works of the civil works

Chapter 7 Describes the cost estimations



2 Mawa – Ratuwa Basin

2.1 Location and area

The catchment of the Mawa - Ratuwa river basin lies between Northing 2919087 m to 2973609

m (latitude 26°25′ 56.89″–26°49′ 05.14″N), and between Easting 561528 m to 580023 m

(longitude 87°36’36.31″E–87°47′24.97″E) in WGS 84, UTM Zone 45 N (see Figure 3).

Figure 3: Mawa - Ratuwa basin location map



The basin extends from Chure Hills (Siwalik Hills, also known as sub-Himalayan hills, at low

altitude) in the North and in Terai in the south up to the Nepal - India border. Ratuwa is the main

water body, which is joined by the Mawa in the West, and Bidhawa and Chanju Khola in the East.

The catchment covers an area of 413 km2 is located in the East of Nepal (Figure 3). The Mawa -

Ratuwa basin shares the districts of Morang and Jhapa, both in Province No. 1. The basin has

366 settlements distributed over rural and urban municipalities with a population of 165,260 and

36,871 households (CBS, 2011). Damak and Urlabari are the two major towns located in this

catchment.

2.2 Land use and settlement map

Land use map and statistics for this basin were extracted from the land use of the Chure Terai -

Madhesh Area prepared by Chure Terai Madhesh Protection and Management Master Plan

(2016). The basin has two distinct characteristic land use patterns in the upper and in the lower

catchment (Figure 4).

The upper catchment has dominant non-agricultural land use types, such as forest, shrub and

grass, dominating more than 85% of the total area. Human disturbance in terms of agriculture

appears low in the upper catchment. This indicates that the ecology is least disturbed. Therefore,

the impact of land use on sediment production is expected to be low. However, the deforestation

and the overgrazing on the steep areas could induce erosion.

The lower catchment has dominant agricultural land use and built-up areas comprising 87% of

the total area, whereas forest, shrub and grass cover account only for 11%.

In the upper alluvial reach of the Mawa and Ratuwa River (gravel and sand zone), the riverine

forest stretches along 3.34 and 1.8 km respectively. Similarly, in the middle reach (sand and silt

zone), the riverine forest stretches along about 5.36 and 11.7 km of the Mawa and Ratuwa

sections respectively. This riverine forest has been developed or restored by local people

wherever land was available to check bank erosion and flood. In the remaining length, Mawa and

Ratuwa river banks are exposed either to cultivated land or settlements, except for barren areas

in channel scroll or migration areas.

Much of the agricultural land in the Mawa - Ratuwa basin is located in the flood plain zone, which

lies south to the piedmont belt “Bhabar“ and in the Terai. Bhabar is the region South of the Lower

Himalayas and the Siwalik Hills, while Terai is low land further to the South. It is in fact the alluvial

apron of sediments washed down from the Siwaliks along the northern edge of the Indo-Gangetic

Plain. Here, forest except for grassland, virtually does not exist along the bank corridor. Hence

flood and bank erosion hazard as well as risk of loss of land and damage to the properties is high.



Source: Mott MacDonald derived this map from Chure Terai Madhesh Protection and Management Master Plan (2016)

Figure 4: Land use map of Mawa - Ratuwa basin

2.3 Geology and structure of hill slope catchment

The Mawa - Ratuwa basin is underlain by the Siwaliks, the youngest parallel mountain chain in

the Himalayan orogen (Gansser, 1964) in the North, and by Terai, made of quaternary deposits



in the South. The Siwalik Ranges from the most tectonically active Himalayan belt, which has

resulted in active deformation, dislocation and uplift of rocks, giving rise to a complex geologic

structure and unstable and erodible landscape (Nakata, 1989; Lavé and Avouac, 2001).

Based on lithological characteristics DMG (2007), three broad categories of the Siwalik rocks, i.e.,

Upper Siwalik (US), Middle Siwaliks (MS) and the Lower Siwaliks (LS) are found (Figure 5).

The US is composed of conglomerates, sandstone and few mudstone beds. This unit is divided

into a lower and upper member. The lower member is represented by well sorted, pebble- and

cobble-conglomerate associated with reddish brown sandstone and dark grey mudstone. The

clasts of the conglomerate are rounded to sub-rounded and show slight increase in size toward

the younger succession. The upper member is characterised by unsorted loose, boulder-sized

conglomerate with grey sandstone and mudstone. This unit contains typically the Siwaliks

sandstone boulders

The Lesser Himalayan rocks in the study area are represented by the Dubidanda Formation,

which consist of greenish grey quartizite with chloritic phylitte and augen gneiss. The rocks are

massive but with open cracks and joints. The rocks are moderately weathered.

The MS is comprised of fine to very coarse-grained sand as well as pebbly sandstone, which

alternate with mudstone. The proportion of sandstone beds is higher than that of the mudstone.

The proportion and coarseness of the sandstone increases towards the upper formation of the

MS. The lower member (MS1) is comprised of fine to coarse grained sandstone interbedded with

mudstone. The upper member of the Middle Siwaliks (MS2) contain pebbly sandstone inter-

bedded with mudstones (DMG 2007). The southern of the upper catchment is made of MS.

The LS consists of an interbedding of mudstone and sandstone. The mudstone is variegated dark

grey in colour (Gorkhali 2001). The sandstones are fine to coarse grained, and are thin to thickly

bedded. The proportion of mudstone is greater than that of sandstone in aggregate. The LS

occupies the upper part of the catchment, which is delineated by a local thrust.

Quaternary Terai consist of recent and post Pleistocene alluvial deposits brought by the rivers

draining the upper catchments of Chure hills and other Himalayan belts, which form a piedmont

(foot hill parts made of alluvial fans) adjacent to the Chure Hills and a flood plain towards the

South comprising the sand and silt deposits. The deposits consist of very coarse (boulders and

cobbles) to fine sediments (sand, silt and clay). The proportion if finer sediments on bank and

river bed increases, in general, with decreasing river gradient and velocity towards the South from

the foothills (LRMP 1986, Dhital 2016).

The Siwaliks is delineated as in Figure 5 from alluvial deposits of the Terai plain by the Main

Frontal Thrust (MFT) in the South. It is the most active frontal fault where the LS are thrust over

the alluvium in the piedmont zone (Nakata, 1989). Similarly, an imbricate thrust of Main Churiya

Thrust runs South East-North West in the northern part of the hill catchment. Both thrusts dip 25°–

30° North East to North East. Bedrocks generally dip towards North East with an amount of 30-

70 (DMG 2007).



Source: Mott MacDonald (DMG, 2007)

Figure 5: Geology and structure of hill slope catchment in Mawa - Ratuwa basin

2.4 Relief and slope of the upper catchment

Based on the analysis of elevation contours derived from the Digital Elevation Model (DEM)

(Survey Department, 2002), the relief of the catchment of the Mawa - Ratuwa river basin ranges



between 169 and 2,081masl. The average relief is 593masl. The highest point lies in the

Mahabharata Range.

The average slope of the upper catchment is 29.15o; such steep slope indicates high potential for

erosive and erodibility in a fragile geological setting. The slope of the upper catchment is

predominantly steep, i.e., the area above 25o slope is about 79.3 %. The slope gradient of Mawa

– Ratuwa basin is shown in Figure 6.

Source: Mott MacDonald derived this map from Chure Terai Madhesh Protection and Management Master Plan (2016)

Figure 6: Slope of Mawa - Ratuwa basin



The gentle slopes (<5o) occupy only 69.3% of the total catchment area (both upper and lower).

Cultivation above 25o is not desirable due to the unstable slopes of Chure hills. The sub catchment

wise statistics of slope gradient is presented in Table 1.

Table 1: Slope gradient Mawa – Ratuwa basin

Slope [deg]

Percent area [%] Weighted averageslope [%]

Total area[km2]

< 5 5-15 15-25 25-30 30-45 >45

Upper catchment 3.5 23.1 32.4 17.3 39.7 22.3 29.15 131

Lower catchment 100 0 0 0 0 0 - 281

Source: Mott MacDonald (Derived from Survey Department, 2002 DEM



3 Priority works

Under the Feasibility Study (FS)2 of Package 7 project, potential locations for structural

interventions have been prioritised. The main inputs to location prioritisation are (i) FHRMP

Package 3 (pre-feasibility), (ii) the DPRs, (iii) site visits, (iv) flood mapping and (v) discussions

with knowledgeable Government staff.

During the FS, the feasibility of the investments of the structures to be constructed within the

scope of this project was assessed and concluded to be feasible. The selected priority works are

shown in Figure 7 (location)and Table 2 (description). It was agreed with DWRI during the ADB

Mission in July 2019 that embankments within the proximity of Indian border, i.e. PRTW.06 L/B

and R/B would be removed from the work package financed by ADB loan. It should be noted that

the hydraulic modelling has been undertaken with PRTW.06 L/B and R/B, assuming that they will

be constructed by the Government in a separate package. No further modelling has been done

following the removal of these embankments.

2 Feasibility Study: Mawa – Ratuwa, Package 7: WRPPF: Preparation of Priority River Basins Flood Risk Management Project, Nepal,Mott MacDonald, 2019



Figure 7: Location selected priority works; Note that this includes embankments (PRTW.06L/B and PRTW.06 R/B that were removed from the package due to proximity to the Indianborder



Table 2: Details of selected priority works

Symbol / overview (indicative) Details

PRTW.01 (a) River: Ratuwa

Start structure

Latitude 26°33'1.75"N

Longitude 87°38'50.01"E

End structure



Chainage *1

Upstream [m] 18,453.7

Downstream [m] 18,245.7

Description:

Located along the left bank providing protection against erosion and inundation. Structures:

· Earthen embankment protected by a gabion revetment. The total length is 420 m;

· The new embankment will tie with existing bridge at the upstream end and natural groundat the downstream end.

· The countryside slope will be strengthened by rockfill, toe drain and grass plantation andseeding (bio-engineering / environmentally friendly). Also, the river side slope will beprotected by grass planting and seeding above the design water level;

· A toe drain is specified, discharging into tributary

· An access road for inspection will be provided at the embankment crest;

· 7 spurs;· Launching aprons to protect the toe of the revetment and spurs.

PRTW.01 (b) River: Ratuwa

Start structure



End structure



Chainage *1



Description:

Located along the left bank providing protection against inundation and erosion. Structures:

· Earthen embankment protected by a gabion revetment. The total length is 1,780 m;

· The new embankment will tie with natural ground at the upstream end and existingembankment at the downstream end.


· The toe drain will include cross-drainage culverts under the earth embankment asindicated in drawings. The culvert will include a trash screen and a penstock at the country



Symbol / overview (indicative) Detailsside and a flap gate at the riverside with associated gabion mattress for the river bed andbank erosion protection at drainage outlet locations;

· An access road for inspection will be provided at the embankment crest;· 10 spurs;

· Launching aprons to protect the toe of the revetment and spurs.

PRTW.02 River: Mohana

Start structure



End structure



Chainage *1



Description:

Located along the right bank providing protection against inundation and erosion. Structures:

· Earthen embankment protected by a gabion revetment. The total length is 825 m;· The new embankment will tie with natural ground at the upstream end and bridge

foundation at the downstream end.


· The toe drain will include cross-drainage culverts under the earth embankment asindicated in drawings. The culvert will include a trash screen and a penstock at the countryside and a flap gate at the riverside with associated gabion mattress for the river bed andbank erosion protection at drainage outlet locations;


· 14 spurs;· Launching aprons to protect the toe of the revetment.

PRTW.03 River: Mawa

Start structure



End structure



Chainage *1





Symbol / overview (indicative) DetailsDescription:


· Earthen embankment protected with a gabion revetment. The total length is 535 m;· The new embankment will tie with natural ground at the upstream end and existing

embankment at the downstream end.




· 9 spurs;· 1 outlet structure;

· Launching aprons to protect the toe of the revetment.

PRTW.04 River: Mawa

Start structure



End structure



Chainage *1



Description:

Located along the right bank providing protection against erosion and inundation. Structures:

· Earthen embankment protected with a gabion revetment. The total length is 785 m;

· The new embankment will tie with existing embankment at the upstream end and existingembankment at the downstream end.




· 15 spurs;

· 1 outlet structure;· Launching aprons to protect the toe of the revetment and spurs.




PRTW.05 (a) River: Mawa

Start structure



End structure



Chainage *1



Description:

Located along the right bank providing protection against erosion and inundation. Structures:

· Gabion revetment only in the first 200 m followed by Earthen embankment protected witha gabion revetment in the next 270 m. The total length of the structure is 470m;

· The new embankment will tie with natural ground at the upstream end and natural groundat the downstream end.





PRTW.05 (b) River: Mawa

Start structure



End structure



Chainage *1



Description:


· Earthen embankment protected with a gabion revetment. The total length is 250 m.· The new embankment will tie with natural ground at the upstream end and existing








· 8 spurs;


PRTW.07 River: Mawa

Start structure



End structure



Chainage *1



Description:



· The new embankment will tie with natural ground at the upstream end and bridge at thedownstream end.




· 17 spurs;





PRTW.08 River: Ratuwa

Start structure



End structure



Chainage *1



Description:


· Earthen embankment protected by a gabion revetment. The total length is 1,330 m;· The new embankment will tie with planned embankment at the upstream end (under

construction) and bridge foundation (under construction) at the downstream end.





PRTW.09 (a) River: Ratuwa

Start structure



End structure



Chainage *1



Description:


· Only gabion revetment protecting existing bank. The total length is 205 m;· 8 spurs;





PRTW.09 (b) River: Ratuwa

Start structure



End structure



Chainage *1



Description:


· Only gabion revetment protecting existing bank. The total length is 820 m;


PRTW.09 (c) River: Ratuwa

Start structure



End structure



Chainage *1



Description:


· Earthen embankment protected by a gabion revetment. The total length is 950 m;· The new embankment will tie with existing embankment at the upstream end and existing









PRTW.09 (d) River: Ratuwa

Start structure



End structure



Chainage *1



Description:








PRTW.10 River: Mawa

Start structure



End structure



Chainage *1

Upstream [m] 38,430


Description:



· The new embankment will tie with existing embankment at the upstream end and naturalground at the downstream end.







· 7 spurs;


PRTW.11 River: Mawa

Start structure



End structure



Chainage *1



Description:

Located along the right bank providing protection against inundation and erosion. Structure:

· Gabion revetment only in the first 105 m followed by Earthen embankment protected witha gabion revetment in the next 545 m. The total length of the structure is 650 m;

· The new embankment will tie with natural ground at the upstream end and existingembankment at the downstream end.




· 10 spurs;





PRTW.12 (L/B) River: Ratuwa

Start structure



End structure



Chainage *1


Downstream [m] 31,380

Description:

Located along the left bank providing protection against inundation and erosion. Structure:

· Earthen embankment protected by a gabion revetment. The total length is 500 m;· The new embankment will tie with existing embankment at the upstream end and natural

ground at the downstream end.





PRTW.12 (R/B) River: Ratuwa

Start structure



End structure



Chainage *1



Description:


· Earthen embankment protected by a gabion revetment. The total length is 500 m;· Above the design water level, the outer slope will be protected by using grass (bio-

engineering / environmentally friendly). Also the crest and inner slope will be protected byusing grass;

· 6 spurs;





PRTW.13 (L/B) River: Mawa

Start structure



End structure



Chainage *1



Description:



· The new embankment will tie with existing embankment at the upstream end and naturalground at the downstream end.




· 5 spurs;


PRTW.13 (R/B) River: Mawa

Start structure



End structure



Chainage *1


Downstream [m] 32,070

Description:





· The toe drain will include cross-drainage culverts under the earth embankment asindicated in drawings. The culvert will include a trash screen and a penstock at the country



Symbol / overview (indicative) Detailsside and a flap gate at the riverside with associated gabion mattress for the river bed andbank erosion protection at drainage outlet locations;





4 Basis of Development

4.1 Introduction

It is evident that the DED highly depend on the design criteria adopted. During the FS phase

discussions were held with WRPPF and ADB regarding the criteria to be adopted. The Basis of

Development for the preparation of the DED is described below.

4.2 Design strategy

When preparing the DED the following design aspects were taken into account:

- Sustainability;

- Environmentally friendly (bio-engineering);

- Adaptability;

- Low cost solutions.

Sustainability

It is important that the structures are sustainable. It must be avoided that the structures fail after

one flood season. This requires that the implemented structures should be designed

appropriately. Concerning embankments, possible overtopping or excessive rainfall can cause

erosion / damage to the crest and / or inner slope of the embankment, which could result in failure

of the embankment. To avoid this, besides protecting the outer slopes, also the crest and the

inner slopes should be protected. Sufficient freeboard should be applied to compensate possible

increasing bed levels due to aggradation and changes in climate change projections. is also

important, from a sustainability point of view, to make use of local available materials, which also

benefits the maintenance works.

Environmentally friendly (bio-engineering)

The structures must have sufficient resistance and height to mitigate the impact of floods but

should also become an integrated part of the surrounding landscape. Large areas of the Mawa –

Ratuwa basin have a rural character. To integrate the structures into the landscape it is preferred

to include environmentally friendly solutions (bio-engineering) into the designs. An

environmentally friendly solution is to integrate e.g. Vetiver or other grasses into the design.

Grass such as Vetiver grass is implemented in different countries to protect the embankments

(bank stabilisation) against floods and is also available in the Terai region. The root system of

Vetiver grass is finely structured and very strong which stabilises the soil making the

embankments resistant against the flood waters.

Environmentally friendly solutions also have the advantage that they decrease the quantities of

required construction materials, which results in lower construction costs.

Environmentally friendly solutions are already implemented in the Terai region, see Figure 8.



Figure 8: Example of environmentally friendly embankment (bio-engineering)

Adaptability

Due to the uncertainties in e.g. climate change and hydraulic boundary conditions it is important

that the structures should be adaptable to future changes. When required, the crest level of the

structure should be able to be increased to cope with future changes. For instance, adding

another layer of e.g. gabions of soil on top of the existing structure.

Low-cost solutions

Budgets are limited while many areas in the basin require protection against erosion and / or

flooding. To minimise the costs, it is important to make use of local available materials. Materials

such as (reinforced) concrete are more expensive compared to local available materials. This

also benefits the maintenance works. Examples of low cost solutions are shown in Figure 9.



Figure 9: Low-cost solutions bamboo porcupine (left) or nylon bags filled with sand to beused as spur (right)

The problem with these low-cost solutions is that the design life time is short to approximately 2 -

4 years.

Making use of local material also concerns the use of boulders. Large quantities of materials

(especially boulders) are excavated from the river bed and transported to different construction

sites, Figure 10.

Figure 10: Mawa – Ratuwa river bed used as quarry

Due to the local availability and lower costs compared to other construction materials, structures

designed and constructed by the People Embankment Programme (PEP) field office engineers

include mainly the use of gabions filled with suitable material excavated from the river bed.

4.3 Guidelines and standards

The DED is carried out using appropriate Nepalese Guidelines for the design of river training

works. The Government of Nepal’s Flood Control and Management Manual, June 2019 has been

used as general guidance document for the design.

Where Nepalese Standards and Guidelines were not available, international standards that are

commonly used in Nepal were applied. These guidelines were supplemented by further

international guidelines.

The primary Standards and Guidelines adopted for the DED are;

· DWIDM Pocket Diary 2071 (2014 / 2015);

· Guidelines for preparation of DPR for flood management works, Government of India

Central Water Commission (2018);



· Handbook for Flood Projection, Anti Erosion and River Training Works, Government of

India Central Water Commission (2012)

Additional Standards and Guidance documents were reviewed during the design process guided

the design include;

· River and channels revetments, a design manual. Escarameia M (1998)

· Technical Standards and Guidelines for Planning and Design, Volume I – Flood Control, JICA

(2002)

· IS 12094, Guidelines for Planning and Design of River Embankments, Bureau of Indian

Standard (2000)

· EM 1110-2-1902 Engineering and Design; Slope Stability, U.S. Army Corps of Engineers

(USACE) (2003)

·

Appendix B.1 documents the Standards and Guidelines that were used for the specific aspects

of the design.

4.4 Climate change

Nepal is a highly vulnerable country to climate change. Change in rainfall patterns, incidence of

frequent droughts, floods and heat waves, and the rapid melting of glaciers are major risks in the

country. The increase of extreme events such as high intensity rains, can result in an increase of

flood events and associated negative impacts.

For sustainable development, the impact of climate change must be included in the design and

modelling works.

For details, reference is made to the report River Hydrology Assessment: Mawa – Ratuwa Basin.3

Within this project the RCP4.5 scenario is implemented. The RCP4.5 climate change projections

for rainfall are integrated into the hydrological model. The output of the hydrological model,

discharges, are input for the hydrodynamic model, which is used to define the design criteria for

the different structures.

The projected time horizon for climate change is the year 2100, which was also used for FHRMP.

4.5 Design return period

For the DED a return period of 1 in 50 years including the impact of climate change was be used.

4.6 Design life

The minimum design life time of structural interventions is 25 years as agreed with the DWRI.

This aligns with the DPR prepared for the basin by the department, which takes into the economic

life of the project as 25 years. However, with good workmanship during construction with a robust

maintenance and repair regime, this service life of the proposed embankment can easily be

extended beyond the design life.

3 River Hydrology Assessment: Mawa – Ratuwa, Package 7: WRPPF: Preparation of Priority River Basins Flood Risk ManagementProject, Nepal, Mott MacDonald, 2019



It should be noted that a 1 in 50 year event has 40% chance of occurring over the structure design

life of 25 years4.

4.7 Embankment Breach

The risk to public safety following an embankment failure have been considered. As outlined in

Section 4.11, the increase in water level following the proposed structures is below 0.3m, hence

the incremental risk posed by the new embankments could be considered as low. However, if the

embankment was to fail, the resulting flood flows onto the adjacent land would be worse than the

original flooding in regard to onset time and velocity. The impact – loss of life and damage to the

land – could be higher.

This risk must be managed by thorough inspection and maintenance procedures. In floods greater

than the design flood (noting that the freeboard will provide some increased protection),

overtopping of the embankments will occur. The design of the early warning system should take

this into account and provide adequate warning if overtopping is expected to occur.

4.8 Freeboard

Freeboard, the distance between the design water level and crest level, is required in order to:

- Compensate for uncertainties in the hydraulic boundary conditions;

- Accessibility of the areas during high water;

- Prevent wave overtopping.

There is not a specific value or international agreed value to be used for freeboard. It also depends

on the local conditions. Different guidelines provide different values for freeboard as can be seen

in Table 3.

Table 3: Indications for freeboard

No Source Criteria Freeboard

1 DWIDM Pocket Diary 2071 - 1.0 – 1.5 m

2 Guidelines for preparation of DPR for

flood management works, India *1

Q < 3,000 m3/s 1.5 m

Q > 3,000 m3/s 1.8 m

3 Technical Standards and Guidelines

for Planning and Design, Volume I –

Flood Control, JICA

Q < 200 m3/s 0.6 m

200 m3/s < Q < 500 m3/s 0.8 m

500 m3/s < Q < 2,000 m3/s 1.0 m

2,000 m3/s < Q < 5,000 m3/s 1.2 m

5,000 m3/s < Q < 10,000 m3/s 1.5 m

Q > 10,000 m3/s 2.0 m

*1: Applied in FHRMP

The maximum design discharge in Mawa – Ratuwa is below 3,000 m3/s (Q50,max = 1,494 m3/s).

Based on Table 3, it can be seen that freeboard in the range of 1.0 – 1.5 m should be selected.

4 US Dept of Commerce- National Oceanic and Atmospheric Administration - National Weather Service. Accessed online[https://www.weather.gov/epz/wxcalc_floodperiod]



The following was analysed to give further confidence in this value;

● Using the guide Accounting for residual uncertainty: an update to the fluvial freeboard guide,

Environment Agency (2017), a rapid analysis was undertaken to ascertain what freeboard the

guide recommends, based on the accuracy and confidence in the local applicability of the

modelling. The exercise involves scoring the reliability of various modelling related elements,

resulting in an overall confidence rating of between 1 and 5 stars. This rating then gives the

resulting freeboard required (either a minimum depth or a proportion of the design flood depth).

A rapid conservative analysis gave a score of 2 stars, resulting in a recommended freeboard

of 1.73m for the highest embankment (5.95m) in the two detailed design basins. As a

comparison, for the highest embankment a 3 star score would give a freeboard of 1.15m and

a 1 star score (the worst possible) would give a freeboard of 2.3m. Based on this range, it was

decided that the proposed freeboard range of 1.0 – 1.5m is acceptable.

● Super-elevation was estimated for three of the tightest bends across the two detailed design

basins (including PRTW.07 for Mawa - Ratuwa) using guidance in Hydraulic Design of Flood

Control Channels; Engineer Manual 1110-2-1601 USACE (1994). Based on velocity and

Froude numbers produced by the hydraulic modelling previously, the difference in water level

between the two banks was calculated. This was then halved to give the increase in water

surface on the outer bend. The results were all below 0.15m (0.5ft) which in the USACE

manual is the acceptable threshold for not increasing the freeboard.

Within this project the possibility was discussed to have a variable freeboard depending on the

location of the structures. For certain areas smaller freeboard can be employed, e.g. but not

limited to:

- At those locations where the structures are easily adaptable to future changes;

- Depending on the land that is being protected, e.g. agriculture or settlements;

- For areas where future sedimentation is anticipated.

A site-by-site analysis of the freeboard for Mawa - Ratuwa Basin was be made. General approach

as adopted within this project are:

- Freeboard of 1.5 m at those locations with larger settlements;

- Freeboard of 1.0 m at those locations where the main area to be protected is

agriculture.

Note that the above assessment was based on the land use type as seen during site visits in

2018 and a review of aerial image later. Any settlements or newly built houses adjacent to the

river after 2018 are excluded from the freeboard assessment criteria.

4.9 Lacey’s wetted perimeter

In Nepal the width of the river is often related to the Lacey’s wetted perimeter, which is used for

alluvial rivers. Within the project area, this mainly concerns the area downstream of the East –

West Highway. Upstream the East – West Highway, the bed material is course consisting of

boulders and gravel. Table 4 shows some examples of guidelines to define the required width of

the river.



Table 4: Indications of required river width

No Source Criteria River width *2

1 DWIDM Pocket Diary 2071 Lacey’s wetted perimeter (P) 3 – 6 x P

2 Guidelines for preparation of DPR

for flood management works, India*1

Lacey’s wetted perimeter (P) 3 x P

3 Technical Standards and

Guidelines for Planning and

Design, Volume I – Flood Control,

JICA

Q = 300 m3/s 40 – 60 m

Q = 500 m3/s 60 – 80 m

Q = 1,000 m3/s 90 – 120 m

Q = 2,000 m3/s 160 – 220 m

Q = 5,000 m3/s 350 – 450 m*1: Applied in FHRMP*2: Distance between flood embankments

The values indicated in Table 4 are guidelines. In the DPR of Lakhandei river basin use is made

of 2 times the Lacey’s Wetted Perimeter.

It is important that the river has sufficient space also taking into account future climate changes.

In the Netherlands, since 2006, the government is implementing the programme “room for river”

to provide the river sufficient space in order to address flood management (taking into account

climate change), landscaping and the improvement of environmental conditions.

Providing sufficient space, especially in dynamic rivers such as in Nepal, is crucial for a long term

development of the river basin. Lacey’s wetted perimeter, as applied in Nepal, is an empirical

formula often used to defined the required width of alluvial rivers mainly for irrigation structures

and bridges. The defined width is based on the concept to avoid silting and scouring, which is

mainly related to normal conditions, the bankfull discharge. Bankfull discharge is determined by

the discharge that a river can convey when reaching the level of the flood plain.

Figure 11: Example cross-section. (Source: Pierre Y. Jullien)

There is no clear definition of bankfull discharge. Often 1.5 and 2 years return period are used

but also mean annual floods, mean annual flows and 5 years return period floods have been used



to describe bankfull discharge in alluvial rivers. In Nepal, bankfull discharge is defined as the

discharge with a 2 year return period (DWIDM policy 2072).

Following the guideline of 3 times the Lacey’s wetted perimeter for extreme discharges such as

Q50 would result in a very wide river. An example for Mohana (PRTW.04) is given below.

At PRTW.04 the width of the river is limited, approximately 70 m. Based on the discharge (Q50),

the required width according to 3 times Lacey’s wetted perimeter is about 480 m. Taking into

account this value the embankments will be located far inland, not protecting the settlements,

infrastructures and agricultural land located between the embankments and the river, see Figure

12.

Figure 12: Example impact Lacey's wetted perimeter

Not protecting these settlements will create social unrest and the flood mitigating works will not

be accepted by the local residents.

For this location there are three options:

1. The embankments will be located inland following the value of 3 times Lacey’s wetted

perimeter. Consequence is that the houses and land between the embankments and the

river, the flood plain, are not protected. These areas are often experiencing immediate

threats from the river due to erosion and flooding. Resettlement of these people will

require additional costs;

2. The embankments will be located along the river bank, not complying with the distance

of three times the Lacey’s wetted perimeter. The people are protected but the narrow

river will have impact on the hydraulic conditions in the river. Proper erosion protection is

required for the embankments during extreme conditions. The impact of the narrow

section is included in the hydrodynamic model and appropriate measures can be taken;

3. The river bank is protected using revetments. The level of protection can coincide with a

lower return period, e.g. a return period of 1 in 2 years (bankfull discharge). The

embankments required to protect the land against a flood with a return period of 1 in 50

years will be located further inward. In this option, the settlement along the river does

receive some degree of protection for a lower return period.



It is important to provide sufficient room for the river. However, as also indicated by the PEP

experts, it is also important to take the local conditions into account. At some locations with

settlements and limited river width, a different approach is required.

Within this project, Option 2 (see above) is implemented. The people already living in these areas

are experiencing problems due to flooding and erosion and should be protected. The impact of

the narrow sections has been assessed using the hydrodynamic models and the designs have

been adapted accordingly.

4.10 Hydraulic design criteria

The hydraulic design criteria for the DED are derived from the hydrodynamic model. The results

of the hydrodynamic model used for the DED are included in Appendix A. For details about the

hydrodynamic model and different runs reference is made to the feasibility report 5 and river

hydrology assessment 6.

A steady state simulation has been adopted in the hydrodynamic model. However, the

hydrological modelling was unsteady which have accounted for some of the attenuation within

the catchment due to the floodplain storage. Therefore, the derived flows which have then been

used in the steady state hydraulic modelling account for some of the floodplain storage. The

hydrological modelling has been carried out on a reach-by-reach basis, and therefore over

individual reaches, the hydrodynamic modelling is likely to be conservative although this will not

be cumulative across the whole model. The steady state simulation of the hydrodynamic model

in this instance is not unduly conservative.

During the July 2019 ADB mission, discussions were held whether an unsteady state model

should be tested for a short reach for the assessment of uncertainties associated with steady

state modelling. As the river basin has been modelled for the whole reach the cumulative impact

of floodplain storage over a longer reach that would really show the impact of the difference

between steady and unsteady methods and would be different basin to basin. An unsteady test

will require an assessment of the critical storm duration for the selected reach as volume as well

as peak flow will become relevant. The storm duration used in the current steady state would

generate a lower flood level for the selected reach, however, it will not be representative of the

true risk.

The 1D modelling for the Mawa Ratuwa basin was developed using extended cross-sections

rather than explicit modelling of flow paths within the floodplain (which would require a 2D model,

for which sufficiently detailed data was not available at the time of the study) has the potential to

overestimate floodplain storage as small obstructions to the flow, such as high ground and

earthen field boundaries, are not picked up, and regions of the floodplain that are not connected

to the river at medium flows can be utilised for storage before they would become active. This

has been minimised where possible with the use of levee markers but cannot be avoided in all

situations with 1D modelling. Unsteady modelling, without appropriately detailed representation

of the floodplain has the potential to overestimate floodplain storage. Using steady state

modelling removes this uncertainty as the storage areas are already considered to be utilised.

5 Feasibility Study: Mawa – Ratuwa, Package 7: WRPPF: Preparation of Priority River Basins Flood Risk Management Project, Nepal,Mott MacDonald, 2019;

6 River Hydrology Assessment: Mawa – Ratuwa, Package 7: WRPPF: Preparation of Priority River Basins Flood Risk ManagementProject, Nepal, Mott MacDonald, 2019;



4.11 Room for river

The DED, making use of the hydrodynamic model, is a 2-step approach:

- Step 1: Run 2, which includes the impact of climate change but without designed

structures. This run provides the design criteria for the first DED;

- Step 2: Run 3, which includes the impact of climate change and the designed

structures.

It is important to check the impact of the designed structures with the hydrodynamic model. This

in order to assess the impact of the structures (difference between Run 2 and 3). It is important

that the due to the proposed structures, the water levels do not increase significantly. A high

increase in water levels would mean that the river is too constricted. In addition, the change in

water level needs to be restricted to avoid increasing the risk to adjacent flood plain areas should

the defences fail. It should be noted that there are no rules of thumb to be applied; within this

project a maximum rise of water levels of 30 cm has been accepted.

4.12 Survey works

Topographical surveys have been conducted in 2018 within the project Package 7: WRPPF:

Preparation of Priority River Basins Flood Risk Management Project. Based on the surveys the

hydrodynamic models and designs were prepared. The topographical surveys have been

submitted to the WRPPF (January 2019). Reference is made to the final reports:

- Deliverables – Final Social Survey Report for Detailed Design Project (July

2018);

- Detailed Design Projects (Mawa – Ratuwa) Additional Survey (December 2018).

In summary, the topographical survey created cross-sections of the river and 100m of the banks

at minimum 250m intervals down the river at the structure locations. Supplementary levels were

taken to form the L-profile of the river banks. Standard static DGPS Survey method was adopted

for the benchmarks, with total station used for the levels.

In general, topographical surveys in Nepal use the WGS 84 datum. Since the seven parameters

to convert ellipsoidal height to Orthometric height has not been defined for Nepal it is standard

practice in Nepal to use the ellipsoidal height in order to obtain better results.

Refer to Topographical Survey Report, December 2018 for locations and co-ordinates of the

bench marks used for this works package. The nearest IGS station used for the survey was Lhasa,

China (Longitude 910 06’ 14.510073”E, Latitude 290 39’ 26.40090”N, Ellipsoidal Height

3624.612m). The vertical datum across all sub-projects are the same which was carried out with

reference to the coordinates that was marked using the DGPS (in WGS 84 datum).

All drawings are based on WGS 84 North 44R coordinate system.



5 Detailed design of civil works

5.1 Introduction

The flood mitigation structures to be considered for the DED are embankments, gabion

revetments, spurs, launching aprons and outlet structures. The design of these structures is

provided in Sections 5.2 to 5.7, the use of nature-based structures is addressed in Section 5.8

and the results of the DED are summarised in Section 5.9.

Standards and Guidelines are discussed in section 4.3. Appendix B.1 documents in detail theStandards and Guidelines that were used for the various aspects of the design.

5.2 Embankment Design

5.2.1 General description

Embankments are earthen structures constructed along the river to prevent water from entering

adjacent areas that would otherwise cause damage to crops, settlements, and threaten human

life and livestock.

As outlined in section 3, the locations of the embankments were suggested in pre-feasibility, then

verified following hydraulic modelling and site visits undertaken during the feasibility study. The

crest level of the embankments is defined based on the High Flood Level from the hydraulic

modelling plus freeboard (see section 4.8). The highest embankment proposed in the two detailed

design basins is 5.95 m on the countryside and 7.25m on the riverside (note this embankment is

in Mohana Khutiya; PRTW04. In addition, it should be noted that this embankment was removed

from the loan work package due to proximity with the Indian border). Note that if there is a

localised low area of land; this area of ground should be levelled out to avoid embankments higher

than 5.95m.

As common practise in Nepal, the crest width of the embankments will be 5 m. This provides the

opportunity to access the embankments for inspection and when required maintenance works.

For that reason, the crests consist of a strip of 0.5 m of grass along each side of a 4 m width of

compacted gravel. A ramp of 1 in 10 slope has been provided where the proposed embankment

ties with an existing access track.

Side slopes of 1 in 2 are proposed in "Guidelines for Preparation of DPR for Flood Management

Works, Government of India, Central Water Commission"; slope stability analysis was undertaken

to confirm whether this is safe slope to use, as discussed in the following sections.

The countryside slope will be grassed to project against erosion caused by rainfall. This is crucial

as instability of the inner slope could result in failure of the entire embankment. It is proposed to

plant Vetiver grass (known locally as Khas or Kas grass) in a grid system; species that are

particularly beneficial in this context have dense but short root systems that will sit within the

sweet soil layer. Between the Vetiver planting, grass seeding has been specified to ensure a

consistent grass cover.

Gabion revetments have been proposed to protect the riverside slope, the design of which is

discussed in Section 5.3.

A typical cross-section of a protected embankment is shown in Figure 13.



Figure 13: Typical cross-section embankment with revetment

5.2.2 Material parameters

The embankment material will be sourced locally from the available river bed material. Due to a

lack of existing geotechnical data in the region and geotechnical investigations not been

undertaken at this phase of the project, soil parameters were originally assumed based values

from the DPR. The DPR is a document prepared by the People’s Embankments Programme

(PEP) field office and includes the required river training works for the whole river basin located

in the Terai area, from the foothills to the border with India. The DPR gives the following details

for the reaches:

Mawa - Ratuwa:

- In the upper reaches near foot hills, round boulders and gravels are predominant bed

material

- In lower reaches sand and silt are main bed materials. Downstream of the bridge bed

materials observed are sand, silt and alluvial soil.

The soil used for the embankment fill varies dependant on the basin in which the embankment is

located, with coarser soil in the upstream part of the reach and finer soil downstream. In absence

of site-specific ground investigation data, two cases are assumed; Sandy Gravel with Fines and

Silty Sand.

Geotechnical investigations to include intrusive investigations, in-situ and laboratory testing, have

been specified by the consultant team and included within the bidding documents. The purpose

of these investigations is to confirm the design assumptions prior to the start of construction.

The DPR contains soil parameters for the assumed soil types; these were revised using

alternative international standards following a review process. For cohesion, the DPR states for

perfectly saturated cohesive soils the cohesion value is about 200 kN/m2 and for perfectly

cohesionless soil it is zero. Therefore, for the embankment design the cohesion of soil is taken

as 2.5% of that of a perfectly saturated cohesive soil. Hence, the cohesion for the Sandy Gravel

is taken as 5 kN/m2. However, international best practice assumes a cohesion of 0 kN/m2. The

Friction angles and unit weights suggested in the DPR were re-assessed using the relationships

set out in British Standards BS 8002:1994 and 8004:1986; the calculation for the friction angles

is contained in Appendix B. Permeability was selected on engineering judgement.

The resulting geotechnical parameters to be used in the design of the permanent are shown in

Table 5.



Table 5: Soil parameters adopted for the design

Soil Type Friction Angle(degrees)

Cohesion(kN/m2)

In-situ Unit weight(kN/m3)

Permeability(m/sec)

Sandy gravel containing fines 36 0 21 1 x 10-3

Silty sand 33 0 19 1 x 10-5

Foundation material 30 0 20 1 x 10-6

These material parameters and the resulting design of the embankments must be verified by the

Engineer based on the findings of the specified investigations prior to the commencement of

construction.

5.2.3 Slope stability

The slope stability analysis for the maximum height embankment was carried out using the

software package GeoStudio Limited. This numerical analysis software includes limit equilibrium

stability analysis and seven finite element applications for modelling geotechnical and earth

science problems. For slope stability analysis, the limit equilibrium (Bishop) Method is used.

The following sections outline this analysis.

Empirical methods have also been used to confirm the stability against sliding.

5.2.4 Design loads

The following Design Loads were taken into account during the analysis.

Dead Loads

The dead load of the embankments is taken from the Unit Weights of soils as outlined in Table 5.

The gabion protection was not considered in the analysis.

External Loads

External loads are loads imposed on the ground/structure by structures, surcharges, anchorages

and other sources. A case was tested (case A1; see Table 8) with surcharge from a large car on

the access track was applied as 2no point loads of 10kN, and an allowance for 200mm overbuild

applied as a uniform distributed load on the crest (assuming soil weight of 21kN/m3).

Water Loads

Loads due to the weight or pressure of water (as distinct from the effects of pore water pressure

on material strength through the principle of effective stress). A case considering the High Flood

Level (as ascertained through the hydraulic modelling) has been analysed.

Earthquake Loads

The Operating Basis Earthquake (OBE) has been considered in the analysis. The performance

criteria related to this event is that there should be no loss of serviceability and the dis placements

should be minimum for the OBE event.

International best practice allows for both the pseudo-static and displacement

approaches. SP117A from the California Geological Survey use the pseudo-static analysis as a

conservative screening analysis and the recommended value of seismic coefficient is based on a

displacement level. It was chosen to adopt a pseudo-static approach.



The design peak ground accelerations (PGA) were estimated for the OBE case. The following

steps were undertaken;

● Assess Material Vulnerability of the embankment (liquefaction, flow failure etc)

● Determine Seismic Zone Factor from Local Seismic code (Nepalese Seismic Code; Nepal

National Building Code, NBC 105 Seismic Design of Buildings in Nepal)

● Determine Pseudo Static Coefficient relating it to Peak Ground Acceleration (PGA)

● Determine Performance Criteria for (OBE level)

● Determine acceptable settlements and Factor of Safety (FOS) in seismic conditions

● Assess performance of embankment in seismic conditions using a pseudo-static approach

The choice of coefficients used in the slope stability analysis is subjective. A number of codes

and publications refer to a horizontal seismic coefficient for slope design, a fraction of the design

PGA, for which, provided the slope can be demonstrated to be stable, a reasonable level of safety

is provided. I.e. any resulting deformation due to the earthquake is negligible. The seismic hazard

coefficients based on Nepalese code provide a zone factor of 0.90 to 0.96. The code does not

relate these zonal factors to the return period of earthquakes. It is anticipated that these relate to

the MCE (Maximum Credible Earthquake). Usually in the Indian seismic code the OBE level is

taken as half of the MCE level.

Based on the seismic zoning map from the Nepal Seismic Code, this factor can then be scaled

by a zoning factor. Following this, the pseudo static coefficient was obtained by multiplying by 0.5

(various sources recommend different values; Eurocode 8 and Hynes-Griffin Franklin 1984

recommend 0.5). This gives the resulting coefficient for OBE as outlined in Table 6.

Table 6: Proposed Seismic Parameters for Design

Basin Nearest DistrictZone factor forMCE

Zone Factor forOBE

Pseudo StaticCoefficient forDesign for OBE

Mohana Khutiya Dhanagadi 0.90 0.5 * 0.90 = 0.45 0.5*0.45 =0.225g

Mawa Ratuwa Damak 0.96 0.5 * 0.96 = 0.48 0.5*0.48 =0.24g

During a pseudo static analysis, the horizontal pseudo-static force has a larger influence on the

FOS than the vertical pseudo-static force, as Fh reduces the resisting force and increases the

driving force. Thus, the analysis is done for the horizontal pseudo static forces only.

Other seismic hazards like liquefaction should also be considered for the foundation material.

Other

Major geological loads, for example large horizontal loads from stresses locked up in the

geological strata are not anticipated.

An end of construction case was considered which would analyse the embankment fill as

undrained, however as the materials are free draining this was not undertaken.

5.2.5 Seepage

In the original design analysis, the egress point of the phreatic surface was estimated by assuming

that the line follows the basic parabola except at ingress and egress point of seepage which has

been corrected as suggested by A. Cassagrande. These calculations are show that the phreatic



surface for the design water level exiting the embankment above the toe level for the design water

level, however it is noted that this water level occurs only for very short periods of time.

Seepage was investigated further using the GeoStudio SEEP/W software. The following should

be noted;

● Saturated/unsaturated model was selected

● Steady state seepage assumed based on the HFL

● Estimated volume water content function using a saturated water content of 0.3

● Hydraulic conductivity for the embankment fill as per Table 5. Sensitivity was done with lower

permeabilities for the embankment fill, finding little difference in the seepage profile

● Assumed no anisotropy i.e. same hydraulic conductivity in all directions (ky/kx ratio is 1)

● Activation Pore Water Pressure as 0

● The foundation is included in the analysis; defined as saturated

The outputs of the seepage analysis were linked within the model to the cases using the maximum

water level case.

Rapid drawdown cases were also analysed; firstly, the simple effective method was undertaken,

which is notably conservative as it assumes an instantaneous drawdown. Following this, two

additional drawdown cases of 2 days and 6 days/1m per day were analysed.

It should be noted that in all cases it was assumed that the time at which the HFL occurs is

sufficient to fully develop the steady state seepage condition (i.e. worst case analysis).

5.2.6 Factor of safety (FOS) and design cases

In order to assess the geotechnical safety of the proposed embankments against different

geotechnical failure mechanisms, analyses consider a minimum required factor of safety which

must be met. This factor of safety represents the ratio between the driving forces that may

otherwise lead to failure and the resisting forces which provide resistance to prevent failure from

occurring.

Factor of Safety = resisting forces / driving forces

Various standards and guidance documents have different recommended Factors of Safety for

different load cases. A Factor of Safety of 1.5 for normal loading conditions is commonplace.

It was decided to use United States Army Corps of Engineers (USACE) Manual EM 1110-2-1902 (2003) to guide the design cases and required Factors of Safety. These manuals arecommonly used in international practice. In accordance with standard procedures forembankment stability assessments, the factor of safety of potential failure surfaces isassessed for various load cases as outlined in

Table 7. The load cases are categorised into Usual, Unusual and Extreme according to their

probability of occurrence and duration. The embankments are generally set back from the thalweg

(lowest incised channel) and would not be impounded in the dry season. For the purposes of this

analysis Normal Water Level is considered to be just at the base of the riverside slope.



Table 7: Summary of Cases Analysed and Acceptable FOS

Ref Load Case Targetminimum FOS

Surcharge WaterLevel

Facesanalysed

Loadtype

1 Normal Water Level withsurcharge

1.3 -1.4 Yes NWL Riverside &Landside

Unusual

2 Rapid drawdown;instantaneous

1.2 No HFL toNWL

Riverside Unusual

3 Max Water Level; steadystate seepage

1.3 -1.4 No HFL Riverside &Landside

Unusual

4 Earthquake (OBE) 0.95 - 1.1 No NWL Riverside &Landside

Extreme

Various models were set up to test different embankment arrangements, including:

● Model A) Sandy Gravel; Maximum Embankment height of 6m; 1 in 2 slopes

● Model B) Silty Sand; Maximum Embankment height of 6m; 1 in 2 slopes

● Model C) Sandy Gravel; Embankment height of 2m; 1 in 2 slopes

● Model D) Sandy Gravel; Embankment height of 6m; 1 in 3 slopes

● Model E) Sandy Gravel; Embankment height of 6m; 1 in 2 slopes; rockfill drainage area

added

● Model F) Sandy Gravel; Embankment height of 6m; 1 in 2 slopes; berm added

● Model G) Silty Sand; Maximum Embankment height of 6m; 1 in 2 slopes; rockfill drainage area

added

Models A and B were run initially, finding that the FOS were not acceptable. This required the

need for additional runs (Models C to G).

5.2.7 Results

Key points from the analysis of the various Models and Cases are as follows;

● Based on the adopted soil parameters, the maximum height embankment (6m) is not stable

at 1 in 2 slopes with FOS at Maximum Water Level for Sandy Gravel and Silty Sand below 1.

● For the cases above, seepage is shown to be exiting just above the toe. It is assumed that this

is causing the localised slope stability issues based on the location of the critical slip circles

● Smaller heights of 5m and 4m were initially trialled which were also unfavourable. Case C3

shows that a 2m height embankment (with a riverside slope height of 2.6m) is shown to have

a reasonable FOS of 1.3

● Models D, E and F were then undertaken to analyse options for the maximum height

embankment which would make the slopes stable;

– Firstly, in Model D, existing slopes were flattened to 1 in 3. For Case D3 (Sandy gravel,

Maximum Water Level), the FOS improved to 1.3

– Model E retains the existing 1 in 2 slopes but incorporates a 2m high rockfill drainage area

at the landside toe with higher permeability than the main embankment fill (see Figure 14).

For Case E3 (Sandy gravel, Maximum Water Level), this improved the FOS to 1.3

– Finally, Model F retains the existing 1 in 2 slopes but incorporates a berm at the landside

toe, comprised of the same embankment fill. For the maximum water level case, although

the lowest FOS was 1.05, the slip circles associated with unacceptable FOS were all within



the berm as opposed to the main body of embankment. The slip circle affecting the

embankment with the lowest FOS was 1.3

● Based on the instantaneous drawdown, the FOS were generally not acceptable. For the final

design cases, more onerous analysis was undertaken as outlined in the following section

● The slopes are not stable in the earthquake case. This is discussed further in section 5.2.9.

5.2.8 Final design

During the July 2019 ADB mission, tripartite meetings with the consultant, DWRI and ADB

concluded that the 1 in 2 slopes with rockfill drainage area option as shown in Figure 14 was most

favourable. This was mainly due to retaining the original footprint of the embankment.

Figure 14: Set up of Model E and SEEP/W results

The Models and Cases were then finalised for these final designs. The resultant FOS for the final

designs is shown in Table 8.

Table 8: Results of slope stability analysis for Final design

Ref Load Case Target minimumFOS

CountrysideFOS

RiversideFOS

E) Sandy Gravel; Maximum Embankment height of 6m; 1 in 2 slopes; 2m rockfill drain

E1 Normal Water Level with surcharge 1.3 - 1.4 1.5 1.3

E2 Rapid drawdown (2-day) 1.2 N/A 1.1

E3 Max Water Level 1.3 - 1.4 1.3 1.2

E4 Earthquake 0.95 - 1.1 N/A 0.7

G) Silty Sand; Maximum Embankment height of 6m; 1 in 2 slopes; 2m rockfill drain

G1 Normal Water Level with surcharge 1.3 - 1.4 1.3 1.3

G2 Rapid drawdown (2-day) 1.2 N/A 1.1

G3 Max Water Level 1.3 - 1.4 1.3 1.2

G4 Earthquake 0.95 - 1.1 N/A 0.7



The slope stability slip circle diagrams showing the FOS are contained in Appendix B.2.2. In

regards to each case;

● The slope stability is acceptable in the Normal Water Level with surcharge case.

● The 2-day and 6-day rapid drawdown cases were analysed for the riverside slope. For the

Sandy Gravel case, although the FOS was below 1.2 at certain time steps, these slip circles

were for localised shallow slips. The gabion protection on the riverside slope in these areas

will help stabilise the slope. Therefore, it was deemed acceptable. Following flood events, the

embankment and revetment should be inspected for any damage from shallow slips, with

repairs undertaken and grasscover restored. For the Silty Sand case, the FOS between 1.1

and 1.2 were deeper slip circles. It is still anticipated that the gabion protection will aid this

somewhat, however the FOS may be less than the target of 1.2. Embankments must be

inspected following flood events and any required repairs made immediately.

● The maximum water level case FOS is 1.3 for the countryside slope. For the riverside slope,

the lowest FOS is 1.2, however this is associated with a shallow slip circle at the toe; 3 other

slip circles in this location have a FOS of 1.2. The gabion protection on the riverside slope in

these areas will help stabilise the slope. Therefore, it was deemed acceptable as the FOS for

all other slip circles was 1.3 or above.

5.2.9 Stability under seismic loading

The embankments are not stable in the earthquake case with the proposed seismic coefficients

shown in Table 6. Additional analysis was undertaken on the riverside faces of Cases A and E to

find what horizontal coefficients could be applied to get a FOS of 1 to evaluate the yield

acceleration for the slope. This analysis showed that

– Model A (slope 1 in 2) horizontal coefficient of 0.10 gives a FOS of 1.0

– Model E (slope 1 in 2) horizontal coefficient of 0.10 gives a FOS of 1.0

This suggests that the yield acceleration (0.1g) is lower than the pseudo static acceleration

coefficient applied on the slope (0.225g). Slope will have some residual displacements following

the design earthquake. Usually there are detailed methods available to evaluate this displacement

but simplified empirical methods have been followed here to give an expected range of

movements for the slope. The empirical method that has been used for slope displacement

analysis has been published in peer reviewed journal and is recommended by Rathje &

Antonakos (2011). This method is designed to facilitate conducting sliding-block analysis (also

called permanent-deformation analysis) of slopes in order to estimate slope behavior during

earthquakes.

Broadly this is based on the following steps

● computation of the max seismic coefficient (kmax = 0.225g) for the potential sliding mass of the

slope and comparing it with the corresponding yield acceleration (ky= 0.1g). The yield

acceleration is the value of acceleration for which the Factor of Safety is 1;

● this method consists of accounting for the dynamic response of the sliding mass. This

framework includes predicting the seismic loading for the sliding mass in terms of the

maximum seismic coefficient (kmax) and the maximum velocity of the seismic coefficient-time

history (k–velmax);

● the predictive models are a function of the peak ground acceleration (PGA), peak ground

velocity (PGV), the natural period of the sliding mass (Ts), and the mean period of the

earthquake motion (Tm); and



● the empirical predictive models for sliding displacement utilize kmax and k–velmax in lieu PGA

and PGV, and include a term related to the natural period of the sliding mass. This unified

framework provides a consistent approach for predicting the sliding displacement of rigid and

flexible slopes.

The following parameters are used for the assessment. This is a sample calculation

● Friction angle =33 degrees

● Representative SPT Value =22

● Shear wave velocity of the soil =200m/s

● Mean period of soil column = 0.12s

● Degraded period of soil column =0.18s

● Yield acceleration =0.1g

● Maximum acceleration for OBE (without site effects) = 0.45g

● Ratio of yield acceleration/ Maximum acceleration = 0.22

● Mean period of earthquake ground motion =0.64s

● Magnitude of earthquake for OBE =6.0

Based on broadly assumed parameters which are consistent with the slope we would expect a

deformation of 15 to 20cm for the unrestrained slope. This would mean that some repair work

would be needed following an earthquake which should be specified in the maintenance manual.

5.2.10 Liquefaction of the foundation soil

Liquefaction is a process by which non-cohesive or granular sediments below the water table

temporarily loose, totally or to a significant degree, their strength when subjected to strong ground

shaking during an earthquake. Typically, saturated, poorly graded, loose, granular deposits are

most susceptible to liquefaction.

The potential consequences of liquefaction include:

● slope instability (e.g. flow failures and lateral spreading);

● loss or reduction of bearing capacity;

● excessive settlement;

● increased lateral pressure on retaining walls;

● floatation of buried structures.

Eurocode 8 Part 5 Clause 4.1.4 states that the liquefaction hazard may be neglected when the

ground surface acceleration (αS) is less than 0.15g and at least one of the following conditions is

fulfilled:

● the sands have a clay content greater than 20% with plasticity index > 10;

● the sands have a silt content greater than 35% and, at the same time, the SPT blowcount

value normalised for overburden effects and for the energy ratio N1(60) > 20;

● the sands are clean, with the SPT blowcount value normalised for overburden effects and for

the energy ratio N1(60) > 30.

For the current scenario, the friction angle for the founding soil is 30⁰ and the equivalent SPT is

less than 15. The water table will be high due to proximity with the river and the peak ground

acceleration at the site could be between 0.4 to 0.3g. Thus, liquefaction is a likely scenario and

should be verified by detailed site investigation.



Thus, it is recommended that a liquefaction assessment is performed when detailed ground

investigation information is available. In order to improve the resistance against liquefaction the

foundation for the embankment will require further widening of the foundation which will lead to

more land acquisitions and embankment fill materials (and the cost of compaction). Other

potential measures could include dynamic in-situ compaction, excavation of soils and

recompacting in layers or techniques such as soil cement mixing. It will likely not be economically

viable to design and construct an embankment which can fully resist possible liquefaction

damage. It is assumed that any damage to the embankment due to earthquake will be repaired.

The joint probability of extreme flood events and earthquake is relatively low and therefore it is

expected that the flood embankment shall be inspected after major earthquake events and any

damage and/or displacement of materials shall be repaired immediately to avoid further risk of

breaching and embankment failure. However, the design has been improved by adding geotextile

wrapping under gabion mattress and embankment rockfill material which will assist in keeping

embankment material integrity during earthquakes to some extent.

5.2.11 Rockfill drainage area

Based on 6m high embankment requiring a 2m high drain area, for the other embankments rockfill

drains were specified at 1/3 the embankment height. Embankments less than 2m were shown to

be stable from the slope stability analysis without the drainage area.

The drainage area heights were generalised for ease of construction, as follows;

Embankment height <2m 2-3m 3-4m 5-6m >6m

Drain height None 1m 1.33m 1.67m 2m

The side slope for the drainage area is 1 in 1, and it will be wrapped in geotextile to reduce

migration of fines from the embankment fill. It is proposed to cap the drain on the exposed

countryside face with the same sweet soil layer as on the main embankment, in order to prevent

damage to this layer by rocks being removed.

5.2.12 Bearing capacity

Assuming a unit weight of 21 kN/m3 for the gravel fill embankment as the worst case, the weight

of a 4m embankment is 52 kN/m2 and therefore the requirement for the bearing capacity of the

foundation soil needs to be specified as a requirement within the bidding documents. This bearing

capacity should be achievable for most loose sands and soft clays according to British Standard

8004: 1986.



Figure 15: Typical bearing capacity values for different soil types

Source: Table 8.1 from BS 8004: 1986

5.2.13 Construction

Ground Investigation (GI) will be included in the construction work packages and the Contractor

will be required to verify the design when specific properties will be available after the GI

The embankment material should be well compacted at maximum 300mm layers during

construction and this requirement has been included in the technical specifications. When tie-ing

in to existing embankments, the end of the existing embankments will firstly be benched at

equivalent 300mm layers. Then the compaction of the new embankment layers will occur at these

same layers, ensuring a robust connection.

If the proposed Sandy Gravel or Silty Sand cannot be sourced locally from the river bed the factor

of safety will be reduced. The findings of the geotechnical investigations mentioned above shall

be reviewed by the Engineer prior to the commencement of construction and any localised

changes to the design, based on the locally available materials, shall be confirmed at this stage.

A settlement allowance of 2% of the embankment height or 200 mm is proposed whichever is the

higher. The Contractor shall provide an allowance for settlement above the design crest level

during construction.

5.2.14 Tie-ins

At their upstream and downstream ends, the various embankments tie in to different existing

features, namely;

- Existing embankments

- Natural ground

- Existing bridge foundations

- Existing access track

In certain locations, the level of these features is lower than the proposed embankments. If the

proposed embankments are outflanked, this could cause flooding of intended protected land, and

cause increased risk of embankment damage or breach. In order to reduce this risk, a cost

allowance for extended tie-ins has been included. Precise locations of tie-ins should be confirmed

on site during construction, but at the least should direct flow from the protected land into the main



channel, and tie into features with level equal to the proposed crest level where possible, HFL as

minimum.

In the case of existing embankments, it is recommended that a review of the existing

embankments is undertaken as an additional work, including crest level, 1 in 50 year flood level

and a detailed condition assessment. The result of this would be a project to raise existing

embankments to ensure they meet the same level of protection (1 in 50 year). In the interim, a

generalised cost allowance for raising the existing embankment in the vicinity of the tie-in has

been included.

5.2.15 Repair to existing embankments

Detailed condition assessments were not undertaken as part of this TA project. The Department

has in July 2019 provided a note specifying repair works required to existing, costs of which have

been estimated and included in the BoQ. In addition, based on findings from site visits, the

following is noted;

- Grasscover on existing embankments may be limited. The Department should re-seedwhere possible

- Erosion issues such as raincuts may be present in the existing embankments whichshould be repaired.

- Material specification/grading of the existing embankments is unknown; although thematerial used to construct is also dredge sourced from the river, the existing ones mayhave large cobbles mixed in which have been screened out for this design. Thereforeslope stability/seepage characteristics may differ

To ensure the integrity of the new embankments and avoid a breach, it is recommended that theDepartment undertake a detail condition assessment of all existing embankments andundertake the required repair, improvement and raising works.

5.3 Revetments


Depending on the flow velocities, embankments need to be protected against erosion.

Revetments protect the embankments against erosion. The revetments need to be sustainable

structures that are environmentally friendly and are low-costs solutions. Protection can be done

by using hard revetment such as gabions or nature-based solutions such as grass. In the Terai

often gabion revetments are used, see Figure 16.

Figure 16: Gabion revetments in Mawa - Ratuwa Basin



Gabions are suitable because:

- Boulders to fill the gabions are locally available, which will reduce the costs compared

to concrete / reinforced concrete;

- Gabion structures are commonly applied in the Mawa – Ratuwa basin and are familiar

to those who maintain the structures. Using similar structures will benefit the

maintenance works as all structures require the same type of maintenance;

- Gabions, compared to e.g. concrete structures, are flexible and adaptable structures

that 1) can cope with uneven settlements; and 2) can easily be adjusted (e.g. adding

another layer of gabions) in case of changing river characteristics.

The cages of the gabions will be machine made using double twisted hexagonal woven heavily

coated steel wire. Geotextiles will be used as filter layer under the gabions to reduce the

migrations of fines from the embankment fill.

Further details of the gabions and geotextile is outlined in the Specification document produced

for the works.

It is possible to protect the entire slope from bed level up to the crest level using gabions. One of

the reasons for doing so would be that water levels could exceed the design water level. However,

for the environmentally friendly character of the structures and to integrate them in the

surrounding landscape, it was chosen to use grass for the area above the design water level.

5.3.2 Design

The design of gabion revetments was undertaken following the methodology in Handbook for

Flood Projection, Anti Erosion and River Training Works, Government of India Central Water

Commission (2012).

The design is outlined in Appendix B.3.

In summary, the weight of gabion unit and thickness of mattress is calculated based on maximum

channel velocity from the HECRAS model for the relevant revetment section. It was chosen to

use these maximum velocities instead of the channel average velocities in order for the design to

be conservative, and to take into account higher velocities that will occur at the outer bends. The

HECRAS model is able to ascertain the difference in velocities along the cross-section, hence the

increased velocity at the bends at the model cross-sections were able to be analysed. It should

be noted that the left and right bank flood plain velocities from the HECRAS model were looked

at, however these were lower than the maximum main channel velocities so were not used.

The thickness of mattress calculated was then rounded up to the nearest standard gabion

mattress thickness, 0.3m or 0.5m.

It is important to ensure the grading of stone sizes is appropriate to ensure that the stones do not

move excessively within the gabion during high flows, causing increased wear. For the grading,

an additional calculation was been undertaken following the CIRIA Manual on scour at bridges

and other hydraulic structures, second edition (2015). This follows the Escarmeia and May (1992)

method for gabion mattresses.



5.4 Spurs


Spurs have the function to divert the flow in order to protect the embankments. Sedimentation is

expected between the spurs, due to the low flow velocity. Spurs should not be applied at those

locations where diverting the flow would potentially affect settlements directly at the opposite

bank. Spurs are mainly proposed in outer bends where the flow directly attacks the banks and

causes erosion. Diverting the flows will protect the banks and stimulate sedimentation.

The spurs can be constructed using gabions. A typical cross-section is shown in Figure 17.

Figure 17: Typical cross-section spur

5.4.2 Design

The design of spurs was undertaken following the methodology in Handbook for Flood Projection,

Anti Erosion and River Training Works, Government of India Central Water Commission (2012).


In summary;

● The spurs have been designed based on the water level depth. The spurs will be a combination

of submerged and unsubmerged, with a maximum height of 3m from the river bed based on

engineering judgement and standard practice in Nepal

● They are positioned at 90˚ to the banks

● The location of the spurs has been chosen on the outer bank of bends where velocities are

high (outer bends have been avoided where deposition was found to be notable on the outer

bend). In addition, in some straighter reaches spurs were designed based on engineering

judgement on the site visit, where notable bank erosion was occurring.

● The length of spurs is calculated by 2.5 multiplied by the calculated maximum depth of scour.

It is ensured that the length of spurs is not greater than 1/5th of the width of flow

● The spacing of the spurs is 2.5 multiplied by the calculated length of spur



5.5 Launching aprons


The areas with the identified priority works experience erosion threatening existing settlements,

agricultural land and infrastructure. At some locations, as can be seen from the hydrodynamic

modelling, velocities can increase. Embankments need to be constructed to protect the adjacent

areas during flood events. To maintain the stability of the structures (spur, revetment and

embankment) it is important to ensure that scouring will not cause failure (instability) of the

structure. To protect the structures from scour, launching aprons are constructed. Launching

aprons protect the toe of the structures (e.g. spurs and revetments) against erosion, maintaining

the stability of the entire structure. In Nepal, rectangular and semi-circular launching aprons are

implemented, see Figure 18.

Figure 18: Types of launching aprons

For the DED rectangular launching aprons are applied, which are easier to construct and to

maintain.

Launching aprons have been specified at all locations of proposed embankment, revetment or

spur.

5.5.2 Design

The design of gabion revetments was undertaken following the methodology in Handbook for

Flood Projection, Anti Erosion and River Training Works, Government of India Central Water

Commission (2012).


In summary, the dimensions of the launching apron are based on calculations for scour depth.

The calculations are based on flowrate which is ascertained from the flood model for the various

locations.

5.6 Toe drain


A toe drain has been specified at the countryside toe to ensure that seepage and direct rainfall

onto the embankment is collected and transferred away. This will reduce the risk of standing water

occurring at the toe which can impact slope stability.

It is proposed to use an open channel drain along the toe. A perforated pipe option was discussed

but the maintenance requirements if the pipe becomes blocked are more onerous than clearing

an open channel.



5.6.2 Design

The toe drain has been sized based on expected rainfall directly on the embankment slope in the

1 in 10 year rainfall event for a 1km stretch of embankment. The trapezoidal channel was sized

based on Mannings equation for open channel flow. Refer to Appendix B.5 for more information.

The slopes of the drain vary; 1 in 500 was used for the hydraulic design but slopes may be

adjusted locally to avoid deep excavation of the existing ground at the proposed embankment

toe.

Outlet structures have been proposed to convey these flows to the river. Refer to the following

section 5.7 for their arrangement and design.

5.7 Outlet structures


At several locations there are clear locations (such as streams or drainage ditches) where the

embankments block the discharge of excess rain water towards the river. At those locations, outlet

structures are constructed. An example of such an outlet structure is indicated in Figure 19. The

outlet structures are equipped with an automatic flap gate preventing river water to flood the

adjacent land. During low water levels, excess rain water can be drained to the river.

Figure 19: Example outlet structure

In addition, outlet structures are proposed to convey toe drain flows.

The outlet is equipped with trash racks to avoid trash influencing the proper operation of the flood

gate. An additional, manual operational gate is provided that can be closed for emergency or

maintenance purposes.

5.7.2 Design

The design of the culverts is based on an assumed catchment area from aerial imagery and

mapping, and the 1 in 10 year rainfall event. The design of the culverts is contained in Appendix

B.4; as outlined the 1 in 50 year event is also considered however the high flood level during this

event would prevent gravity flows, hence the culverts would be overdesigned.

The design of the culverts for the toe drain flows are contained in Appendix B.5.

5.8 Nature-based solutions

The Consultant has considered implementing natural-based solutions at all locations. Whether a

nature-based solution has been proposed depends on the characteristics of each site;



- Grasses are used to protect embankments; a) the outer (river-side) slope of the

embankment above the design water level; b) the crest of the embankment; and c) the

inner (land-side) slope. Further, as mentioned above certain grasses may also be

incorporated into the revetment gabion baskets. Some embankments which are setback

from the riverbank and are not exposed to high velocities or wave attack may not need

gabion protection below the design water level and may be simply protected by grasses;

- Integrate Vetiver grass into hard structures in a rural landscape. Vetiver grass will be

planted into the top rows of revetment gabions as a pilot project. The Vetiver grass can

grow within the gabions making it a stronger structure and more environmentally friendly;

- Bamboo porcupines have been considered on a case-by-case basis as a means of

protecting river banks from erosion and encouraging sedimentation. It is emphasized that

these types of structure do not have the same design life as hard structures and are

mainly seen as emergency or temporary works;

- Induced meander cut-offs have been considered on a case-by-case basis to straighten

the river and avoid the continued river bank erosion which is part of the natural meander

evolution process. Meander cut-offs connect the two closest parts of the meander to form

a new channel. The steeper drop in gradient will cause the river flow gradually to abandon

the old meander which will silt up with sediment from deposition. Cut-offs are a natural

based solution since they are a natural part of the evolution of a meandering river,

however they are not a permanent riverbank erosion protection solution and need to be

monitored after every flood season;

- Allowing continued erosion and regular monitoring. In certain locations it may be

advisable to allow continued erosion to occur, particularly if the adjacent erosion-risk land

has low value or low productivity. Erosion is a natural process. In these cases the erosion

situation needs to be monitored after every flood season.

Based on meetings with the WRPPF, porcupines are not included in the DED. Porcupines are

seen as short term solutions for emergency relief instead of long term sustainable structures.

5.9 Results DED

DED have been completed for all the priority works indicated in Chapter 3. For the design

calculations reference is made to Appendix B. The BoQ and the DED drawings are shown in

Appendix C and Appendix D respectively.

The DED is an iterative process taking into account the hydrodynamic model. First calculation is

made based on the design criteria of Run 2 (including climate change and excluding proposed

structures). Second calculation is based on the results of Run 3 (including climate change and

proposed structure).

In Appendix A.3 the modelling results between Run 2 and 3 are compared. The purpose of the

comparison is to see the impact of the proposed structures on the hydraulic conditions. It is

important that the due to the proposed structures, the water levels do not increase significantly.

A high increase in water levels would mean that the river is too constricted. In addition, the change

in water level needs to be restricted to avoid increasing the risk to adjacent flood plain areas

should the defences fail. It should be noted that there are no rules of thumb to be applied; within

this project a maximum rise of water levels of 30 cm has been accepted.

Based on the comparison it can be seen that the maximum difference is an increase of 26 cm,

which only occurs in one cross-section while the other sections show less or no increase in water

level. The maximum rise is acceptable.



Two embankments that were originally proposed as part of the package, PRTW.06 LB and

PRTW.06 RB are situated at the Indian Border. The proposed structures will have an impact on

the velocity and flow depth; the modelling results indicate that the impact at the structure locations

is as follows;

PRTW.06 LB:

● 0.14 m/s increase in channel velocity

● 0.10 m increase in water depth

PRTW.06 RB:

● 0.37 m/s increase in channel velocity

● 0.12 m increase in water depth

It was agreed during the ADB Mission in July 2019 that the priority works, PRTW.06 (L/B) and

PRTW.06 (R/B) from the Mawa Ratuwa sub-project will be removed from the ADB loan Work

Package because of proximity of the Indian border.

5.10 Designer’s Hazard Elimination and Management Record

A Designer’s Hazard Elimination Record has been completed for the works, as contained in

Appendix E. This outlines the primary construction risks as identified during the design process,

as well as anticipated risks associated with maintenance and use.

The Contractor must undertake their own risk assessment for the works and develop Safe

Systems of Works. In addition, DWRI should ensure the required maintenance and repair

activities are risk assessed and undertaken in a safe manner.



6 Maintenance

6.1 Introduction

Maintenance comprises all activities to be carried out (on a periodic basis) after construction, to

ensure that a structure can fulfil its functions.

Inspection and repair play an important role in this process. Periodic inspection and maintenance

is required throughout the year. It is of utmost importance that prior to the start of the monsoon

season, the structures are in good condition and able to fulfil their function. During and after the

monsoon period inspections are required to monitor how the structures cope with the extreme

events and if actions are required to support the structure.

As nature is unpredictable, also due to ongoing climate change processes, it is crucial that the

structures remain in good condition throughout the year.

Inspection and maintenance should be executed by experts from the PEP field offices. The PEP

field offices, part of the Department of Water Resources and Irrigation (DWRI), are located nearby

the basin, have knowledge of the local situation and can easily inspect the structures. Proper

maintenance is costly and government budgets should be balanced. Maintenance, however, is

not always a high priority and this means that expenses for maintenance have to compete with

other public expenses and they should be reasoned and well-founded.

The International Levee Handbook (CIRIA Manual C731) contains extensive recommendations

on institutional changes to ensure best practice Operation and Maintenance and overall safety of

the embankments. Key discussions include;

● The importance of developing an Operation & Maintenance manual

● Challenges with changing river morphology

● Typical levee failure mechanisms and the need for emergency management procedures

should the embankments be at risk of failure

● Preventing encroachment on the embankments

It is recommended that these aspects are reviewed and implemented by DWRI in order to ensure

the safety of the structures are optimised. Local community groups should also be engaged to

discuss the importance of the maintaining the integrity of the structures, and to aid with ongoing

safeguarding of the structures. For example, they could be encouraged to report defects to DWRI

(note this should not be instead of regular inspections by DWRI experts) and protect the assets

from human interventions.

In the following sections key maintenance activities are defined.

6.2 Embankments (earth works)

Embankments consists of earth works that could be protected by a revetment and is covered by

bio engineering such as grass. The level of the embankment is important to protect the adjacent

land against flooding. Regular inspections are required to assess the condition of the

embankment. It is of utmost importance that prior to the start of the monsoon season, the

structures are in good condition and able to fulfil their function. Inspections are to be conducted

during and after the monsoon to see if the embankments are damaged.



In case of damage (erosion or settlement of the crest) repair works are required. If there are

relatively small areas that have experienced damages and settlement then repairs should be

made immediately, before any further damage can take place. For filling, compacted soil is

required that is protected by bio-engineering. If there are large areas damaged it is important to

assess the cause of failure prior to repair / replacement, which could be caused by e.g. changing

hydraulic conditions. A re-evaluation of the design criteria and dimensions may be required and

therefore a suitably qualified engineer would need to be engaged to provide advice on the

necessary rehabilitation. If holes are found, e.g. animal holes, they need to be refilled with suitable

materials such as clay.

The bio-engineering, such as grass, need to be maintained in order to properly inspect the

embankments.

Inspections must also look for seepage paths on the downstream face and toe noted by localised

wet ground.

6.3 Revetments, spurs and launching aprons (gabions)

The constructed structures such as revetment, spurs and launching aprons are made from

gabions. Gabions are wire-mesh boxes filled with stones. The wire-mesh boxes can be damaged

as shown in Figure 20, which can result in failure of the structure.

Figure 20: Damaged gabions

Gabions must therefore be checked annually and at least after every major discharge event. It is

important that prior to the start of the monsoon season, the structures or in good condition so it

can fulfil its function. Periodic inspections should be conducted to identify, but not limited to, any

areas of uniformity of filling of gabions, to see if the wire-mesh is broken and stones are displaced

or escaped, scour holes and erosion at the edge of the protected area.

If there are relatively small areas that have experienced damages and displaced stones it should

be replaced immediately, before any further damage can take place. If there are large areas

damaged it is important to assess the cause of failure prior to repair / replacement. For example,

this might come about due to changing hydraulic conditions. A re-evaluation of the design criteria

and dimensions may be required and therefore a suitably qualified engineer would need to be

engaged to provide advice on the necessary rehabilitation.

6.4 Outlet structures

Several outlets structures are constructed. The function of the outlet structure is to a) discharge

excess rain water from adjacent land into the river; and b) to prevent river water to enter the

adjacent area. To prevent river water to flow into the adjacent land, outlet structures are equipped

with automatic flap gates. It is important that the outlet structures in general and the flap gates in



particular remain operational throughout the whole year. Related to the outlet structures it is

important that:

- Steel flap gates need to be coated (to avoid corrosion) and movable items need to be

checked and maintained to make sure they are working properly;

- Trash racks needs to be cleaned to allow excess water from land to be discharged to the

river;

- Prior and during the monsoon, flap gates need to be inspected to make sure that no

debris is stuck which prevents the flap gates from closing completely. When the flap gates

cannot close, river water can flow into the adjacent areas and cause flooding.

6.5 Embankment failure

The rapid onset of flooding following embankment failure would pose a greater risk to life than the

fluvial flooding if the embankments were not constructed. This highlights the critical importance

of robust maintenance of these structures.

It should be noted that in floods exceeding the 1 in 50 year, notwithstanding the freeboard, the

embankments could overtop. Due to high velocities on the downstream face from overtopping,

the embankments are particularly vulnerable to fail in these scenarios. It is crucial that the early

warning systems ensure that people evacuate during this level of flood event due to the risk of a

flood wave from breach.

Internal erosion is another common embankment failure mechanism. As outlined in section 6.2,

seepage on the countryside face and toe must be noted for during regular inspections, and

crucially after flooding events. Seepage on the riverside face should also be inspected for, which

could arise from localised ponding on the country side face. The rockfill drainage area and toe

drain systems must be maintained to minimise this risk. In addition, if the control structures fail

open during a flood event, the country side protected areas would flood from through flows into

the area.

Information provided by DWRI7 regarding the Koshi embankment breach in 2008 gave the

following reasons for failure:

● Concentration of flow towards left bank at the breached site since last few years.

● Rise in river bed level due to sediment deposition.

● Drainage congestion due to opening of 34 gates only out of 56 gates on August 18 that

contributed to scouring of spurs.

● Lack of proper inspection, observations and regular maintenance of the spur and the prompt

engineering response to the criticality of the problem

This highlights the critical nature of ongoing asset management procedures to ensure safety

following construction. Launching aprons have been included in this design to help protect the

spurs and embankments against localised scour. Ongoing inspection of bed levels adjacent to

the structures is still required to check for localised scour that might be induced by the dynamic

nature of these rivers. For example, works upstream of the river outside the control of the

7 FLOOD FORECASTING AND EARLY WARNING SYSTEM IN KOSHI BASIN, FINAL REPORT. Government of Nepal ,EmergencyFlood Damage Rehabilitation Project Component-E Project Management Component DWIDP Capacity Building Program. 2012



Department might induce morphological changes in the river which change the expected pattern

of deposition-erosion that has been analysed in this project.



References

[1] Feasibility Study: Mawa – Ratuwa, Package 7: WRPPF: Preparation of Priority River

Basins Flood Risk Management Project, Nepal, Mott MacDonald, 2019;

[2] River Hydrology Assessment: Mawa – Ratuwa, Package 7: WRPPF: Preparation of

Priority River Basins Flood Risk Management Project, Nepal, Mott MacDonald, 2019;

[3] DWIDM Pocket Diary – 2071 (2014 / 2015), Department of Water Induced Disaster

Management;

[4] River and channels revetments - A design manual, Manuela Escarameia, 1998;

[5] Downstream Hydraulic Geometry of Alluvial Rivers, Pierre Y. Julien, 2014;

[6] Design Manual for River Training Works in Nepal, Ministry of Water Resources, Water

& Energy Commission Secretariat, June 1988;

[7] WRPPF: Preparation of Priority River Basins Flood Risk Management Project,

Topographical Survey and Social Survey Watersheds, Detailed Design Projects (2

Rivers) – Deliverable 1; Engineering and Educational Services Pvt. Ltd.; July 2018;

[8] WRPPF: Preparation of Priority River Basins Flood Risk Management Project,

Topographical Survey and Social Survey Watersheds, Detailed Design Projects (Mawa

– Ratuwa Basin) – Additional Survey Works; Engineering and Educational Services Pvt.

Ltd.; December 2018.



Appendices



A. Hydraulic design criteria

In this appendix the modelling results are presented, which are the design criteria for the DED.

The first DED is done using the criteria from Run 2. The DED is included in Run 3 and a check is

made to see if the water levels not increase too much. The comparison is provided in this

appendix. The following is included:

- Appendix 0: Hydraulic modelling results of the Future Alternative 1 (Run 2). This is the

Reference Alternative (Run 1) including the impact of climate change but without the

proposed structures for 50 year return period;

- Appendix A.2: Hydraulic modelling results of the Future Alternative 2 (Run 3): This is the

Future Alternative 1 (Run 2) including the proposed structures and the impact of climate

change for 50 year return period;

- Appendix A.3: Provides a comparison of the modelling results of the different runs for the

50 year return period.

Note that these results include the original structures in proximity to the Indian border that were

removed from the package. The modelling has been undertaken with PRTW.06 L/B and R/B,

assuming that they will be constructed by the Government in a separate package. No further

modelling has been done following the removal of these embankments.

A.1 Modelling Results – Run 2 (50 year return period)

River Structure RiverStation

Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

Ratuwa 44391 283 185.47 187.16 0.006306 3.50 87.23 86.97 0.90

(upper) 44131.3 283 182.75 184.61 0.003232 2.46 115.25 79.74 0.64

43929.8 283 181.95 183.38 0.009795 2.88 98.26 119.56 1.01

43751.0* 283 179.02 180.82 0.009173 2.78 101.68 124.33 0.98

43572.2* 283 176.10 178.26 0.009513 2.77 101.99 128.96 1.00

43393.4* 283 173.17 175.72 0.009866 2.78 101.84 132.12 1.01

43214.6* 283 170.24 173.28 0.004192 3.27 112.23 137.65 0.76

43035.9 283 167.31 170.16 0.007224 3.80 75.88 60.71 0.97

42801.8* 283 165.83 169.12 0.003668 3.19 122.97 155.28 0.72

42567.8* 283 164.36 167.29 0.007505 2.58 117.55 186.55 0.90

42216.7* 283 162.14 164.73 0.007139 2.82 110.94 149.66 0.90

42099.7 283 161.40 163.84 0.007958 3.02 98.66 108.01 0.95

42072.0* 283 161.10 163.61 0.004189 2.50 122.61 137.65 0.71

PRTW.09(b) - left

bank

42044.4 283 160.79 163.60 0.001993 2.00 148.87 128.35 0.51

41985.6 283 160.41 163.01 0.006197 3.25 99.37 120.05 0.88

41885.4 283 159.71 162.10 0.007693 3.05 98.52 117.88 0.94

41746.5 283 158.75 161.10 0.005872 2.82 120.70 200.78 0.83

41617 283 157.55 160.39 0.003472 2.60 158.45 332.74 0.67

41509.5 283 157.34 159.79 0.004711 2.64 119.56 327.20 0.76

41410.2 283 156.60 159.48 0.002578 2.31 238.30 645.64 0.58

41249.1 283 155.63 157.81 0.005229 2.72 131.34 216.90 0.79

PRTW.09(a) - left

bank

41154.3 283 154.71 156.83 0.008576 3.09 92.93 99.69 0.98

41068.4 283 153.79 155.88 0.003324 2.02 244.12 867.14 0.62

41014.1* 283 153.17 155.44 0.004515 2.40 160.61 422.00 0.73

40905.5 283 151.94 154.59 0.004240 2.33 173.28 444.00 0.70

40653.5* 283 150.18 152.46 0.004816 2.38 157.85 351.37 0.74

40401.6* 283 148.42 150.44 0.005534 2.30 150.84 412.86 0.78

40149.7* 283 146.66 148.20 0.010004 2.43 119.46 224.03 0.98

39897.8 283 144.93 146.96 0.001030 1.07 264.22 263.55 0.34




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

39660.8 283 144.91 146.34 0.005166 1.98 167.19 415.81 0.73

39352.2* 283 143.09 144.64 0.005564 2.09 150.89 356.95 0.76

39228.8* 283 142.36 143.94 0.005757 2.09 157.17 430.84 0.77

39043.7* 283 141.26 143.02 0.004228 2.05 158.34 314.53 0.68

38673.4* 283 139.07 140.86 0.007538 2.40 128.76 293.41 0.88

38179.7* 283 136.16 138.26 0.004000 1.90 170.45 318.02 0.66

37624.4* 283 132.87 135.05 0.007436 2.69 115.18 180.90 0.90

PRTW.09(c) - right

bank

37562.7 283 132.51 134.85 0.003854 1.96 169.95 273.43 0.65

37493.4 283 132.47 134.52 0.004572 2.15 140.13 266.18 0.71

37403 283 132.23 134.36 0.002158 1.48 221.92 381.72 0.49

37292.2 283 131.96 134.23 0.000705 0.99 332.72 478.22 0.29

37186.9 531 131.58 133.91 0.002483 1.97 319.69 643.00 0.55

37103.6 531 131.57 133.40 0.007295 2.79 193.81 292.52 0.90

37056.4 531 131.30 133.47 0.001470 1.36 474.82 560.97 0.41

36918.4 531 130.70 132.89 0.006892 2.48 225.17 339.87 0.86

36827 531 130.29 132.65 0.002553 1.88 315.86 554.06 0.55

36693.6 531 130.07 132.36 0.002433 1.63 356.29 515.99 0.52

36631.6 531 129.76 132.05 0.003717 2.10 291.06 461.38 0.65

36601.2* 531 129.64 132.00 0.003291 1.88 317.43 482.52 0.61

36510.1 531 129.29 131.80 0.002632 1.72 334.68 456.05 0.55

36370.3* 531 128.90 131.38 0.002692 1.85 332.44 492.80 0.56

36090.7* 531 128.14 130.53 0.002797 2.05 265.33 236.32 0.58

35951 531 127.75 129.92 0.004426 2.39 224.99 216.88 0.72

35914.6* 531 127.65 129.84 0.003431 2.16 249.83 234.55 0.64

PRTW.09(d) - right

bank

35878.2 531 127.55 129.79 0.002461 1.89 294.22 313.72 0.55

35845.8* 531 127.43 129.68 0.002595 2.01 290.92 375.24 0.57

35813.5 531 127.30 129.54 0.003156 2.24 274.47 415.19 0.63

35739.7 531 126.90 129.14 0.004963 2.72 210.50 256.30 0.78

35560.2* 531 126.43 128.44 0.003838 2.27 236.97 219.25 0.67

35201.3* 531 125.49 127.27 0.003159 1.79 305.85 373.49 0.59

34842.4* 531 124.55 126.26 0.002746 1.43 370.85 500.17 0.53

34663.0* 531 124.08 126.07 0.000773 1.00 571.79 617.16 0.30

34545 Bridge

34304.1 531 123.14 125.02 0.000821 0.96 590.74 731.74 0.31

34018.6 531 123.14 124.77 0.000871 1.01 558.21 732.94 0.32

33536.4 531 122.86 123.96 0.002833 1.76 302.12 305.96 0.56

33192.7* 531 121.79 123.05 0.002493 1.69 313.55 304.96 0.53

32849.1* 531 120.71 122.01 0.003533 1.88 281.84 303.43 0.62

32351.7* 531 118.78 120.58 0.002427 1.83 289.91 246.57 0.54

31949.2* 531 116.95 118.84 0.005948 2.90 183.09 155.51 0.85

31815.1 531 116.34 118.42 0.003348 2.43 339.55 722.35 0.65

PRTW.12(L/B) -

left bank

31772.1* 531 116.24 118.26 0.003610 2.36 296.22 1143.21 0.67

31643.3 531 115.95 117.82 0.005479 2.18 277.86 720.65 0.76

31504.9 531 115.33 117.42 0.001930 1.41 484.61 1389.09 0.46

31380 531 114.81 117.01 0.003207 2.03 396.92 1048.33 0.61

31216.8 531 114.31 116.48 0.003064 2.05 324.41 1331.86 0.60

31062.2 531 113.90 115.99 0.003522 1.81 471.82 1659.90 0.62

PRTW.12(R/B) -rightbank

31043.1* 531 113.85 115.90 0.004842 1.67 366.58 1166.30 0.68

30891.1 531 113.43 115.51 0.001808 1.17 619.59 2166.17 0.43

30667.1 531 112.55 114.80 0.004258 1.85 335.82 1180.20 0.67

30634.3* 531 112.50 114.74 0.003126 1.52 411.94 1127.48 0.57

30503.2 531 112.27 114.31 0.004012 2.02 400.58 1422.23 0.67

30135.6* 531 111.03 112.87 0.002751 1.56 395.32 1107.03 0.54

29890.5* 531 110.20 111.73 0.006948 2.13 280.37 828.87 0.83

29523 531 108.96 110.91 0.000713 0.81 698.28 1256.15 0.28

29348.3 531 108.96 110.73 0.001187 1.04 617.56 1769.30 0.36

28703.8* 531 107.61 109.92 0.001214 1.14 555.08 1254.61 0.37

28317.1* 531 106.79 109.56 0.000723 1.01 754.73 1228.61 0.30

28059.3 531 106.26 108.87 0.008234 2.28 252.70 576.47 0.90

27784.9* 531 105.55 107.21 0.001865 1.30 409.26 478.21 0.45

27236.1* 531 104.61 106.26 0.001617 1.54 424.59 619.18 0.44

26687.3* 531 102.56 104.28 0.011680 2.17 244.95 527.45 1.01




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

26138.5* 531 101.08 103.46 0.000584 0.93 641.73 1102.10 0.27

25864.2 531 100.34 103.23 0.000685 1.38 385.95 194.32 0.31

25476.1 531 100.34 102.48 0.003516 2.42 219.75 161.09 0.66

25134.9* 531 98.84 100.45 0.009098 3.03 174.99 187.30 1.00

24577 531 96.34 98.19 0.001690 1.48 462.01 1235.51 0.45

24270.3* 531 95.75 97.77 0.001256 1.32 538.93 1333.52 0.39

23656.9* 531 94.59 96.60 0.002870 1.67 342.79 653.66 0.56

23350.3 531 94.01 96.38 0.000485 0.98 845.28 957.66 0.25

Ratuwa 21224.7 1076 92.31 94.53 0.002321 1.87 620.64 832.06 0.53

(lower) 20888.1* 1076 91.58 93.74 0.002429 1.84 602.73 784.28 0.54

20551.6* 1076 90.86 92.98 0.002114 1.79 623.12 652.52 0.51

20215.1 1076 90.13 92.72 0.000567 1.101105.7

3 1028.88 0.27

19807.7* 1076 89.52 92.48 0.000557 1.201008.7

6 874.05 0.28

19595.7* 1076 89.22 92.30 0.000781 1.49 786.31 592.01 0.33

PRTW.02- rightbank

19387.7 1076 88.91 91.77 0.002643 2.65 500.14 738.74 0.61

19258.7 1076 88.67 91.39 0.002896 2.75 481.33 829.83 0.64

19064.7 1076 88.23 91.34 0.000644 1.53 831.44 647.04 0.31

18820.7 1076 88.19 91.04 0.001701 1.84 765.41 1160.68 0.47

18629.7 1076 87.75 90.91 0.000610 1.30 926.31 838.50 0.29

18471.3 1076 87.69 90.50 0.003151 2.41 474.35 441.41 0.64

PRTW.01(a) - left

bank

18453.7* 1076 87.64 90.47 0.003190 2.25 495.60 609.98 0.63

18245.7 1076 87.16 89.78 0.003426 2.44 679.72 1655.56 0.66

PRTW.01(b) - left

bank

18003.7 1076 86.71 89.49 0.000784 1.081151.0

5 1626.00 0.31

17698.7 1076 86.61 88.72 0.004071 2.61 465.77 1078.83 0.72

17307.7 1076 86.03 88.25 0.000907 1.361043.9

1 2047.40 0.35

16874.7* 1076 85.78 87.67 0.001962 1.48 814.84 1199.77 0.47

16729.7 1076 85.70 87.50 0.001091 1.021113.8

3 1642.94 0.34

16538.7 1076 85.12 86.94 0.003514 2.44 707.63 1593.13 0.67

16369.7* 1076 84.55 86.35 0.001774 1.37 893.77 1720.78 0.45

16201.7 1076 83.97 86.22 0.000623 0.931247.6

3 1740.47 0.27

15841.8* 1076 83.72 86.00 0.000590 0.941237.8

3 1662.67 0.27

15481.9* 1076 83.47 85.80 0.000554 0.941270.3

9 1426.58 0.26

15122.1* 1076 83.22 85.60 0.000555 0.961253.6

1 1374.66 0.26

14762.2* 1076 82.97 85.40 0.000555 0.981249.5

8 1414.29 0.27

14402.4* 1076 82.72 85.19 0.000601 1.041183.2

3 1186.26 0.28

14042.5* 1076 82.47 84.96 0.000717 1.081173.7

7 1337.34 0.30

13682.7 1076 82.21 84.17 0.005424 2.50 576.69 1113.61 0.79

13476.7 1076 80.02 82.30 0.002432 1.20 955.57 2026.63 0.49

13120.4* 1076 79.47 81.51 0.002062 1.14 984.29 1991.62 0.45

12407.9* 1076 78.36 80.15 0.001737 1.191011.1

7 2058.71 0.43

11695.4* 1076 77.25 78.87 0.001806 1.30 896.56 1766.14 0.44

10982.9* 1076 75.55 78.19 0.000638 0.901274.0

6 1673.20 0.27

10626.7 1076 75.20 78.03 0.000348 0.751500.6

0 1406.93 0.21

10180.7* 1076 75.01 77.82 0.000625 0.841290.0

2 1414.14 0.27

9979.7 1076 74.63 77.63 0.001157 1.011247.7

8 2061.54 0.35




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

9270.7* 1076 74.36 77.16 0.000434 0.921295.1

8 1678.99 0.24

8462.9 1076 74.06 76.73 0.000603 1.061159.0

5 1298.16 0.28

7995.9* 1076 73.55 76.42 0.000644 1.181034.3

9 1122.91 0.29

7555.9* 1076 73.05 76.03 0.001064 1.39 857.50 954.86 0.37

PRTW.08- rightbank

7333.9 1076 72.79 75.35 0.004611 2.60 554.47 2049.40 0.75

7095.2 1076 72.22 75.18 0.000738 1.101139.7

3 1489.77 0.30

6809.2 1076 72.10 74.94 0.000909 1.141038.9

3 1368.50 0.33

6650.2 1076 72.07 74.84 0.000580 0.931235.9

2 1496.24 0.27

6299.5 1076 71.73 74.59 0.000732 1.091125.3

9 1550.93 0.30

6033.5 1076 71.40 74.42 0.000612 1.031247.1

8 1807.41 0.28

5248.9* 1076 71.38 74.01 0.000448 0.981285.0

7 2395.39 0.24

4740.9 1494 71.37 73.70 0.000699 1.151572.0

8 2552.39 0.30

4394.04* 1494 70.94 73.46 0.000741 1.081621.3

2 2475.67 0.30

3526.9 1494 69.87 71.89 0.004399 2.63 744.66 1178.03 0.74

3171.9* 1494 68.97 71.46 0.000905 1.061470.1

2 1677.06 0.32

PRTW.06(L/B) -

left bank

2557.9 1494 67.48 70.31 0.002873 2.51 939.10 2110.95 0.62

2414.9 1494 67.30 70.10 0.001639 1.65 968.29 2133.43 0.45

2249.9 1494 66.60 69.94 0.000788 1.441167.8

2 1526.88 0.33

2153.1 1494 66.52 69.77 0.001619 1.83 951.18 1157.42 0.46

1923.1 1494 66.20 69.70 0.000332 1.021662.9

4 1627.81 0.22

1693.1 1494 66.11 69.59 0.000597 1.191490.0

2 1853.08 0.29

1457.1 1494 66.03 69.25 0.001923 1.88 972.28 1226.59 0.50

1230 1494 65.61 68.89 0.001380 1.791071.7

7 1505.78 0.43


729 1494 65.21 68.21 0.001249 1.84 942.44 1533.66 0.42

464 1494 64.77 67.74 0.002191 2.00 860.77 1297.08 0.53

330 1494 64.67 67.66 0.000870 1.201368.2

2 1662.08 0.33

161 1494 64.51 67.10 0.003432 2.68 727.52 1372.69 0.68

0 1494 64.15 66.52 0.004002 2.70 703.64 1182.92 0.72

Mawa 46403 545 213.68 215.46 0.008113 3.32 168.00 164.35 0.98

(upper) 46181.4* 545 210.96 212.52 0.008332 3.13 179.86 201.08 0.98

45959.8* 545 208.25 209.62 0.009044 2.89 190.50 240.68 0.99

45738.2* 545 205.53 206.74 0.009172 2.74 201.85 286.25 0.98

45516.6 545 202.82 203.90 0.008417 2.54 221.03 345.09 0.93

45251.1* 545 200.27 201.41 0.008149 2.65 216.16 318.84 0.93

44720.1* 545 195.16 196.48 0.009160 2.93 187.47 236.68 1.00

PRTW.03- leftbank

44454.6 545 192.62 194.22 0.005902 2.66 256.77 516.16 0.83

44322.7 545 190.49 192.82 0.004568 2.42 300.97 764.41 0.73

44222.6 545 188.84 191.48 0.006691 2.60 248.82 469.40 0.86

44121.3 545 187.61 189.70 0.006959 2.55 247.87 465.63 0.87

43975.3 545 185.55 187.96 0.007233 2.50 259.25 516.30 0.88

43602.5* 545 179.87 181.60 0.008894 2.48 236.21 408.06 0.95

43038.5 545 171.34 172.34 0.009361 2.34 245.69 521.96 0.95

42508.3* 545 167.88 168.93 0.004233 1.61 419.48 879.68 0.64

41713.2 545 162.69 163.12 0.014732 1.40 390.13 1922.71 0.99

41344.2* 545 159.70 160.79 0.003267 1.14 477.64 1034.13 0.54

40975.3 545 156.72 158.81 0.006537 2.61 253.86 492.20 0.85

40588.9* 545 151.88 154.09 0.003615 2.52 314.76 760.37 0.68




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

40098.0* 545 147.98 150.53 0.004824 3.11 228.21 329.96 0.80

PRTW.11- rightbank

39852.6 545 146.04 149.07 0.003207 3.01 277.31 442.90 0.67

39741 545 145.10 148.08 0.002966 2.82 291.63 613.57 0.64

39621.6 545 144.36 147.45 0.003027 2.66 336.87 696.44 0.64

39484.1 545 143.80 146.45 0.003335 2.64 311.72 687.68 0.66

39410.7 545 143.25 145.85 0.003017 2.49 357.45 884.24 0.63

39280.9 545 142.67 144.90 0.004585 2.88 228.40 420.68 0.77

39206.3 545 142.15 144.65 0.003144 2.40 292.55 819.79 0.64

39102 545 141.32 144.27 0.003655 2.49 325.07 791.22 0.68

38934.0* 545 140.40 143.25 0.003962 2.53 288.92 784.77 0.70

38598.0* 545 138.55 141.18 0.003511 2.57 314.34 700.33 0.67

38443 545 137.83 140.24 0.002343 1.94 462.14 1062.41 0.54

PRTW.10- leftbank

38430 545 137.63 140.12 0.003235 2.30 383.22 1062.31 0.64

38320.5 545 136.85 139.51 0.003492 2.24 298.71 786.86 0.65

38270.3 545 136.50 139.33 0.002470 2.25 271.91 862.84 0.57

38195.9 545 136.31 139.20 0.002629 2.39 437.17 1234.13 0.59

38070.9 545 135.73 137.93 0.003196 2.28 389.53 1078.35 0.63

PRTW.05(b) - right

bank

37878.1 545 134.37 136.67 0.004947 2.33 269.22 1000.89 0.75

37763.5 545 133.73 136.10 0.003872 2.30 270.04 892.82 0.68

37614.6 545 133.03 135.65 0.002773 2.32 424.48 1076.88 0.60

37533.6* 545 132.56 135.36 0.003152 2.41 365.14 954.48 0.64

PRTW.05(a) - right

bank

37452.6 545 132.09 134.99 0.003012 2.54 352.33 783.10 0.63

37323.5 545 131.32 133.84 0.005158 2.70 234.85 444.48 0.79

37212.2 545 130.73 133.39 0.003844 2.39 332.08 852.49 0.68

37109.1 545 130.06 132.69 0.004490 2.45 256.85 786.95 0.73

37029.4 545 129.81 132.44 0.003190 2.22 283.15 469.43 0.63

37001.7* 545 129.74 132.31 0.003704 2.33 288.17 591.09 0.67

36918.6 545 129.51 131.72 0.006610 2.90 210.13 406.28 0.88

36769.2* 545 128.75 130.98 0.004406 2.56 291.11 734.96 0.73

36470.4* 545 127.24 129.38 0.004296 2.68 239.82 475.56 0.73

36171.6* 545 125.74 127.53 0.007497 3.25 175.02 183.11 0.95

35872.9 545 124.23 126.09 0.003560 2.32 279.86 432.07 0.66

35549.4* 545 123.14 125.06 0.002852 2.21 318.09 683.97 0.60

35226.0* 545 122.06 123.55 0.006589 2.75 228.87 362.34 0.87

34757.3 545 120.43 122.57 0.000699 1.22 481.03 451.38 0.31

34349.0* 545 119.27 122.12 0.001411 1.63 341.15 197.92 0.37

34310.7 Bridge

34218.4* 545 118.89 121.72 0.002979 2.16 266.00 257.45 0.51

34087.8 545 118.50 121.33 0.002784 2.53 361.98 969.82 0.61

33962.4 545 118.49 120.85 0.002919 2.52 238.96 362.72 0.62

33853.4 545 117.47 120.61 0.002077 2.48 304.02 571.42 0.55

33777.2 545 117.26 120.53 0.001744 2.01 370.30 1038.56 0.49

33661.3 545 117.07 120.25 0.002354 2.42 385.20 932.00 0.57

33534.8 545 116.85 119.72 0.003471 2.93 264.62 572.75 0.69

33432.7 545 116.56 119.23 0.002987 2.13 346.12 1045.36 0.60

PRTW.04- leftbank

33305.6* 545 116.08 118.86 0.002777 2.06 318.57 782.87 0.58

33178.6 545 115.60 118.58 0.001956 1.80 379.24 858.98 0.49

33036.4 545 115.57 118.00 0.004526 2.76 250.16 890.31 0.75

32889.2 545 115.07 117.81 0.001439 1.62 386.07 759.66 0.43

32765.2 545 114.64 117.66 0.001411 1.53 440.43 779.77 0.42

32709.5 545 114.21 117.49 0.002429 1.87 368.64 1280.74 0.54

32559.4 545 114.05 116.74 0.005085 2.71 230.62 589.39 0.78

PRTW.13(R/B) -right

bank andPRTW.13

(L/B) -left bank

32442.4 545 113.68 116.21 0.004221 2.36 256.32 763.28 0.71

32342.3 545 113.20 116.06 0.001437 1.70 361.70 651.92 0.43


32190.3 545 113.01 115.63 0.003726 2.42 322.55 880.73 0.68

32070 545 112.53 115.25 0.002145 1.90 347.53 899.18 0.52




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

31907.2* 545 112.35 114.90 0.002207 1.87 345.05 811.52 0.52

31744.5* 545 112.18 114.47 0.002785 2.03 294.01 571.83 0.58

31256.3 545 111.66 113.87 0.000891 1.28 502.51 874.71 0.34

30967.1* 545 110.82 113.56 0.000902 1.55 436.21 677.33 0.36

30822.5 545 110.39 113.29 0.001473 2.05 337.02 750.10 0.46

30657.7* 545 110.19 113.02 0.001588 2.16 306.12 320.57 0.48

30328.1* 545 109.79 112.43 0.002084 2.17 299.28 525.97 0.53

30163.4 545 109.59 111.78 0.005385 3.12 198.50 495.42 0.83

29839.6* 545 108.79 110.64 0.003217 2.23 265.75 409.28 0.63

29515.9* 545 108.00 109.59 0.003699 2.14 293.54 729.73 0.66

28889.9 545 106.41 108.11 0.001806 1.49 403.41 710.26 0.46

28376.9* 545 105.30 107.31 0.001400 1.40 429.59 802.53 0.41

27863.9 545 104.20 106.22 0.002733 2.09 336.77 714.45 0.58

27605.9* 545 103.65 105.54 0.002689 1.89 305.00 340.46 0.56

27089.9* 545 102.54 104.27 0.002399 1.68 381.28 977.04 0.52

26831.9 545 101.99 103.73 0.001928 1.53 389.49 804.19 0.47

26584.4* 545 101.24 103.20 0.002045 1.61 390.04 1152.16 0.49

26336.9* 545 100.50 102.73 0.001679 1.53 450.55 948.89 0.45

25841.9 545 99.00 101.72 0.002028 1.79 378.82 860.64 0.50

25157.8 545 96.97 100.33 0.002386 1.90 368.62 785.31 0.54

PRTW.07- rightbank

25130.8* 545 96.94 100.26 0.001839 1.74 474.90 1035.87 0.48

25077 545 96.90 100.09 0.001960 1.81 472.41 840.53 0.49

24938.4 545 96.61 99.72 0.003027 2.43 349.18 820.17 0.63

24778.8 545 96.45 99.26 0.002983 2.44 325.25 625.76 0.62

24688 545 96.30 99.20 0.001404 1.51 435.17 565.96 0.42

24521.1 545 96.27 98.93 0.001808 1.51 377.83 513.69 0.46

24359.6 545 96.21 98.62 0.002005 1.61 350.91 414.30 0.49

24248.2 545 96.18 98.57 0.000589 0.90 647.91 783.53 0.27

24224.9 545 96.13 98.49 0.000719 0.96 632.44 944.78 0.29

24178.6 Bridge

24002.2 545 96.09 98.20 0.002417 1.88 319.20 587.92 0.54

23719.2 545 95.16 97.60 0.001919 1.78 327.20 380.83 0.49

23346.2 545 94.14 96.33 0.004845 2.51 288.86 604.98 0.76

22916.2 545 94.02 95.59 0.001235 1.09 511.66 694.45 0.37

22269.2 545 93.09 95.16 0.000476 1.01 962.12 1413.39 0.25

A.2 Modelling Results – Run 3 (50 year return period)


Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

Ratuwa 44391 283 185.47 187.16 0.006306 3.50 87.23 86.97 0.90

(upper) 44131.3 283 182.75 184.61 0.003232 2.46 115.25 79.74 0.64

43929.8 283 181.95 183.38 0.009795 2.88 98.26 119.56 1.01

43751.0* 283 179.02 180.82 0.009173 2.78 101.68 124.33 0.98

43572.2* 283 176.10 178.26 0.009513 2.77 101.99 128.96 1.00

43393.4* 283 173.17 175.72 0.009866 2.78 101.84 132.12 1.01

43214.6* 283 170.24 173.28 0.004192 3.27 112.23 137.65 0.76

43035.9 283 167.31 170.16 0.007224 3.80 75.88 60.71 0.97

42801.8* 283 165.83 169.12 0.003668 3.19 122.97 155.28 0.72

42567.8* 283 164.36 167.29 0.007505 2.58 117.55 186.55 0.90

42216.7* 283 162.14 164.73 0.007139 2.82 110.94 149.66 0.90

42099.7 283 161.40 163.84 0.007958 3.02 98.66 108.01 0.95

42072.0* 283 161.10 163.61 0.004189 2.50 122.61 137.65 0.71

PRTW.09(b) - left

bank

42044.4 283 160.79 163.60 0.001993 2.00 148.87 128.35 0.51

41985.6 283 160.41 163.01 0.006197 3.25 99.37 120.05 0.88

41885.4 283 159.71 162.10 0.007693 3.05 98.52 117.88 0.94

41746.5 283 158.75 161.10 0.005872 2.82 120.70 200.78 0.83




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

41617 283 157.55 160.39 0.003472 2.60 158.45 332.74 0.67

41509.5 283 157.34 159.79 0.004711 2.64 119.56 327.20 0.76

41410.2 283 156.60 159.48 0.002578 2.31 238.30 645.64 0.58

41249.1 283 155.63 157.81 0.005229 2.72 131.34 216.90 0.79

PRTW.09(a) - left

bank

41154.3 283 154.71 156.83 0.008576 3.09 92.93 99.69 0.98

41068.4 283 153.79 155.88 0.004854 2.38 158.48 439.50 0.75

41014.1* 283 153.17 155.47 0.004908 2.46 149.50 321.44 0.75

40905.5 283 151.94 154.59 0.004240 2.33 173.28 444.00 0.70

40653.5* 283 150.18 152.46 0.004816 2.38 157.85 351.37 0.74

40401.6* 283 148.42 150.44 0.005534 2.30 150.84 412.86 0.78

40149.7* 283 146.66 148.20 0.010004 2.43 119.46 224.03 0.98

39897.8 283 144.93 146.98 0.000964 1.05 269.61 263.80 0.33

39660.8 283 144.91 146.36 0.005633 2.03 161.04 381.31 0.76

39352.2* 283 143.09 144.65 0.005262 2.05 154.94 363.97 0.74

39228.8* 283 142.36 143.94 0.005975 2.12 154.48 431.84 0.78

39043.7* 283 141.26 143.03 0.004107 2.03 160.52 319.95 0.67

38673.4* 283 139.07 140.87 0.007757 2.42 129.40 299.68 0.89

38179.7* 283 136.16 138.27 0.003752 1.86 174.92 318.87 0.64

37624.4* 283 132.87 135.10 0.007750 2.73 112.86 183.29 0.92

PRTW.09(c) - right

bank

37562.7 283 132.51 134.89 0.003841 2.01 149.82 186.00 0.65

37493.4 283 132.47 134.55 0.005014 2.22 128.42 149.56 0.74

37403 283 132.23 134.39 0.002113 1.50 197.20 231.80 0.49

37292.2 283 131.96 134.26 0.000686 1.01 303.60 333.64 0.29

37186.9 531 131.58 133.95 0.002360 1.98 292.64 414.74 0.54

37103.6 531 131.57 133.45 0.007179 2.82 193.00 287.41 0.90

37056.4 531 131.30 133.48 0.001735 1.51 365.22 336.36 0.45

36918.4 531 130.70 132.91 0.006616 2.48 225.21 329.80 0.85

36827 531 130.29 132.68 0.002495 1.88 307.09 396.89 0.55

36693.6 531 130.07 132.37 0.002539 1.75 310.80 328.62 0.54

36631.6 531 129.76 132.05 0.003955 2.16 258.91 299.14 0.67

36601.2* 531 129.64 132.00 0.003538 1.94 286.84 353.85 0.63

36510.1 531 129.29 131.80 0.002631 1.72 334.73 456.08 0.55

36370.3* 531 128.90 131.38 0.002694 1.85 332.38 492.78 0.56

36090.7* 531 128.14 130.53 0.002794 2.05 265.41 236.34 0.58

35951 531 127.75 129.92 0.004450 2.40 224.59 216.79 0.72

35914.6* 531 127.65 129.84 0.003458 2.17 249.20 234.41 0.64

PRTW.09(d) - right

bank

35878.2 531 127.55 129.79 0.002419 1.90 283.82 251.49 0.54

35845.8* 531 127.43 129.68 0.002620 2.02 274.28 250.94 0.57

35813.5 531 127.30 129.54 0.003156 2.24 274.47 415.19 0.63

35739.7 531 126.90 129.14 0.004963 2.72 210.50 256.30 0.78

35560.2* 531 126.43 128.44 0.003838 2.27 236.97 219.25 0.67

35201.3* 531 125.49 127.27 0.003159 1.79 305.85 373.49 0.59

34842.4* 531 124.55 126.26 0.002746 1.43 370.85 500.17 0.53

34663.0* 531 124.08 126.07 0.000773 1.00 571.80 617.17 0.30

34545 Bridge

34304.1 531 123.14 125.02 0.000798 0.95 596.54 733.35 0.30

34018.6 531 123.14 124.79 0.000809 0.99 574.10 739.60 0.31

33536.4 531 122.86 123.98 0.003113 1.81 293.54 305.55 0.59

33192.7* 531 121.79 123.07 0.002359 1.67 318.82 305.02 0.52

32849.1* 531 120.71 122.02 0.003703 1.91 277.91 303.49 0.64




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

32351.7* 531 118.78 120.58 0.002371 1.82 291.94 246.64 0.53

31949.2* 531 116.95 119.01 0.005050 2.72 197.36 170.78 0.78

31815.1 531 116.34 118.53 0.003542 2.59 286.18 725.68 0.68

PRTW.12(L/B) - left

bank

31772.1* 531 116.24 118.43 0.003282 2.50 317.46 815.11 0.65

31643.3 531 115.95 117.90 0.006779 2.58 232.17 492.72 0.86

31504.9 531 115.33 117.48 0.001819 1.53 449.29 1040.38 0.46

31380 531 114.81 117.09 0.002904 2.03 346.57 671.94 0.59

31216.8 531 114.31 116.54 0.003846 2.13 364.52 1379.13 0.66

31062.2 531 113.90 116.12 0.001866 1.45 627.91 1922.10 0.46

PRTW.12(R/B) -

right bank

31043.1* 531 114.07 116.01 0.004432 1.67 363.86 882.63 0.66

30891.1 531 113.43 115.59 0.002033 1.32 505.55 1194.57 0.46

30667.1 531 112.55 114.84 0.004335 2.00 333.26 1151.95 0.68

30634.3* 531 112.50 114.74 0.004218 1.85 328.23 688.01 0.66

30503.2 531 112.27 114.31 0.004012 2.02 400.58 1422.23 0.67

30135.6* 531 111.03 112.87 0.002751 1.56 395.32 1107.03 0.54

29890.5* 531 110.20 111.73 0.006948 2.13 280.37 828.87 0.83

29523 531 108.96 110.91 0.000713 0.81 698.28 1256.15 0.28

29348.3 531 108.96 110.73 0.001187 1.04 617.56 1769.30 0.36

28703.8* 531 107.61 109.92 0.001214 1.14 555.08 1254.61 0.37

28317.1* 531 106.79 109.56 0.000723 1.01 754.73 1228.61 0.30

28059.3 531 106.26 108.87 0.008234 2.28 252.70 576.47 0.90

27784.9* 531 105.55 107.21 0.001865 1.30 409.26 478.21 0.45

27236.1* 531 104.61 106.26 0.001617 1.54 424.59 619.18 0.44

26687.3* 531 102.56 104.28 0.011680 2.17 244.95 527.45 1.01

26138.5* 531 101.08 103.46 0.000584 0.93 641.73 1102.10 0.27

25864.2 531 100.34 103.23 0.000685 1.38 385.95 194.32 0.31

25476.1 531 100.34 102.48 0.003516 2.42 219.75 161.09 0.66

25134.9* 531 98.84 100.45 0.009098 3.03 174.99 187.30 1.00

24577 531 96.34 98.19 0.001690 1.48 462.02 1235.52 0.45

24270.3* 531 95.75 97.77 0.001256 1.32 538.88 1333.47 0.39

23656.9* 531 94.59 96.60 0.002868 1.67 342.89 653.81 0.56

23350.3 531 94.01 96.38 0.000485 0.98 845.73 957.85 0.25

Ratuwa 21224.7 1076 92.31 94.53 0.002326 1.87 620.03 831.70 0.53

(lower) 20888.1* 1076 91.58 93.74 0.002438 1.84 601.76 783.40 0.54

20551.6* 1076 90.86 93.02 0.001901 1.74 651.86 822.18 0.49

20215.1 1076 90.13 92.82 0.000460 1.03 1201.41 1061.34 0.25

19807.7* 1076 89.52 92.63 0.000417 1.09 1144.81 956.17 0.24

19595.7* 1076 89.22 92.50 0.000553 1.33 910.12 667.99 0.29

PRTW.02 -right bank

19387.7 1076 88.91 91.98 0.002636 2.80 494.10 534.05 0.61

19258.7 1076 88.67 91.61 0.002636 2.91 486.31 578.90 0.62

19064.7 1076 88.23 91.51 0.000797 1.80 667.22 440.45 0.35

18820.7 1076 88.19 91.12 0.002134 2.23 554.15 633.70 0.54

18629.7 1076 87.75 91.00 0.000684 1.53 786.19 605.81 0.32

18471.3 1076 87.69 90.58 0.003452 2.47 462.15 439.85 0.66

PRTW.01(a) - left

bank

18453.7* 1076 87.64 90.47 0.004618 2.59 421.80 393.06 0.75

18245.7 1076 87.16 89.78 0.002883 2.49 613.07 951.04 0.62

PRTW.01(b) - left

bank

18003.7 1076 86.71 89.54 0.000880 1.37 843.58 966.20 0.34

17698.7 1076 86.61 88.78 0.003805 2.65 489.04 1054.05 0.70

17307.7 1076 86.03 88.38 0.000783 1.37 995.65 1397.95 0.33




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

16874.7* 1076 85.78 87.84 0.001977 1.53 756.08 1089.32 0.48

16729.7 1076 85.70 87.62 0.001485 1.33 863.58 1310.71 0.41

16538.7 1076 85.12 86.97 0.004170 2.63 649.90 1225.05 0.72

16369.7* 1076 84.55 86.35 0.002385 1.67 714.41 1210.92 0.52

16201.7 1076 83.97 86.23 0.000655 0.95 1228.50 1747.09 0.28

15841.8* 1076 83.72 86.00 0.000590 0.94 1237.83 1662.67 0.27

15481.9* 1076 83.47 85.80 0.000554 0.94 1270.39 1426.58 0.26

15122.1* 1076 83.22 85.60 0.000555 0.96 1253.61 1374.66 0.26

14762.2* 1076 82.97 85.40 0.000555 0.98 1249.58 1414.29 0.27

14402.4* 1076 82.72 85.19 0.000601 1.04 1183.23 1186.26 0.28

14042.5* 1076 82.47 84.96 0.000717 1.08 1173.77 1337.34 0.30

13682.7 1076 82.21 84.17 0.005424 2.50 576.69 1113.61 0.79

13476.7 1076 80.02 82.30 0.002432 1.20 955.57 2026.63 0.49

13120.4* 1076 79.47 81.51 0.002062 1.14 984.29 1991.62 0.45

12407.9* 1076 78.36 80.15 0.001737 1.19 1011.17 2058.71 0.43

11695.4* 1076 77.25 78.87 0.001806 1.30 896.56 1766.14 0.44

10982.9* 1076 75.55 78.19 0.000638 0.90 1274.10 1673.23 0.27

10626.7 1076 75.20 78.03 0.000348 0.75 1500.63 1406.96 0.21

10180.7* 1076 75.01 77.82 0.000625 0.84 1290.08 1414.15 0.27

9979.7 1076 74.63 77.63 0.001157 1.01 1247.94 2061.57 0.35

9270.7* 1076 74.36 77.16 0.000433 0.92 1296.40 1680.29 0.24

8462.9 1076 74.06 76.73 0.000598 1.06 1163.28 1299.59 0.28

7995.9* 1076 73.55 76.43 0.000633 1.17 1043.06 1128.74 0.29

7555.9* 1076 73.05 76.06 0.000996 1.36 882.06 969.65 0.36

PRTW.08 -right bank

7333.9 1076 72.79 75.39 0.004364 2.60 478.16 884.35 0.73

7095.2 1076 72.22 75.19 0.000826 1.21 896.78 681.13 0.32

6809.2 1076 72.10 74.95 0.000904 1.18 955.72 919.52 0.33

6650.2 1076 72.07 74.85 0.000585 0.96 1147.48 1098.26 0.27

6299.5 1076 71.73 74.61 0.000715 1.10 1061.09 1141.87 0.30

6033.5 1076 71.40 74.42 0.000653 1.11 1135.37 1257.23 0.29

5248.9* 1076 71.38 74.01 0.000448 0.98 1286.64 2401.14 0.24

4740.9 1494 71.37 73.71 0.000695 1.14 1576.84 2557.29 0.30

4394.04* 1494 70.94 73.46 0.000730 1.07 1632.68 2486.45 0.30

3526.9 1494 69.87 71.90 0.004358 2.63 743.73 1191.23 0.73

3171.9* 1494 68.97 71.53 0.000808 1.02 1533.31 1723.96 0.31

PRTW.06(L/B) - left

bank

2557.9 1494 67.48 70.39 0.002999 2.60 775.85 1373.87 0.64

2414.9 1494 67.30 70.19 0.001638 1.70 955.73 1508.42 0.46

2249.9 1494 66.60 70.04 0.000783 1.47 1095.15 1191.95 0.33

2153.1 1494 66.52 69.84 0.001594 1.97 811.88 727.65 0.47

1923.1 1494 66.20 69.78 0.000374 1.06 1555.23 1262.96 0.23

1693.1 1494 66.11 69.65 0.000647 1.23 1340.28 1391.78 0.30

1457.1 1494 66.03 69.26 0.002021 2.00 847.93 868.66 0.51

1230 1494 65.61 68.99 0.001074 1.64 1229.82 1694.61 0.39

PRTW.06(R/B) -

right bank

729 1494 65.21 68.33 0.001355 1.88 933.94 1203.77 0.44

464 1494 64.77 67.85 0.002151 2.05 895.55 1293.87 0.53

330 1494 64.67 67.68 0.001319 1.57 1069.81 1101.45 0.41

161 1494 64.51 67.10 0.003432 2.68 727.52 1372.69 0.68

0 1494 64.15 66.52 0.004002 2.70 703.64 1182.92 0.72

Mawa 46403 545 213.68 215.46 0.008113 3.32 168.00 164.35 0.98

(upper) 46181.4* 545 210.96 212.52 0.008335 3.13 179.83 201.06 0.98

45959.8* 545 208.25 209.62 0.009041 2.89 190.52 240.69 0.99




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

45738.2* 545 205.53 206.74 0.009173 2.74 201.85 286.25 0.98

45516.6 545 202.82 203.92 0.007534 2.45 229.63 351.22 0.89

45251.1* 545 200.27 201.42 0.008902 2.73 210.10 318.89 0.97

44720.1* 545 195.16 196.59 0.007621 2.77 201.36 264.13 0.92

PRTW.03 -left bank

44454.6 545 192.62 194.23 0.008452 3.18 174.80 180.88 0.98

44322.7 545 190.49 192.84 0.006584 3.02 202.14 318.23 0.88

44222.6 545 188.84 191.54 0.007521 3.08 189.08 240.43 0.93

44121.3 545 187.61 189.74 0.009295 3.05 178.88 193.67 1.01

43975.3 545 185.55 188.02 0.009477 2.98 183.09 207.39 1.01

43602.5* 545 179.87 181.60 0.008894 2.48 236.21 408.06 0.95

43038.5 545 171.34 172.34 0.009361 2.34 245.69 521.96 0.95

42508.3* 545 167.88 168.93 0.004233 1.61 419.48 879.68 0.64

41713.2 545 162.69 163.12 0.014732 1.40 390.13 1922.71 0.99

41344.2* 545 159.70 160.79 0.003267 1.14 477.64 1034.13 0.54

40975.3 545 156.72 158.81 0.006537 2.61 253.86 492.20 0.85

40588.9* 545 151.88 154.09 0.003615 2.52 314.76 760.37 0.68

40098.0* 545 147.98 150.53 0.004824 3.11 228.21 329.96 0.80

PRTW.11 -right bank

39852.6 545 146.04 149.14 0.002987 3.01 282.24 424.83 0.65

39741 545 145.10 148.08 0.003704 3.06 234.65 388.40 0.72

39621.6 545 145.29 147.61 0.004439 3.17 261.07 343.37 0.76

39484.1 545 143.80 146.47 0.004838 3.31 207.50 305.31 0.80

39410.7 545 143.25 145.88 0.003660 2.82 286.91 498.76 0.69

39280.9 545 142.67 144.93 0.004453 2.89 221.29 291.68 0.75

39206.3 545 142.15 144.65 0.003532 2.51 255.91 521.26 0.67

39102 545 141.32 144.27 0.003655 2.49 325.07 791.22 0.68

38934.0* 545 140.40 143.25 0.003962 2.53 288.92 784.77 0.70

38598.0* 545 138.55 141.18 0.003511 2.57 314.34 700.33 0.67

38443 545 137.83 140.48 0.001002 1.42 675.20 1187.53 0.36

PRTW.10 -left bank

38430 545 137.63 140.28 0.002720 2.37 363.67 652.03 0.59

38320.5 545 136.85 139.77 0.004224 2.88 274.28 426.32 0.73

38270.3 545 136.50 139.53 0.003057 2.79 258.34 433.42 0.64

38195.9 545 136.31 139.42 0.003167 2.78 393.35 731.04 0.65

38070.9 545 135.73 137.93 0.003196 2.28 389.53 1078.35 0.63

PRTW.05(b) - right

bank

37878.1 545 134.37 136.87 0.004918 2.33 265.18 505.80 0.74

37763.5 545 133.73 136.28 0.004224 2.31 280.98 477.55 0.70

37614.6 545 133.03 135.65 0.003633 2.65 298.43 553.09 0.69

37533.6* 545 132.56 135.43 0.003084 2.43 353.24 985.73 0.63

PRTW.05(a) - right

bank

37452.6 545 132.09 135.00 0.004160 2.93 242.36 430.75 0.74

37323.5 545 132.09 134.02 0.004854 2.73 256.03 470.64 0.77

37212.2 545 131.05 133.42 0.005380 2.75 254.39 464.33 0.80

37109.1 545 130.06 132.75 0.004809 2.50 245.09 436.47 0.75

37029.4 545 129.81 132.45 0.003798 2.35 255.10 334.87 0.68

37001.7* 545 129.74 132.31 0.004165 2.43 256.55 422.62 0.71

36918.6 545 129.51 131.72 0.006610 2.90 210.13 406.28 0.88

36769.2* 545 128.75 130.98 0.004406 2.56 291.11 734.96 0.73

36470.4* 545 127.24 129.38 0.004296 2.68 239.82 475.56 0.73

36171.6* 545 125.74 127.53 0.007497 3.25 175.02 183.11 0.95

35872.9 545 124.23 126.09 0.003560 2.32 279.86 432.07 0.66

35549.4* 545 123.14 125.06 0.002852 2.21 318.09 683.97 0.60

35226.0* 545 122.06 123.55 0.006589 2.75 228.87 362.34 0.87

34757.3 545 120.43 122.57 0.000699 1.22 481.03 451.38 0.31




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

34349.0* 545 119.27 122.12 0.001411 1.63 341.15 197.92 0.37

34310.7 Bridge

34218.4* 545 118.89 121.72 0.002979 2.16 266.00 257.45 0.51

34087.8 545 118.50 121.33 0.002784 2.53 361.98 969.82 0.61

33962.4 545 118.49 120.85 0.002919 2.52 238.95 362.71 0.62

33853.4 545 117.47 120.61 0.002077 2.48 303.95 571.39 0.55

33777.2 545 117.26 120.53 0.001745 2.01 370.04 1038.28 0.49

33661.3 545 117.07 120.25 0.002350 2.42 385.64 932.49 0.57

33534.8 545 116.85 119.72 0.003471 2.93 264.62 572.75 0.69

33432.7 545 116.56 119.30 0.003071 2.15 349.49 1143.81 0.61

PRTW.04 -left bank

33305.6* 545 116.08 118.93 0.002548 2.15 317.30 605.57 0.57

33178.6 545 115.60 118.61 0.002312 2.14 308.33 516.53 0.55

33036.4 545 115.57 118.02 0.004433 2.88 220.04 463.28 0.75

32889.2 545 115.07 117.89 0.001274 1.62 373.58 444.76 0.41

32765.2 545 114.64 117.74 0.001343 1.60 384.94 502.61 0.42

32709.5 545 114.21 117.60 0.002035 1.88 372.28 674.36 0.51

32559.4 545 114.23 116.92 0.004952 2.75 234.09 359.13 0.77

PRTW.13(R/B) -

right bankand

PRTW.13(L/B) - left

bank

32442.4 545 113.68 116.41 0.003744 2.47 228.88 193.00 0.68

32342.3 545 113.20 116.15 0.002136 2.22 254.45 212.00 0.54

PRTW.13(R/B) -

right bank

32190.3 545 113.01 115.66 0.004576 2.61 255.20 472.54 0.75

32070 545 112.53 115.29 0.003178 2.14 281.34 446.75 0.62

31907.2* 545 112.35 114.90 0.002207 1.87 345.05 811.52 0.52

31744.5* 545 112.18 114.47 0.002785 2.03 294.01 571.83 0.58

31256.3 545 111.66 113.87 0.000891 1.28 502.51 874.71 0.34

30967.1* 545 110.82 113.56 0.000902 1.55 436.21 677.33 0.36

30822.5 545 110.39 113.29 0.001473 2.05 337.02 750.10 0.46

30657.7* 545 110.19 113.02 0.001588 2.16 306.12 320.57 0.48

30328.1* 545 109.79 112.43 0.002084 2.17 299.28 525.97 0.53

30163.4 545 109.59 111.78 0.005385 3.12 198.50 495.42 0.83

29839.6* 545 108.79 110.64 0.003217 2.23 265.75 409.28 0.63

29515.9* 545 108.00 109.59 0.003699 2.14 293.54 729.73 0.66

28889.9 545 106.41 108.11 0.001806 1.49 403.41 710.26 0.46

28376.9* 545 105.30 107.31 0.001400 1.40 429.59 802.53 0.41

27863.9 545 104.20 106.22 0.002733 2.09 336.77 714.45 0.58

27605.9* 545 103.65 105.54 0.002689 1.89 305.00 340.46 0.56

27089.9* 545 102.54 104.27 0.002399 1.68 381.29 977.08 0.52

26831.9 545 101.99 103.73 0.001922 1.53 390.21 807.35 0.47

26584.4* 545 101.24 103.20 0.002074 1.61 385.70 1134.13 0.49

26336.9* 545 100.50 102.80 0.001291 1.40 525.45 1119.78 0.40

25841.9 545 99.00 101.72 0.002889 2.00 332.77 851.15 0.59

25157.8 545 96.97 100.45 0.001593 1.65 449.32 809.79 0.45

PRTW.07 -right bank

25130.8* 545 96.94 100.36 0.001710 1.74 408.69 592.96 0.47

25077 545 96.90 100.20 0.001757 1.81 407.02 503.92 0.48




Dis-charge

MinCh El

W.S.Elev

E.G.Slope

VelChnl

FlowArea

TopWidth

Frou-de

[m3/s] [m] [m] [m/m] [m/s] [m2] [m] [-]

24938.4 545 96.61 99.74 0.004147 2.75 261.94 485.22 0.73

24778.8 545 96.45 99.30 0.003086 2.52 265.20 315.94 0.64

24688 545 96.30 99.25 0.001443 1.64 383.02 401.56 0.43

24521.1 545 96.27 98.95 0.001963 1.72 328.39 335.53 0.49

24359.6 545 96.21 98.64 0.002014 1.73 321.24 293.08 0.49

24248.2 545 96.18 98.57 0.000804 1.08 531.87 585.29 0.31

24224.9 545 96.13 98.49 0.000719 0.96 632.44 944.78 0.29

24178.6 Bridge

24002.2 545 96.09 98.20 0.002417 1.88 319.20 587.92 0.54

23719.2 545 95.16 97.60 0.001919 1.78 327.20 380.83 0.49

23346.2 545 94.14 96.33 0.004845 2.51 288.86 604.98 0.76

22916.2 545 94.02 95.59 0.001235 1.09 511.66 694.45 0.37

22269.2 545 93.09 95.16 0.000476 1.01 962.13 1413.40 0.25

A.3 Comparison modelling results 1 per 50 years return period

RiverRiver

Station

Change: Run 3 - Run 2

RiverRiver

Station


Waterlevel

Velo-city

Topwidth

Waterlevel

Velo-city Top width

[cm] [m/s] [m] [cm] [m/s] [m]

Ratuwa_Upper 44391 0.00 0.00 0.00 Ratuwa_Lower 8462.9 0.00 0.00 1.43

Ratuwa_Upper 44131.3 0.00 0.00 0.00 Ratuwa_Lower 7995.9* 1.00 -0.01 5.83


Ratuwa_Upper 43751.0* 0.00 0.00 0.00 Ratuwa_Lower 7333.9 4.00 0.00 -1165.05




Ratuwa_Upper 43035.9 0.00 0.00 0.00 Ratuwa_Lower 6299.5 2.00 0.01 -409.06


Ratuwa_Upper 42567.8* 0.00 0.00 0.00 Ratuwa_Lower 5248.9* 0.00 0.00 5.75

Ratuwa_Upper 42216.7* 0.00 0.00 0.00 Ratuwa_Lower 4740.9 1.00 -0.01 4.90


Ratuwa_Upper 42072.0* 0.00 0.00 0.00 Ratuwa_Lower 3526.9 1.00 0.00 13.20





Ratuwa_Upper 41617 0.00 0.00 0.00 Ratuwa_Lower 2153.1 7.00 0.14 -429.77




Ratuwa_Upper 41154.3 0.00 0.00 0.00 Ratuwa_Lower 1230 10.00 -0.15 188.83

Ratuwa_Upper 41068.4 0.00 0.36 -427.64 Ratuwa_Lower 729 12.00 0.04 -329.89

Ratuwa_Upper 41014.1* 3.00 0.06 -100.56 Ratuwa_Lower 464 11.00 0.05 -3.21

Ratuwa_Upper 40905.5 0.00 0.00 0.00 Ratuwa_Lower 330 2.00 0.37 -560.63

Ratuwa_Upper 40653.5* 0.00 0.00 0.00 Ratuwa_Lower 161 0.00 0.00 0.00

Ratuwa_Upper 40401.6* 0.00 0.00 0.00 Ratuwa_Lower 0 0.00 0.00 0.00

Ratuwa_Upper 40149.7* 0.00 0.00 0.00 Mawa_Upper 46403 0.00 0.00 0.00

Ratuwa_Upper 39897.8 2.00 -0.02 0.25 Mawa_Upper 46181.4* 0.00 0.00 -0.02

Ratuwa_Upper 39660.8 2.00 0.05 -34.50 Mawa_Upper 45959.8* 0.00 0.00 0.01

Ratuwa_Upper 39352.2* 1.00 -0.04 7.02 Mawa_Upper 45738.2* 0.00 0.00 0.00

Ratuwa_Upper 39228.8* 0.00 0.03 1.00 Mawa_Upper 45516.6 2.00 -0.09 6.13



RiverRiver

Station


RiverRiver

Station


Waterlevel

Velo-city

Topwidth

Waterlevel

Velo-city Top width

[cm] [m/s] [m] [cm] [m/s] [m]

Ratuwa_Upper 39043.7* 1.00 -0.02 5.42 Mawa_Upper 45251.1* 1.00 0.08 0.05

Ratuwa_Upper 38673.4* 1.00 0.02 6.27 Mawa_Upper 44720.1* 11.00 -0.16 27.45

Ratuwa_Upper 38179.7* 1.00 -0.04 0.85 Mawa_Upper 44454.6 1.00 0.52 -335.28

Ratuwa_Upper 37624.4* 5.00 0.04 2.39 Mawa_Upper 44322.7 2.00 0.60 -446.18

Ratuwa_Upper 37562.7 4.00 0.05 -87.43 Mawa_Upper 44222.6 6.00 0.48 -228.97


Ratuwa_Upper 37403 3.00 0.02 -149.92 Mawa_Upper 43975.3 6.00 0.48 -308.91


Ratuwa_Upper 37186.9 4.00 0.01 -228.26 Mawa_Upper 43038.5 0.00 0.00 0.00




Ratuwa_Upper 36827 3.00 0.00 -157.17 Mawa_Upper 40975.3 0.00 0.00 0.00



Ratuwa_Upper 36601.2* 0.00 0.06 -128.67 Mawa_Upper 39852.6 7.00 0.00 -18.07

Ratuwa_Upper 36510.1 0.00 0.00 0.03 Mawa_Upper 39741 0.00 0.24 -225.17



Ratuwa_Upper 35951 0.00 0.01 -0.09 Mawa_Upper 39410.7 3.00 0.33 -385.48



Ratuwa_Upper 35845.8* 0.00 0.01 -124.30 Mawa_Upper 39102 0.00 0.00 0.00

Ratuwa_Upper 35813.5 0.00 0.00 0.00 Mawa_Upper 38934.0* 0.00 0.00 0.00


Ratuwa_Upper 35560.2* 0.00 0.00 0.00 Mawa_Upper 38443 24.00 -0.52 125.12

Ratuwa_Upper 35201.3* 0.00 0.00 0.00 Mawa_Upper 38430 16.00 0.07 -410.28



Ratuwa_Upper 34545 0.00 0.00 0.00 Mawa_Upper 38195.9 22.00 0.39 -503.09

Ratuwa_Upper 34304.1 0.00 -0.01 1.61 Mawa_Upper 38070.9 0.00 0.00 0.00

Ratuwa_Upper 34018.6 2.00 -0.02 6.66 Mawa_Upper 37878.1 20.00 0.00 -495.09



Ratuwa_Upper 32849.1* 1.00 0.03 0.06 Mawa_Upper 37533.6* 7.00 0.02 31.25


Ratuwa_Upper 31949.2* 17.00 -0.18 15.27 Mawa_Upper 37323.5 18.00 0.03 26.16

Ratuwa_Upper 31815.1 11.00 0.16 3.33 Mawa_Upper 37212.2 3.00 0.36 -388.16



Ratuwa_Upper 31504.9 6.00 0.12 -348.71 Mawa_Upper 37001.7* 0.00 0.10 -168.47

Ratuwa_Upper 31380 8.00 0.00 -376.39 Mawa_Upper 36918.6 0.00 0.00 0.00


Ratuwa_Upper 31062.2 13.00 -0.36 262.20 Mawa_Upper 36470.4* 0.00 0.00 0.00

Ratuwa_Upper 31043.1* 11.00 0.00 -283.67 Mawa_Upper 36171.6* 0.00 0.00 0.00



Ratuwa_Upper 30634.3* 0.00 0.33 -439.47 Mawa_Upper 35226.0* 0.00 0.00 0.00

Ratuwa_Upper 30503.2 0.00 0.00 0.00 Mawa_Upper 34757.3 0.00 0.00 0.00

Ratuwa_Upper 30135.6* 0.00 0.00 0.00 Mawa_Upper 34349.0* 0.00 0.00 0.00



RiverRiver

Station


RiverRiver

Station


Waterlevel

Velo-city

Topwidth

Waterlevel

Velo-city Top width

[cm] [m/s] [m] [cm] [m/s] [m]

Ratuwa_Upper 29890.5* 0.00 0.00 0.00 Mawa_Upper 34310.7 0.00 0.00 0.00

Ratuwa_Upper 29523 0.00 0.00 0.00 Mawa_Upper 34218.4* 0.00 0.00 0.00

Ratuwa_Upper 29348.3 0.00 0.00 0.00 Mawa_Upper 34087.8 0.00 0.00 0.00







Ratuwa_Upper 26138.5* 0.00 0.00 0.00 Mawa_Upper 33305.6* 7.00 0.09 -177.30




Ratuwa_Upper 24577 0.00 0.00 0.01 Mawa_Upper 32765.2 8.00 0.07 -277.16




Ratuwa_Lower 21224.7 0.00 0.00 -0.36 Mawa_Upper 32342.3 9.00 0.52 -439.92

Ratuwa_Lower 20888.1* 0.00 0.00 -0.88 Mawa_Upper 32190.3 3.00 0.19 -408.19

Ratuwa_Lower 20551.6* 4.00 -0.05 169.66 Mawa_Upper 32070 4.00 0.24 -452.43

Ratuwa_Lower 20215.1 10.00 -0.07 32.46 Mawa_Upper 31907.2* 0.00 0.00 0.00

Ratuwa_Lower 19807.7* 15.00 -0.11 82.12 Mawa_Upper 31744.5* 0.00 0.00 0.00

Ratuwa_Lower 19595.7* 20.00 -0.16 75.98 Mawa_Upper 31256.3 0.00 0.00 0.00

Ratuwa_Lower 19387.7 21.00 0.15 -204.69 Mawa_Upper 30967.1* 0.00 0.00 0.00

Ratuwa_Lower 19258.7 22.00 0.16 -250.93 Mawa_Upper 30822.5 0.00 0.00 0.00





Ratuwa_Lower 18453.7* 0.00 0.34 -216.92 Mawa_Upper 29515.9* 0.00 0.00 0.00





Ratuwa_Lower 16874.7* 17.00 0.05 -110.45 Mawa_Upper 27089.9* 0.00 0.00 0.04


Ratuwa_Lower 16538.7 3.00 0.19 -368.08 Mawa_Upper 26584.4* 0.00 0.00 -18.03

Ratuwa_Lower 16369.7* 0.00 0.30 -509.86 Mawa_Upper 26336.9* 7.00 -0.13 170.89

Ratuwa_Lower 16201.7 1.00 0.02 6.62 Mawa_Upper 25841.9 0.00 0.21 -9.49

Ratuwa_Lower 15841.8* 0.00 0.00 0.00 Mawa_Upper 25157.8 12.00 -0.25 24.48

Ratuwa_Lower 15481.9* 0.00 0.00 0.00 Mawa_Upper 25130.8* 10.00 0.00 -442.91

Ratuwa_Lower 15122.1* 0.00 0.00 0.00 Mawa_Upper 25077 11.00 0.00 -336.61

Ratuwa_Lower 14762.2* 0.00 0.00 0.00 Mawa_Upper 24938.4 2.00 0.32 -334.95


Ratuwa_Lower 14042.5* 0.00 0.00 0.00 Mawa_Upper 24688 5.00 0.13 -164.40




Ratuwa_Lower 12407.9* 0.00 0.00 0.00 Mawa_Upper 24224.9 0.00 0.00 0.00




RiverRiver

Station


RiverRiver

Station


Waterlevel

Velo-city

Topwidth

Waterlevel

Velo-city Top width

[cm] [m/s] [m] [cm] [m/s] [m]


Ratuwa_Lower 10626.7 0.00 0.00 0.03 Mawa_Upper 23719.2 0.00 0.00 0.00


Ratuwa_Lower 9979.7 0.00 0.00 0.03 Mawa_Upper 22916.2 0.00 0.00 0.00




B. Design calculations

B.1 Standards and Guidelines

Various design standards and guides were used during the detailed design as discussed in

section 4.3. The following table outlines documents that were used for specific aspects of the

design.

Table 9: Standards and Guidelines

Aspect of design Standard or Guideline adopted

River

Width of river Various reviewed:▪ DWIDM Pocket Diary 2071 (2014 / 2015);▪ Guidelines for preparation of DPR for flood management works, Government ofIndia Central Water Commission (2018);▪ Technical Standards and Guidelines for Planning and Design, Volume I – FloodControl, JICA (2002)

Engineering judgement for final value

Gabionrevetments

Allowable slope Various reviewed:▪ Handbook for Flood Projection, Anti Erosion and River Training Works,Government of India Central Water Commission (2012)▪ Technical Standards and Guidelines for Planning and Design, Volume I –Flood Control, JICA (2002)

Length ▪ Handbook for Flood Projection, Anti Erosion and River Training Works,Government of India Central Water Commission (2012)

Thickness ▪ Handbook for Flood Projection, Anti Erosion and River Training Works,Government of India Central Water Commission (2012)

Stone size ▪ Handbook for Flood Projection, Anti Erosion and River Training Works,Government of India Central Water Commission (2012)

Stone grading ▪ CIRIA Manual on scour at bridges and other hydraulic structures, secondedition (2015).

Launchingaprons



Embankments

Cohesion Various reviewed:▪ Guidelines for preparation of DPR for flood management works, Government ofIndia Central Water Commission (2018)▪ Detailed Project Reports, People’s Embankments Programme (PEP)▪ British Standard BS 8002:1994 Code of practice for earth retainingstructures

Friction angle Various reviewed:▪ Guidelines for preparation of DPR for flood management works, Government ofIndia Central Water Commission (2018)▪ Detailed Project Reports, People’s Embankments Programme (PEP)▪ British Standard BS 8002:1994 Code of practice for earth retainingstructures



Unit weight Various reviewed:▪ Guidelines for preparation of DPR for flood management works, Government ofIndia Central Water Commission (2018)▪ Detailed Project Reports, People’s Embankments Programme (PEP)▪ British Standard BS 8004: 1986 Code of practice for foundations

Permeability Engineering judgement

Slope stability designcases and FOS

Various reviewed:▪ Guidelines for preparation of DPR for flood management works, Government ofIndia Central Water Commission (2018)▪ EM 1110-2-1902 Engineering and Design; Slope Stability, U.S. Army Corpsof Engineers (USACE) (2003)

Earthquakecoefficients

Various reviewed:▪ [DRAFT] Flood Control and Management Manual; Final Manual. Government ofNepal, Water and Energy Commission Secretariat (WECS) (June 2019)▪ Considerations in the Earthquake-Resistant Design of Earth and Rockfill Dams,Geotechnique, Vol. XXIX, No. 3, Sept. Seed, H. B. (1979)▪ Rationalizing the Seismic Coefficient Method, Hynes-Griffin Franklin (1984)▪ Eurocode 8: Design of structures for earthquake resistance (2004)▪ Nepal National Building Code, NBC 105:1994, Seismic Design of Buildings inNepal. Government of Nepal, Ministry of Physical Planning and Works,Department of Urban Development and Building Construction (1994)

Engineering judgement for final values

FOS ▪ EM 1110-2-1902 Engineering and Design; Slope Stability, U.S. Army Corpsof Engineers (USACE) (2003)

Compaction Engineering judgement

Freeboard Various reviewed:▪ DWIDM Pocket Diary 2071 (2014 / 2015)▪ Guidelines for preparation of DPR for flood management works, Government ofIndia Central Water Commission (2018)▪ Technical Standards and Guidelines for Planning and Design, Volume I – FloodControl, JICA (2002)▪ Accounting for residual uncertainty: an update to the fluvial freeboard guide.Environment Agency (2017)

Engineering judgement for final value

Bearing capacity

▪ British Standard BS 8004: 1986 Code of practice for foundationsSettlement Engineering judgement

Crest width ▪ DWIDM Pocket Diary 2071 (2014 / 2015)

Spurs

Location Engineering judgement

Height Engineering judgement


Side slope ▪ Handbook for Flood Projection, Anti Erosion and River Training Works,Government of India Central Water Commission (2012)

Spacing ▪ Handbook for Flood Projection, Anti Erosion and River Training Works,Government of India Central Water Commission (2012)

Launchingaprons



Drainage Arrangement Engineering judgement



Nature-basedsolutions

Grasses detailing Engineering judgement



B.2 Slope stability

B.2.1 Calculation of friction angles

The BS 8002:1994 method assumes that the angle of friction of “siliceous sands and gravels” can

be estimated from:

Table 10 contains the calculation.

Table 10: Calculation of friction angle as per BS 8002:1994

Soil type f 'b A B C f 'peak f 'cv

Sandy gravelcontaining fines

30 2 4 2 38˚ 36˚

Silty sand 30 2 1 2 35˚ 33˚Foundation material 30 0 0 0 30˚ 30˚

Assumptions include:

● Subangular particles for the fill materials.

● The sandy gravel with fines seems to be well graded; the silty sand is in between uniform

and moderate grading.

● Additional friction for potential compaction has been calculated, but it would be unwise to rely

on this for design – the materials may not get compacted, or even if they do, they may be

loosened up by successive flood events. It is common practice for slope stability calcs to

use f 'cv

● Foundation material is unknown so a basic 30˚ is assumed



B.2.2 Slope Stability

The following figures shows the slope stability results for the Maximum Water Level cases for

Model A; Sandy Gravel - 1 in 2 slopes with no intervention, and Model B; Silty Sand - 1 in 2 slopes

with no intervention.

Figure 21: Case A3 – Sandy Gravel – Maximum Water Level (countryside face)

Figure 22: Case B3 – Silty Sand – Maximum Water Level (countryside face)



The following figures show the slope stability results for the various cases for Model E Sandy

Gravel. The critical slip circle with the lowest Factor of Safety is marked in black. Circles in red

are below the target minimum FOS for that particular case. This is discussed more in Section

5.2.8.

Figure 23: Case E1 – Sandy Gravel – Normal Water Level with Surcharge (riverside face)



Figure 24: Case E2 – Sandy Gravel – Rapid Drawdown (2 days) (riverside face)

Figure 25: Case E3 – Sandy Gravel – Maximum Water Level (countryside face)



Figure 26: Case E3 – Sandy Gravel – Maximum Water Level (riverside face)

Figure 27: Case E4 – Sandy Gravel – Seismic Case



The following figures show the slope stability results for the various cases for Model G Silty Sand.

The critical slip circle with the lowest Factor of Safety is marked in black. Circles in red are below

the target minimum FOS for that particular case. This is discussed more in Section 5.2.8.

Figure 28: Case G1 – Silty Sand – Normal Water Level with Surcharge (riverside face)



Figure 29: Case G2 – Silty Sand – Rapid Drawdown (2 days) (riverside face)

Figure 30: Case G3 – Silty Sand – Maximum Water Level (countryside face)



Figure 31: Case G3 – Silty Sand – Maximum Water Level (riverside face)

Figure 32: Case E4 – Sandy Gravel – Seismic Case



The following figure shows the slope stability result for the Maximum Water Level case for Model

C; Sandy Gravel 2m.

Figure 33: Case C3 – Sandy Gravel – Maximum Water Level (countryside face)



B.3 Revetment, spurs and launching apron

GOVERNMENT OF NEPAL

MINISTRY OF ENERGY, WATER RESOURCES AND IRRIGATION DEPARTENT OF WATER

RESOURCES AND IRRIGATION

WATER RESOURCES PROJECT PREPARATORY FACILITY (WRPPF)

JAWALAKHEL, LALITPUR

Project: Preparation of Priority River Basin Flood Risk Management Project (GRANT NO:0299-

NEP)

Mawa Ratuwa Basin

1 Introduction

The following outlines the design calculations undertaken for the revetment, spur and launching

aprons proposed for the Mawa Ratuwa basin. The methodology follows the Handbook for Flood

Projection, Anti Erosion and River Training Works, Government of India Central Water

Commission (2012), referred to in this document as the Handbook. Text in italics and extracts of

equations are taken directly from the Handbook.

2 Revetment design

The proposed revetment design is a series of rock filled gabion mattresses. The revetment design

follows the methodology in the Handbook in section 4.5; Design of bank revetment. The

spreadsheets used for the calculations are attached; the following calculation methodology is

followed for each river station for each embankment.

2.1 Weight of stones

The weight of stones is calculated as follows, taken from the Handbook section 4.5.1. Note that

this stage is based on loose rip rap stone; the calculation is adapted for gabion mattresses in later

sections.

The weight of stones on slopes (W in kg) may be worked using the formula given below.

The velocity used is the maximum channel velocity from the HECRAS model for the relevant

revetment section. It was chosen to use these maximum velocities instead of the channel average

velocities in order for the design to be conservative, and to take into account higher velocities that

will occur at the outer bends; the HECRAS model is able to ascertain the difference in velocities

along the cross-section, hence the increased velocity at the bends at the model cross-sections



were able to be analysed. It should be noted that the left and right bank flood plain velocities from

the HECRAS model were looked at, however these were lower than the maximum main channel

velocities so were not used.

2.2 Minimum size of stones

The minimum size of stone (Ds) is then calculated based on the weight of stones, as follows,

taken from the Handbook section 4.5.2.

2.3 Thickness of pitching

The minimum thickness of pitching is calculated as follows, taken from Section 4.5.3.

For revetments made from gabions, this thickness corresponds to the minimum thickness of the

gabion mattress. As shown in the calculation, the design thickness of pitching has been selected

based on which available gabion thickness (i.e. 0.3 or 0.5m thick) is larger than the above

calculated thickness of pitching.

The weight of the gabion needs to be larger than the weight of stone calculated above. The

specific gravity of the crate is different from the boulders due to presence of voids. Porosity of the

crates (e) may be worked out using the following formula:

The opening in the wire net used for crates should not be larger than the smallest size of stone

used. The mass specific gravity of protection (Sm) can be worked out using the following

relationship

The D50 is calculated in the following section. For D50 of stone used in crates =150 mm, this gives

an e value as follows:

e = 0.245+ 0.0864/ (D50)0.21 = 0.2752

Sm = (1-e) *Ss = 1.9208

From this, the weight of the smallest proposed gabion (3mx1.5mx0.3m) is approximately 1450kg.

As expected, this is considerably larger than the required weight of stones calculated (largest is

around 12kg).



2.4 Stone grading

In order to design the stone grading, an additional calculation has been undertaken following the

CIRIA Manual on scour at bridges and other hydraulic structures, second edition (2015). This

follows the Escarmeia and May (1992) method for gabion mattresses (section 6.5.4.1 in the

guidance);

Velocity (m/s) V m/s 2.45 Chosen design velocity

Turbulence intensity r - 0.2 Around bends and at upstream ends of revetment

Turbulence coefficient C1 m 0.81 Value used for gabion mattresses

Near bed velocity Ub m/s 2.45 Chosen design velocity to be conservative

Relevant density s - 2.65 Density of rock/density of water

Stone size within gabion Dn50 m 0.150 Design D50

Chosen grading was therefore;

D15=100mm

D50=150mm

D100 = 200 mm

As can be seen from the spreadsheet, the velocity does exceed this value in certain locations. As

per the CIRIA manual, the maximum stone size should not exceed two thirds of the thickness of

pitching. As generally the chosen thickness of pitching is 0.3m, stone sizes above 200mm would

exceed this two thirds value. Therefore, the design velocity was lowered to 2.45m/s. The

maximum main channel velocities are already being used which will be higher than the cross-

sectional average velocities.

2.4 Slope

The gabion revetments will be placed at the slope angle of 1 in 2. The Handbook uses this slope

in the example calculations hence assumed acceptable. In addition, JICA guidelines (Technical

Standards and Guidelines for Planning and Design, Volume I – Flood Control, JICA (2002))

specify that 1 in 2 revetment slopes are standard (and up to 1 in 1.5 could be acceptable).

2.5 Launching apron

The size of Launching apron calculation follows section 4.9.4 in the Handbook.

Width of the launching apron depends upon the scour depth below HFL. Depth of scour below

HFL (D) may be worked out using the following formula:



The mean particle size is taken as 0.35mm (corresponding to medium sand) as from the

Morphology report.

Maximum scour depth (Dmax) below HFL and the thickness of the launching apron are then

calculated as follows;

The thickness of the launching apron is rounded up from ‘T’ due to size of available gabions.

3. Spur

The proposed spur design is a series of rock filled gabion mattresses. The spur design follows

the methodology in the Handbook in section 5; Design of Spurs/Groynes. The spreadsheets used

for the calculations are attached; the following calculation methodology is followed for each river

station for each embankment.

3.1 Arrangement of Spurs

In regards to the arrangement of spurs;

· The spurs have been designed based on the water level depth. For instance, if the

water depth is 2m then a 3 layered (0.75*3=2.25 m) spur was proposed. The maximum

height of spur proposed is 3 m (4*0.75m) even if the water depth is more than 3 m,

based on engineering judgement and standard practice. Therefore the spurs will be a

combination of submerged and unsubmerged, with a maximum height of 3m from the

river bed

· They are positioned at 90˚ to the banks

· The location of the spurs has been chosen on the outer bank of bends where velocities

are high (outer bends have been avoided where deposition was found to be notable on

the outer bend). In addition, in some straighter reaches spurs were designed based on

engineering judgement on the site visit, where notable bank erosion was occurring.

· The length of spurs is calculated by 2.5 multiplied by the calculated maximum depth of

scour. The length of spurs is not greater than 1/5th of the width of flow

· The spacing of the spurs is 2.5 multiplied by the calculated length of spur

· If using loose stone, the Handbook recommends 2H:1V or 3H:1V side slopes of the

spurs. This is not relevant as this design utilises gabions; a steeper slope of

approximately 1in1 is formed by the steps in the embankment



3.2 Launching Apron

The size of Launching apron calculation follows section 5.6.1 in the Handbook.

The scour depth is calculated using the same process as for the revetment launching apron

(please refer back to section 2.4 in this report).

Following this, the width of launching apron, if to be laid at LWL, is as follows;

The minimum thickness of launching apron (T) = 1.5* thickness of pitching (t). The thickness of

the launching apron is rounded up from ‘T’ due to size of available gabions.

3.3 Stone size and grading

The stone size and grading will be as calculated for the revetment design. It is noted that the

spurs are closer to the centre of the channel than the revetment at the banks, therefore will

experience higher velocities, however this has already been accounted for by using the maximum

channel velocity (as outlined in section 2.1).

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40

.25

0.3

0.3

51

.04

11

0.8

91

15

.29

2.7

63

.81

5.7

24

.44

0.3

8

PR

TW

.13

(L/B

)

32

44

2.4

0+

00

0 -

0+

09

05

45

2.4

70

.34

0.3

0.3

51

.04

11

0.8

91

16

.41

2.7

33

.81

5.7

24

.48

0.5

1

32

34

2.3

0+

09

0 -

0+

17

55

45

2.2

20

.27

0.3

0.3

51

.04

11

0.8

91

16

.15

2.9

53

.81

5.7

24

.15

0.4

1

0.3

0.3

0.4

0.4

0.5

0.4

0.3

0.3

0.4

0.3

0.4

0.6

6 64.5 6 66

0.3

6

0.5

0.5

0.5

0.8

0.5

6 6

0+

20

0 -

0+

61

0

0+

61

0 -

0+

95

0

0+

00

0 -

0+

05

5

0+

09

5 -

0+

26

5

0+

30

0 -

0+

50

0

0+

00

0 -

0+

37

0

0+

00

0 -

0+

10

5

0+

00

0 -

0+

08

5

0+

08

5 -

0+

50

0

0+

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0+

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0

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21

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65

0

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0

pa

ge

3 o

f 3

Pro

ject: P

repara

tion o

f P

riority

Riv

er

Basin

Flo

od R

isk M

anagem

ent P

roje

ct (G

RA

NT

NO

:0299-N

EP

)

Loca

tio

n

Re

fere

nce

Riv

er

Sta

tio

n

De

sig

n

Dis

cha

rge

(Q5

0)

m3/s

ec

Wa

ter

surf

ace

ele

va

tio

n

(m)

Wa

ter

de

pth

(m)

Ve

loci

ty

(m/s

ec)

Riv

er

be

d

lev

el

(m)

Se

dim

en

t

size

d(m

m)

Sil

t

fact

or(

f)=

1.7

6√

d

Sco

ur

de

pth

(D )

=

0.4

73

(Q/f

)1/3

Ma

xim

um

sco

ur

de

pth

(Dm

ax

)

be

low

HF

L

= 1

.5 *

D

Ma

xim

um

sco

ur

de

pth

(Dm

ax

)

be

low

LWL(

Ds)

=

Dm

ax

be

low

HF

L -

( H

FL-

LWL)

Wid

th o

f

lau

nch

ing

ap

ron

at

no

se =

2.5

*D

s (m

)

Pro

vid

e

wid

th o

f

lau

nch

ing

ap

ron

at

no

se (

m)

Wid

th o

f

lau

nch

ing

ap

ron

fro

m

no

se t

o

sha

nk

=

1.5

*D

s i

n

u/s

(F

irst

30

to 6

0 m

)

Pro

vid

e

wid

th o

f

lau

nch

ing

ap

ron

at

u/s

sp

ur

(m)

Wid

th o

f

lau

nch

ing

ap

ron

fro

m

no

se t

o s

ha

nk

= 1

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Ds

in

d/s

(F

irst

15

to 3

0 m

)

Pro

vid

e

wid

th o

f

lau

nch

ing

ap

ron

at

d/s

sp

ur

(m)

Re

qu

ire

d

Th

ick

ne

ss o

f

rev

etm

en

t (t

)

=V

2/2

g(S

m-1

)

(m)

Th

ick

ne

ss

of

lau

nch

ing

ap

ron

=

1.5

*t

(m)

Pro

vid

e

thic

kn

ess

of

lau

nch

ing

ap

ron

(m)

PR

TW

.01

(a)

18

45

3.7

*1

07

6.0

09

0.4

72

.83

2.5

98

7.6

40

.35

1.0

44

.78

7.1

74

.34

10

.86

6.5

14

.34

0.3

70

.56

18

24

5.7

10

76

.00

89

.78

2.6

22

.49

87

.16

0.3

51

.04

4.7

87

.17

4.5

51

1.3

86

.83

4.5

50

.34

0.5

1

PR

TW

.01

(b)

18

00

3.7

10

76

.00

89

.54

2.8

31

.37

86

.71

0.3

51

.04

4.7

87

.17

4.3

41

0.8

66

.51

4.3

40

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0.1

6

17

69

8.7

10

76

.00

88

.78

2.1

72

.65

86

.61

0.3

51

.04

4.7

87

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5.0

01

2.5

17

.50

5.0

00

.39

0.5

8

17

30

7.7

10

76

.00

88

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2.3

51

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86

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0.3

51

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4.7

87

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4.8

21

2.0

67

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4.8

20

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87

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08

7.8

42

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1.5

38

5.7

80

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1.0

44

.78

7.1

75

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12

.78

7.6

75

.11

0.1

30

.19

16

72

9.7

10

76

.00

87

.62

1.9

21

.33

85

.70

0.3

51

.04

4.7

87

.17

5.2

51

3.1

37

.88

5.2

50

.10

0.1

5

16

53

8.7

10

76

.00

86

.97

1.8

52

.63

85

.12

0.3

51

.04

4.7

87

.17

5.3

21

3.3

17

.98

5.3

20

.38

0.5

7

16

36

9.7

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07

6.0

08

6.3

51

.80

1.6

78

4.5

50

.35

1.0

44

.78

7.1

75

.37

13

.43

8.0

65

.37

0.1

50

.23

PR

TW

.02

19

38

7.7

10

76

.00

91

.98

3.0

72

.80

88

.91

0.3

51

.04

4.7

87

.17

4.1

01

0.2

66

.15

4.1

00

.43

0.6

5

19

25

8.7

10

76

.00

91

.61

2.9

42

.91

88

.67

0.3

51

.04

4.7

87

.17

4.2

31

0.5

86

.35

4.2

30

.47

0.7

0

19

06

4.7

10

76

.00

91

.51

3.2

81

.80

88

.23

0.3

51

.04

4.7

87

.17

3.8

99

.73

5.8

43

.89

0.1

80

.27

18

82

0.7

10

76

.00

91

.12

2.9

32

.23

88

.19

0.3

51

.04

4.7

87

.17

4.2

41

0.6

16

.36

4.2

40

.28

0.4

1

18

62

9.7

10

76

.00

91

.00

3.2

51

.53

87

.75

0.3

51

.04

4.7

87

.17

3.9

29

.81

5.8

83

.92

0.1

30

.19

PR

TW

.03

44

45

4.6

54

5.0

01

94

.23

1.6

13

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19

2.6

20

.35

1.0

43

.81

5.7

24

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10

.27

6.1

64

.11

0.5

60

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44

32

2.7

54

5.0

01

92

.84

2.3

53

.02

19

0.4

90

.35

1.0

43

.81

5.7

23

.37

8.4

25

.05

3.3

70

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0.7

6

44

22

2.6

54

5.0

01

91

.54

2.7

03

.08

18

8.8

40

.35

1.0

43

.81

5.7

23

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7.5

44

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3.0

20

.52

0.7

9

44

12

1.3

54

5.0

01

89

.74

2.1

33

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18

7.6

10

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1.0

43

.81

5.7

23

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8.9

75

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3.5

90

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0.7

7

43

97

5.3

54

5.0

01

88

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2.4

72

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18

5.5

50

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43

.81

5.7

23

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8.1

24

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3.2

50

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0.7

4

PR

TW

.04

33

30

5.6

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45

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11

8.9

32

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2.1

51

16

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0.3

51

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3.8

15

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2.8

77

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4.3

02

.87

0.2

60

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33

17

8.6

54

5.0

01

18

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3.0

12

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11

5.6

00

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1.0

43

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5.7

22

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6.7

74

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2.7

10

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0.3

8

33

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6.4

54

5.0

01

18

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2.4

52

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11

5.5

70

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43

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5.7

23

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8.1

74

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70

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0.6

9

32

88

9.2

54

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01

17

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2.8

21

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11

5.0

70

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43

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5.7

22

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7.2

44

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2.9

00

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0.2

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32

76

5.2

54

5.0

01

17

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3.1

01

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11

4.6

40

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43

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5.7

22

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6.5

43

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2.6

20

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1

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70

9.5

54

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01

17

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3.3

91

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10

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43

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5.7

22

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5.8

23

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2.3

30

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0.2

9

32

55

9.4

54

5.0

01

16

.92

2.6

92

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11

4.2

30

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43

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5.7

23

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7.5

74

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30

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0.6

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GO

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RN

ME

NT

OF

NE

PA

L

MIN

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OF

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GY

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ND

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ION

DE

PA

RT

EN

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R R

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OU

RC

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PR

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PR

EP

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F)

JA

WA

LA

KH

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n

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Ba

sin

: M

aw

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wa

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10

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7.5

0

pa

ge

1 o

f 3

PR

TW

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(a)

37

45

2.6

54

5.0

01

35

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2.9

12

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13

2.0

90

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43

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5.7

22

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7.0

24

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2.8

10

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0.7

1

37

32

3.5

54

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01

34

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1.9

32

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13

2.0

90

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43

.81

5.7

23

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9.4

75

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3.7

90

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0.6

2

37

21

2.2

54

5.0

01

33

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2.3

72

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13

1.0

50

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43

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5.7

23

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8.3

75

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3.3

50

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0.6

3

37

10

9.1

54

5.0

01

32

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2.6

92

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13

0.0

60

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43

.81

5.7

23

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7.5

74

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3.0

30

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0.5

2

37

02

9.4

54

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01

32

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2.6

42

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12

9.8

10

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43

.81

5.7

23

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7.6

94

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3.0

80

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0.4

6

37

00

1.7

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45

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13

2.3

12

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2.4

31

29

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0.3

51

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3.8

15

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3.1

57

.87

4.7

23

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0.3

30

.49

PR

TW

.05

(b)

37

87

8.1

54

5.0

01

36

.87

2.5

02

.33

13

4.3

70

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1.0

43

.81

5.7

23

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8.0

44

.83

3.2

20

.30

0.4

5

37

76

3.5

54

5.0

01

36

.28

2.5

52

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13

3.7

30

.35

1.0

43

.81

5.7

23

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7.9

24

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3.1

70

.30

0.4

4

37

61

4.6

54

5.0

01

35

.65

2.6

22

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13

3.0

30

.35

1.0

43

.81

5.7

23

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7.7

44

.65

3.1

00

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0.5

8

PR

TW

.06

(R/B

)

72

91

49

4.0

06

8.3

33

.12

1.8

86

5.2

10

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1.0

45

.33

8.0

04

.88

12

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7.3

24

.88

0.2

00

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46

41

49

4.0

06

7.8

53

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2.0

56

4.7

70

.35

1.0

45

.33

8.0

04

.92

12

.31

7.3

84

.92

0.2

30

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33

01

49

4.0

06

7.6

83

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1.5

76

4.6

70

.35

1.0

45

.33

8.0

04

.99

12

.48

7.4

94

.99

0.1

40

.20

PR

TW

.06

(L/B

)

25

57

.91

49

4.0

07

0.3

92

.91

2.6

06

7.4

80

.35

1.0

45

.33

8.0

05

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12

.73

7.6

45

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0.3

70

.56

24

14

.91

49

4.0

07

0.1

92

.89

1.7

06

7.3

00

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1.0

45

.33

8.0

05

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12

.78

7.6

75

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0.1

60

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22

49

.91

49

4.0

07

0.0

43

.44

1.4

76

6.6

00

.35

1.0

45

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8.0

04

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11

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6.8

44

.56

0.1

20

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21

53

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49

4.0

06

9.8

43

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1.9

76

6.5

20

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1.0

45

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8.0

04

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11

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7.0

24

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0.2

10

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19

23

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49

4.0

06

9.7

83

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1.0

66

6.2

00

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1.0

45

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8.0

04

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11

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6.6

34

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0.0

60

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16

93

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49

4.0

06

9.6

53

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1.2

36

6.1

10

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1.0

45

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8.0

04

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11

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6.6

94

.46

0.0

80

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14

57

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49

4.0

06

9.2

63

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2.0

06

6.0

30

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1.0

45

.33

8.0

04

.77

11

.93

7.1

64

.77

0.2

20

.33

PR

TW

.07

25

13

0.8

*5

45

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10

0.3

63

.42

1.7

49

6.9

40

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43

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5.7

22

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5.7

43

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2.3

00

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0.2

5

25

07

75

45

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10

0.2

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1.8

19

6.9

00

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43

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5.7

22

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6.0

43

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2.4

20

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0.2

7

24

93

8.4

54

5.0

09

9.7

43

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2.7

59

6.6

10

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43

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5.7

22

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6.4

73

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2.5

90

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0.6

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24

77

8.8

54

5.0

09

9.3

02

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2.5

29

6.4

50

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1.0

43

.81

5.7

22

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7.1

74

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2.8

70

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0.5

3

24

68

85

45

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99

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2.9

51

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96

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0.3

51

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3.8

15

.72

2.7

76

.92

4.1

52

.77

0.1

50

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24

52

1.1

54

5.0

09

8.9

52

.68

1.7

29

6.2

70

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1.0

43

.81

5.7

23

.04

7.5

94

.56

3.0

40

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0.2

5

24

35

9.6

54

5.0

09

8.6

42

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1.7

39

6.2

10

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1.0

43

.81

5.7

23

.29

8.2

24

.93

3.2

90

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0.2

5

24

24

8.2

54

5.0

09

8.5

72

.39

1.0

89

6.1

80

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1.0

43

.81

5.7

23

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8.3

24

.99

3.3

30

.06

0.1

0

PR

TW

.08

73

33

.91

07

6.0

07

5.3

92

.60

2.6

07

2.7

90

.35

1.0

44

.78

7.1

74

.57

11

.43

6.8

64

.57

0.3

70

.56

70

95

.21

07

6.0

07

5.1

92

.97

1.2

17

2.2

20

.35

1.0

44

.78

7.1

74

.20

10

.51

6.3

04

.20

0.0

80

.12

68

09

.21

07

6.0

07

4.9

52

.85

1.1

87

2.1

00

.35

1.0

44

.78

7.1

74

.32

10

.81

6.4

84

.32

0.0

80

.12

66

50

.21

07

6.0

07

4.8

52

.78

0.9

67

2.0

70

.35

1.0

44

.78

7.1

74

.39

10

.98

6.5

94

.39

0.0

50

.08

62

99

.51

07

6.0

07

4.6

12

.88

1.1

07

1.7

30

.35

1.0

44

.78

7.1

74

.29

10

.73

6.4

44

.29

0.0

70

.10

60

33

.51

07

6.0

07

4.4

23

.02

1.1

17

1.4

00

.35

1.0

44

.78

7.1

74

.15

10

.38

6.2

34

.15

0.0

70

.10

PR

TW

.09

(a)

41

15

4.3

28

3.0

01

56

.83

2.1

23

.09

15

4.7

10

.35

1.0

43

.06

4.6

02

.48

6.1

93

.71

2.4

80

.53

0.7

9

41

06

8.4

28

3.0

01

55

.88

2.0

92

.38

15

3.7

90

.35

1.0

43

.06

4.6

02

.51

6.2

63

.76

2.5

10

.31

0.4

7

41

01

4.1

*2

83

.00

15

5.4

72

.30

2.4

61

53

.17

0.3

51

.04

3.0

64

.60

2.3

05

.74

3.4

42

.30

0.3

30

.50

PR

TW

.09

(b)

42

04

4.4

28

3.0

01

63

.60

2.8

12

.00

16

0.7

90

.35

1.0

43

.06

4.6

01

.79

4.4

62

.68

1.7

90

.22

0.3

3

41

98

5.6

28

3.0

01

63

.01

2.6

03

.25

16

0.4

10

.35

1.0

43

.06

4.6

02

.00

4.9

92

.99

2.0

00

.58

0.8

8

41

88

5.4

28

3.0

01

62

.10

2.3

93

.05

15

9.7

10

.35

1.0

43

.06

4.6

02

.21

5.5

13

.31

2.2

10

.51

0.7

7

41

74

6.5

28

3.0

01

61

.10

2.3

52

.82

15

8.7

50

.35

1.0

43

.06

4.6

02

.25

5.6

13

.37

2.2

50

.44

0.6

6

41

61

72

83

.00

16

0.3

92

.84

2.6

01

57

.55

0.3

51

.04

3.0

64

.60

1.7

64

.39

2.6

31

.76

0.3

70

.56

41

50

9.5

28

3.0

01

59

.79

2.4

52

.64

15

7.3

40

.35

1.0

43

.06

4.6

02

.15

5.3

63

.22

2.1

50

.39

0.5

8

41

41

0.2

28

3.0

01

59

.48

2.8

82

.31

15

6.6

00

.35

1.0

43

.06

4.6

01

.72

4.2

92

.57

1.7

20

.30

0.4

4

41

24

9.1

28

3.0

01

57

.81

2.1

82

.72

15

5.6

30

.35

1.0

43

.06

4.6

02

.42

6.0

43

.62

2.4

20

.41

0.6

1

9.0

0

9

13

.5

13

.5 9 12

7.5 6

6.0

0

6 7.5

7.5 6 7.5

4.5

4.5

3

4.5

0

4.5 6 6 4.5

4.5 3

0.6

0.6

0.4

0.4

0.5

0.5

0.6

0.6

pa

ge

2 o

f 3

PR

TW

.09

(c)

37

56

2.7

28

3.0

01

34

.89

2.3

82

.01

13

2.5

10

.35

1.0

43

.06

4.6

02

.22

5.5

43

.32

2.2

20

.22

0.3

4

37

49

3.4

28

3.0

01

34

.55

2.0

82

.22

13

2.4

70

.35

1.0

43

.06

4.6

02

.52

6.2

93

.77

2.5

20

.27

0.4

1

37

40

32

83

.00

13

4.3

92

.16

1.5

01

32

.23

0.3

51

.04

3.0

64

.60

2.4

46

.09

3.6

52

.44

0.1

20

.19

37

29

2.2

28

3.0

01

34

.26

2.3

01

.01

13

1.9

60

.35

1.0

43

.06

4.6

02

.30

5.7

43

.44

2.3

00

.06

0.0

8

37

18

6.9

53

1.0

01

33

.95

2.3

71

.98

13

1.5

80

.35

1.0

43

.78

5.6

73

.30

8.2

54

.95

3.3

00

.22

0.3

3

37

10

3.6

53

1.0

01

33

.45

1.8

82

.82

13

1.5

70

.35

1.0

43

.78

5.6

73

.79

9.4

75

.68

3.7

90

.44

0.6

6

37

05

6.4

53

1.0

01

33

.48

2.1

81

.51

13

1.3

00

.35

1.0

43

.78

5.6

73

.49

8.7

25

.23

3.4

90

.13

0.1

9

36

91

8.4

53

1.0

01

32

.91

2.2

12

.48

13

0.7

00

.35

1.0

43

.78

5.6

73

.46

8.6

55

.19

3.4

60

.34

0.5

1

36

82

75

31

.00

13

2.6

82

.39

1.8

81

30

.29

0.3

51

.04

3.7

85

.67

3.2

88

.20

4.9

23

.28

0.2

00

.29

36

69

3.6

53

1.0

01

32

.37

2.3

01

.75

13

0.0

70

.35

1.0

43

.78

5.6

73

.37

8.4

25

.05

3.3

70

.17

0.2

5

36

63

1.6

53

1.0

01

32

.05

2.2

92

.16

12

9.7

60

.35

1.0

43

.78

5.6

73

.38

8.4

55

.07

3.3

80

.26

0.3

9

36

60

1.2

*5

31

.00

13

2.0

02

.36

1.9

41

29

.64

0.3

51

.04

3.7

85

.67

3.3

18

.27

4.9

63

.31

0.2

10

.31

PR

TW

.09

(d)

35

87

8.2

53

1.0

01

29

.79

2.2

41

.90

12

7.5

50

.35

1.0

43

.78

5.6

73

.43

8.5

75

.14

3.4

30

.20

0.3

0

35

84

5.8

*5

31

.00

12

9.6

82

.25

2.0

21

27

.43

0.3

51

.04

3.7

85

.67

3.4

28

.55

5.1

33

.42

0.2

30

.34

PR

TW

.10

38

43

05

45

.00

14

0.2

82

.65

2.3

71

37

.63

0.3

51

.04

3.8

15

.72

3.0

77

.67

4.6

03

.07

0.3

10

.47

38

32

0.5

54

5.0

01

39

.77

2.9

22

.88

13

6.8

50

.35

1.0

43

.81

5.7

22

.80

6.9

94

.20

2.8

00

.46

0.6

9

38

27

0.3

54

5.0

01

39

.53

3.0

32

.79

13

6.5

00

.35

1.0

43

.81

5.7

22

.69

6.7

24

.03

2.6

90

.43

0.6

5

38

19

5.9

54

5.0

01

39

.42

3.1

12

.78

13

6.3

10

.35

1.0

43

.81

5.7

22

.61

6.5

23

.91

2.6

10

.43

0.6

4

PR

TW

.11

39

85

2.6

54

5.0

01

49

.14

3.1

03

.01

14

6.0

40

.35

1.0

43

.81

5.7

22

.62

6.5

43

.93

2.6

20

.50

0.7

5

39

74

15

45

.00

14

8.0

82

.98

3.0

61

45

.10

0.3

51

.04

3.8

15

.72

2.7

46

.84

4.1

12

.74

0.5

20

.78

39

62

1.6

54

5.0

01

47

.61

2.3

23

.17

14

5.2

90

.35

1.0

43

.81

5.7

23

.40

8.4

95

.10

3.4

00

.56

0.8

3

39

48

4.1

54

5.0

01

46

.44

2.6

43

.41

14

3.8

00

.35

1.0

43

.81

5.7

23

.08

7.6

94

.62

3.0

80

.64

0.9

7

39

41

0.7

54

5.0

01

45

.88

2.6

32

.82

14

3.2

50

.35

1.0

43

.81

5.7

23

.09

7.7

24

.63

3.0

90

.44

0.6

6

39

28

0.9

54

5.0

01

44

.93

2.2

62

.89

14

2.6

70

.35

1.0

43

.81

5.7

23

.46

8.6

45

.19

3.4

60

.46

0.6

9

39

20

6.3

54

5.0

01

44

.65

2.5

02

.51

14

2.1

50

.35

1.0

43

.81

5.7

23

.22

8.0

44

.83

3.2

20

.35

0.5

2

PR

TW

.12

(L/B

)

31

77

2.1

*5

31

.00

11

8.4

32

.19

2.5

01

16

.24

0.3

51

.04

3.7

85

.67

3.4

88

.70

5.2

23

.48

0.3

50

.52

31

64

3.3

53

1.0

01

17

.90

1.9

52

.58

11

5.9

50

.35

1.0

43

.78

5.6

73

.72

9.3

05

.58

3.7

20

.37

0.5

5

31

50

4.9

53

1.0

01

17

.48

2.1

51

.53

11

5.3

30

.35

1.0

43

.78

5.6

73

.52

8.8

05

.28

3.5

20

.13

0.1

9

31

38

05

31

.00

11

7.0

92

.28

2.0

31

14

.81

0.3

51

.04

3.7

85

.67

3.3

98

.47

5.0

83

.39

0.2

30

.34

PR

TW

.12

(R/B

)

31

04

3.1

*5

31

.00

11

6.0

11

.94

1.6

71

14

.07

0.3

51

.04

3.7

85

.67

3.7

39

.32

5.5

93

.73

0.1

50

.23

30

89

1.1

53

1.0

01

15

.59

2.1

61

.32

11

3.4

30

.35

1.0

43

.78

5.6

73

.51

8.7

75

.26

3.5

10

.10

0.1

4

30

66

7.1

53

1.0

01

14

.84

2.2

92

.00

11

2.5

50

.35

1.0

43

.78

5.6

73

.38

8.4

55

.07

3.3

80

.22

0.3

3

30

63

4.3

*5

31

.00

11

4.7

42

.24

1.8

51

12

.50

0.3

51

.04

3.7

85

.67

3.4

38

.57

5.1

43

.43

0.1

90

.28

PR

TW

.13

(R/B

)

32

44

2.4

54

5.0

01

16

.41

2.7

32

.47

11

3.6

80

.35

1.0

43

.81

5.7

22

.99

7.4

74

.48

2.9

90

.34

0.5

1

32

34

2.3

54

5.0

01

16

.15

2.9

52

.22

11

3.2

00

.35

1.0

43

.81

5.7

22

.77

6.9

24

.15

2.7

70

.27

0.4

1

32

19

0.3

54

5.0

01

15

.66

2.6

52

.61

11

3.0

10

.35

1.0

43

.81

5.7

23

.07

7.6

74

.60

3.0

70

.38

0.5

7

32

07

05

45

.00

11

5.2

92

.76

2.1

41

12

.53

0.3

51

.04

3.8

15

.72

2.9

67

.39

4.4

42

.96

0.2

50

.38

PR

TW

.13

(L/B

)

32

44

2.4

54

5.0

01

16

.41

2.7

32

.47

11

3.6

80

.35

1.0

43

.81

5.7

22

.99

7.4

74

.48

2.9

90

.34

0.5

1

32

34

2.3

54

5.0

01

16

.15

2.9

52

.22

11

3.2

00

.35

1.0

43

.81

5.7

22

.77

6.9

24

.15

2.7

70

.27

0.4

1

9 9 7.5 9 9 9 7.5

7.5

6 6 4.56 6

4.5

4.5

4.5 6

4.5

4.5 3

4.5

3

0.5

0.4

3 4.5

0.5

0.6

0.8

0.5

0.4

0.5

pa

ge

3 o

f 3



B.4 Existing channel drainage design

GOVERNMENT OF NEPAL






NEP)

Mawa Ratuwa Basin

1 Introduction

The following outlines the drainage design for the locations identified as requiring culvert

structures to convey existing channel flows through the proposed embankments into the main

river.

2 Runoff calculation

Catchment area contributing the runoff on country side of embankment at structure : PRTW.04

of Mawa river is 6 hectare. This is an assumption based on reviewing aerial imagery and maps

of the area. The 50 year return periods and 10 year return periods have been analysed. During

the 50 year return period, the High Flood Level in the river will prevent flows from passing

through the culvert into the river, however the calculation is undertaken to give an appreciation

of the maximum culvert size required. The 10 year return period is analysed as a more

reasonable design event.

The total discharge(Q) using rational method is given by:

Q =CiA/36

Where, Q = flow in cumecs

C = runoff coefficient, i.e. ratio between runoff and rainfall.

I = rainfall in cm per hour and

A = drainage area contributing to runoff in hectare.

Here, C = 0.50, for cultivated lands with average infiltration rate of loams and similar soil.

i = rainfall in cm per hour (2.25 mm/min for 50 year return period and 1.73mm/min for

the 10 year return period. Reference : Journal of Hydrology and Meterology, Vol.3,

No.1, 2006 By P.C.Jha. Location: Damak.)

i =2.25*60 = 135.0 mm/hr =13.50 cm/hr for 50 year return period

i =1.73*60 = 103.8 mm/hr = 10.38 cm/hr for 10 year return period

A = drainage area contributing runoff = 6 hectare

Hence Q = 0.50*13.50*6/36 = 1.125 cumecs for 50 year return period

Q = 0.50*10.38*6/36 = 0.87 cumecs for 10 year return period

As the catchment is flat and the runoff is in sheet flow it is proposed to pass the runoff through

four outlets located at four different appropriate locations.



Hence discharge through each outlet = 1.125/2 = 0.56 cumecs for 50 year return period

discharge through each outlet = 0.87/2 = 0.43 cumecs for 10 year return period

3 Design of Concrete Pipe outlet

It was chosen to use pre-cast circular concrete pipes to form the culvert, due to availability and

ease of construction.

The velocity should be kept low in order to reduce the scour risk at the outlet. However, a balance

must be made with pipe size, as smaller pipes will be cheaper and reduce the impact of flooding

from backflows from the main river if the flap valve gets stuck in the open position.

During the 1 in 50 year event there will be no gravity flow through the conduit due to high flood

level in the river. On balance, the 1 in 10 year rainfall event has been used for design.

It has been proposed to lay the culverts at 1 in 100 slope.

Based on the flowrate of 0.43 cumecs and 1 in 100 slope, the following concrete pipe chart in

Figure 34 based on the Colebrook White formula for pipe flowing full was used which showed the

required pipe diameter is around 525mm, with velocities of approximately 1.6m/s.

It is proposed to round up pipe diameter to account for siltation/blockage over the lifetime, and

for the potential for increased rainfall/runoff amounts than calculated. In the Terai region, it is

understood that 600mm diameter pipe lines are readily available. Therefore the proposal is for

600mm diameter pipes to be used.



Figure 34: Pipe selection chart based on Colebrook White formula for pipe full. Greenannotations are the inputs, purple annotations show the results

Source: Pipe chart from Hydraulic Design; Condron Concrete works. Accessed online:[http://condronconcrete.ie/concrete/hydraulic-design/]



B.5 Toe drain design

GOVERNMENT OF NEPAL






NEP)

Mawa Ratuwa Basin

1 Introduction

The following outlines the toe drain design, and for the culverts to convey the flows from the toe

drain through the proposed embankments into the main river.

2 Runoff calculation

The toe drains will contain seepage flows and direct rainfall on to the embankment faces. As the

seepage will only occur in high flood events, the direct rainfall has been used for the purposes

of sizing. The 50 year return periods and 10 year return periods have been analysed. During the

50 year return period, the High Flood Level in the river will prevent flows from passing through

the culvert into the river, however the calculation is undertaken to give an appreciation of the

maximum culvert size required. The 10 year return period is analysed as a more reasonable

design event.

In order to be conservative, the area of embankment face has been based on the maximum height

embankment across the two detailed design packages; 6m in Mohana Khutiya.

Embankment length = taken as 1000m

Embankment height = 6m

Embankment slope width = 6m * slope = 6*2 = 12m

Embankment slope drainage area = embankment length * slope width = 12,000m2

The total discharge(Q) using rational method is given by:

Q =CiA/36

Where, Q = flow in cumecs

C = runoff coefficient, i.e. ratio between runoff and rainfall.

I = rainfall in cm per hour and

A = drainage area contributing to runoff in hectare.

Here, C = 0.50, for cultivated lands with average infiltration rate of loams and similar soil.

i = rainfall in cm per hour (2.25 mm/min for 50 year return period and 1.35mm/min for

the 10 year return period. Reference : Journal of Hydrology and Meterology, Vol.3,

No.1, 2006 By P.C.Jha. Location: Damak.)





A = drainage area contributing runoff = 1.2 hectare

Hence Q = 0.50*13.5*1.2/36 = 0.23 cumecs for 50 year return period

Q = 0.50*10.38*1.2/36 = 0.17 cumecs for 10 year return period

3 Design of Concrete Pipe outlet

It was chosen to use pre-cast circular concrete pipes to form the culvert, due to availability and

ease of construction.

The velocity should be kept low in order to reduce the scour risk at the outlet. However, a balance

must be made with pipe size, as smaller pipes will be cheaper and reduce the impact of flooding

from backflows from the main river if the flap valve gets stuck in the open position.

During the 1 in 50 year event there will be no gravity flow through the conduit due to high flood

level in the river. On balance, the 1 in 10 year rainfall event has been used for design.

It has been proposed to lay the culverts at 1 in 100 slope.

Based on the flowrate of 0.17 cumecs and 1 in 100 slope, the following concrete pipe chart in

Figure 34 based on the Colebrook White formula for pipe flowing full was used which showed the

required pipe diameter is around 375mm, with velocities of approximately 1.7m/s.

It is proposed to round up pipe diameter to account for some siltation/blockage over the lifetime,

and for the potential for increased rainfall/runoff amounts than calculated. In the Terai region, it

is understood that 600mm diameter pipe lines are readily available. Therefore the proposal is for

600mm diameter pipes to be used. This will also ensure a consistent design with the culverts

installed for the existing channels (see Appendix B.4).

4 Design of toe drain channel

It is proposed to use an open channel drain along the toe. A perforated pipe option was discussed

but the maintenance requirements if the pipe becomes blocked are more onerous than clearing

an open channel.

A Mannings calculation was undertaken using the following formula:

Where:

Q is as above

K = 1

n = 0.036 based on worst case value in the range given for ‘gravel bottom with sides of dry rubble

or riprap’ as per Chow 1979

A = area of trapezoidal channel, based on side slopes of 1 in 2 and base width of 0.25m

P = wetted perimeter based on trapezoidal channel as above

S = 1 in 500; slopes of the embankment toe may vary locally but this was selected as a

representative value



The iterative calculation found that a water depth of 0.35m gives a flowrate of 0.133m3/s.

Compared to the required flowrate calculated above, this was deemed acceptable considering

the varying slopes and that some flow will also occur within the rip rap base.

Figure 35: Pipe selection chart based on Colebrook White formula for pipe full. Greenannotations are the inputs, purple annotations show the results

Source: Pipe chart from Hydraulic Design; Condron Concrete works. Accessed online:[http://condronconcrete.ie/concrete/hydraulic-design/]



D. Design drawings

D.1 Location priority works

Note this includes embankments that were removed from the package (PRTW.06 L/B and R/B).



D.2 DED Drawings

In the following pages the DED drawings, A3-size, are provided.

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALESIGNATUREGOVERNMENT OF NEPAL

MINISTRY OF ENERGY, WATER RESOURCES

AND IRRIGATION

DEPARTMENT OF WATER RESOURCES

AND IRRIGATION

Water Resources Project Preparatory FacilityJawalakhel, Lalitpur

DATE:

27/09/19

DWG NO:Project: Preparation of Priority River

Basin Flood Risk Management Project

(ADB GRANT NO:0299-NEP)

Sub-Project:Mawa Ratuwa Basin

Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH

TOTAL MANAGEMENT SERVICES (TMS)

SHEET NO:

REVISION: 3

MR_DS

Notes: All levels and measurements are in meters unless indicated differently. All levels refer to meters above sea level (masl). HFL=High Flood Level

01

SCHEDULE OF DRAWINGS

DescriptionDWG NoTitle Sheets

PRTW.01a

PRTW.01b

PRTW.02

PRTW.03

PRTW.04

PRTW.05a

PRTW.05b

MR_OV OverviewMR_OV_1a

MR.001a

MR_LP_001a

MR_OV_1b

MR.001b

MR_LP_001bMR_OV_02

MR.002

MR_LP_002

MR_OV_03

MR.003

MR_LP_003

MR_OV_04

MR.004

MR_LP_004MR_OV_05a

MR.005a

MR_LP_005aMR_OV_05b

MR.005b

MR_LP_005b

Overview

Typical Crosssection of embankment with

Revetment

Typical Spur section

Longitudinal Profile

Overview

Overview

Overview

Overview

Overview

Overview


Revetment(1)


Revetment(2)


Revetment(3)








Revetment(1)


Revetment(2)

Typical Crosssection of embankment with Revetment



Revetment(1)


Revetment(2)


Revetment(3)

Typical Crosssection of Revetment


Revetment







1

1

1

1

1

1

1

1

1

2

1

2

3

5

1-31

Typical Crosssection of embankment with Revetment(4)

4

2

3

1-21

2

1

1

2

3

4

1-21

2

3

11

21

PRTW.10

PRTW.11

MR_OV_10 Overview

MR.010

MR_LP_010

MR_OV_11

MR.011

MR_LP_011



Overview

Typical Crosssection of Revetment


Revetment(1)

Typical Crosssection of embankment with Revetment(2)


1

1

3

1

2

3

1-2

4

1


Revetment(1)


Revetment(2)

1

2


DWG NoTitle Sheets

PRTW.07

PRTW.08

PRTW.09a

PRTW.09c

PRTW.09d

MR_OV_07

MR.007

MR_LP_007

MR_OV_08

MR.008

MR_LP_008

MR_OV_09a

MR.009a

MR_LP_009a

MR.009d

MR_LP_009d

Overview

Overview

Overview






Revetment(1)


Revetment(2)




Revetment







1

1

1

1

1

2

3

1-21

2

1

1-3

2

1

1-2

21

PRTW.09b

MR_OV_09b

MR.009b

MR_LP_009b

Overview



Revetment


1

1

2

1-2MR_OV_09c

MR.009c

MR_LP_009c

OverviewTypical Crosssection of embankment with

Revetment(1)


Revetment(2)


Revetment(3)

1

2

3

4

1

MR_OV_09d Overview1

Description


-

MR_LP 1 Location PlanLocation Plan

MR_NS_001Notes sheet 1 Notes

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION


DATE:

27/09/19





Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION: 3

MR_DS


02


MR_PC_1 Typical Crosssection of Pipe culvert (Type I)

DWG NoTitle Sheets

PRTW.12LB

PRTW.13LB

MR_OV_12LB

MR.012LB

MR_LP_012LB

Overview




Revetment(1)


Revetment(2)



1

1

2

3

1

1

MR_OV_13LB

MR.013LB

MR_LP_013LB

Overview


Revetment(1)


Revetment(2)

1

2

3

1

PRTW.12RB

MR_OV_12RB

MR.012RB

MR_LP_012RB

Overview



Revetment(1)


Revetment(2)


1

1

2

3

1

PRTW.13RB

MR_OV_13RB

MR.013RB

MR_LP_013RB

Overview



Revetment


1

1

2

1

Description


1-2

MR_PC_2 1 Typical Crosssection of Pipe culvert (Type II)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

MR_PC_3 Typical Crosssection of Pipe culvert (Type III) 1-2

PIPE

CULVERTS

BK

KPS

CE

AC

MR_DT_01 Typical Tie in details 1TIE IN

DETAILS

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE

NOTES

GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION: 3

DWG NO:

1/2

Notes_001

Drawing Notes:

1. All dimensions and levels in this drawing set are shown in meter.

2. Refer to Topographical Survey Report, December 2018 for locations and co-ordinates of the bench marks used for this works package. The

nearest IGS station used for this survey is Lhasa, China (Longitude 910 06' 14.510073”E, Latitude 290 39' 26.40090”N, Ellipsoidal Height3624.612m). All drawings are in WGS 84 North 44R coordinate system.

3. The Contractor shall verify the alignment (depending on post monsoon dynamic movement of the bank) dimensions and levels of all structures

stated in this drawing for correctness prior to establishing the works setting-out points.

4. Ground Investigation (GI) shall be undertaken prior to the construction works. The GI Specifications are given in Paragraph 8.2 of Section 6:

Employer's Requirements. The Employer and the Engineer shall be informed if the soil parameters obtained from the GI varies from the assumed

parameters stated in the Detailed Engineering Report for the package.

5. Embankment fill material shall be

· Class 1A - well graded granular material for embankment general fill, or

· Class 2A or 2B - wet or dry cohesive material for embankment general fill, and

· Class 6G - selected granular material for embankment toe drainage and gabion stone

· Type 1 - unbound mixture for the gravel access road on top of the embankment. Gravel is defined as aggregate derived from a natural,

unconsolidated, coarse-grained sedimentary deposit consisting water worn rock fragments.

i) Material Grading:

Particle size distribution for Class 1A well graded granular material), Class 6G (selected granular material for embankment toe drainage)

and Type 1 unbound mixture for the gravel access road shall comply with the following standard gradings:

Particle

(Sieve) Size

Percentage by Mass Passing the Sieve

Class 1A -

granular

material for

General Fill for

embankment

Class 2A or 2B -

wet or dry

cohesive

material for

embankment

general fill

Class 6G - Rock

Fill for

embankment

toe drainage

and Gabion

Stone forrevetment

Type 1 material

for gravel

access road on

top of

embankment

200 mm 100% 98-100%

180 mm - 80 - 100%

125 mm 95 - 100% 100%

90 mm 0 - 20%

63 mm 100

45 mm 0 - 5%

31.5 mm 75 - 99

16 mm 43 - 81

8 mm 23 - 66

4 mm 12 - 53

2 mm 6 - 42

1 mm 3 - 32

63 micron <15% 15 - 80% 0 - 9

-

- -

-

-

--

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

ii) For Class 1A Embankment General Fill Material, the uniformity coefficient, i.e. the ratio of the particle diameters D60 to D10 on theparticle-size distribution curve shall be 10 (minimum).

D60 = particle diameter at which 60% of the soil by weight is finerD10 = particle diameter at which 10% of the soil by weight is finer

For Class 6G Rock Fill for embankment toe drainage and Gabion stone shall be durable rock of minimum density 2400kg/cu.m. The grading

of the material shall be such that the minimum particle size shall exceed the maximum size of the gabion mesh opening, and a maximum

particle size of 200mm.

For Class 6G rock fill and gabion stone materials, D15 = 100mm;

D50 = 150 mm; and

D100 = 200 mm.

The properties of Type 1 aggregates used for the gravel road mixture shall be in accordance with BS EN 13242.

i) Compaction:

The Contractor may use one of the following plant and equipment for compacting embankment fill material. The minimum number of passes,

N and the maximum depth of the compacted layer, D as stated in the following table shall be adopted depending on the Contractor's

preferred method of compaction plant. The minimum number of passes, N is the minimum number of times that each point on the surface

of the layer being compacted shall be traversed by the item of compaction plant in its operating mode or struck by power rammers or falling

weight compactors. D is the maximum depth of the compacted layer.

Type ofCompaction Plant

Category Ref. D N

Smoothedwheeled roller (orvibratory rolleroperating withoutvibration)

Mass per meter width of roll:

over 2100 kg up to 2700 kg


over 5400 kg

1

2

3

125

125

50

8

6

4

Grid Roller

Deadweight tamping

roller

Pneumatic-tyred

roller

Vibratory tamping

roller

Vibratory roller



over 8000 kg



over 6000 kg

Mass per wheel:






over 12000 kg

Mass per meter width of a vibrating

roll:








over 5000 kg

Mass per unit width of vibratory roll:










over 5000 kg

1

2

125

150

12

12

1

2

150

200

12

12

12

125125

1210

3 125 104 150 85 150 86 175 6

1

2

125125

1210

3125 10

4150 8

5150 8

6

175 6

7

8

175 6

175 6

175 6

175 122125 103150 84150 45125612571258125912510

75 16

44444

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

Project: Preparation of Priority River



Sub-Project: Mawa Ratuwa Basin

Type ofCompaction Plant

Category Ref. D N

Vibrating plate orcompactor

Mass per m2 of base plate:

over 1100 kg and up to 1200 kg




over 2100 kg

Vibro-tamper

Power rammer

Dropping-weightcompactor

Mass:




over 100 kg

Mass:

100 kg up to 500 kg

over 500 kg

Mass of rammer over 500 kg weight

drop:over 1m up to 2mover 2m

175 62125 63150 54150 35

75 10

1125215032254

100 3

333

12752

150 6

12

12752

150 6

12

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE

NOTES

GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION: 3

DWG NO:

2/2

Notes_001

6. Geotextiles shall be non-woven fabric made of 100% polypropylene continuous fibre, spun-bonded with the exclusion of glues or welds.

Material shall comply with the following requirements:

· Minimum tensile strength = 9.5 KN/m;

· Minimum trapezoidal tear = 225 N;

· Minimum vertical water flow 50 mm head = 110 mm/s; and

· Minimum apparent opening size (AOS) = 0.27 mm.

7. Gabion requirements include:

· Gabions and mattresses shall consist machine woven rectangular units made from double twisted hexagonal mesh of heavy galvanised ad

zinc coated mild steel wire average strength of 380N/mm2.

· Each row of gabions shall be wired to the adjoining row at the top and bottom edges and at the corners. The end panels in Box gabions

should be mechanically connected with the main body at the manufacturing site by selvedging both to a common selvedge wire.

· Each gabion shall be carefully packed by hand with stone so placed as to minimize voids. The Top layers of stones shall be placed with their

flattest sides uppermost to provide a smooth surface for placing the lid. The gabions shall be filled 25 mm above the top so that the lid can

be tightly stretched over the stone. The lid shall be wired all round.

8. DWRI to provide Cadastral mapping to the Contractor; site boundaries, compound locations and access routes to be agreed by DWRI and the

Contractor prior to construction.

9. Plan drawings show simplified embankment footprints; embankment widths will vary locally based on undulating existing ground levels.

10. DWRI and the Contractor to consult with the Department of Roads and relevant local authority regarding embankments which connect to

existing bridges or roads (as marked on the drawings).

11. The proposed embankments for the priority works were designed for 1 in 50 year flood protection. Embankments to tie in upstream and

downstream to high ground or structures which are at minimum at High Flood Level (HFL). Proposed length of tie-ins to be confirmed on site by

The Contractor and altered as required with consultation and approval of the Engineer. The crest level of the priority work embankments shall

continue in this direction to the nearest high ground which is at crest level (HFL + freeboard) in a separate follow-on project in order to ensure

the full benefits of the proposed flood defence

12. Position of toe drain and proposed culverts have been selected at this stage based on low spots identified in the topographic survey l-profiles;

these locations may no longer be appropriate based on topographic changes following monsoon rains since original survey. All locations of toe

drain and proposed culverts to be confirmed on site by the Contractor and altered as required with consultation and approval of the Engineer. All

toe drain culverts shall be Type III as indicated in the drawings.

13. Health and Safety risks identified by the Engineer are described in the Designer's Hazard Elimination Management Record in the DED report.

Contractor to undertake their own assessment and develop appropriate Safe Systems of Working to be approved by DWRI. The key construction

risks are as follows;

· Identification of existing overhead and underground services

· Working within and adjacent to water and during flood

· Heavy lifting of precast concrete elements

· Excavation of channel bed during works

· Pollution to the river

Key maintenance risks:

· Embankment shall be inspected after major earthquake events and any damage and/or displacement of materials shall be repaired

immediately to avoid further risk of breaching and embankment failure.

· Slip, trip and fall during routine inspection after every flood event.

· Operation, repair and/or replacement of inlet and outlet structures (including penstocks and flap valves) will require access from the river

side and dry working area can be provided by placing sand bags.

· Embankment defences may impound in floods greater than design flood of 1 in 50 year. During the extreme flood events the early warning

instructions shall be followed.

· Overtopping of proposed embankments causing flooding downstream, potential for embankment failure and breach wave.

14. The Section 6 - Employer's Requirements Specification document must be referred to for full requirements regarding construction.

15. The Penstock shall be manufactured in Stainless Steel. The recommended grade of stainless steel is BS EN 10088-1,2:2014 grade 316L. The

Contractor shall prepare a fabrication drawing suitable for the fabrication of all elements of steelwork. The fabrication drawing(s) shall be submitted

to the Engineer for acceptance at least two weeks prior to the planned date for fabrication.

16. The Flap Gate shall be manufactured in Stainless Steel. The recommended grade of stainless steel is BS EN 10088-1,2:2014 grade 316L. The

Contractor shall prepare a fabrication drawing suitable for the fabrication of all elements of steelwork. The fabrication drawing(s) shall be submitted

to the Engineer for acceptance at least two weeks prior to the planned date for fabrication.

17. Trash Screens shall be fabricated from mild steel sections, galvanised to BS EN ISO 1461:2009. The screen bars are to be from 100mm x 10mm flat

with the thickness as indicated on drawing. Welding shall be carried out in accordance with BS EN 1011. The Contractor shall prepare a fabrication

drawing suitable for the fabrication of all elements of steelwork. The fabrication drawing(s) shall be submitted to the Engineer for acceptance at least

two weeks prior to the planned date for fabrication.

18. Grass seeding of slopes and vetiver grass planting to be undertaken to ensure robust grass cover. Planting shall comply with Clause 15 of Section

6 - Employer's Requirements.

19. Reinforced concrete inlet and outlet structures shall comply with Clause 16 and pre-cast concrete pipes shall comply with Clause 17 of Section 6 -

Employer's Requirements.

20. Additional access ramps (1 in 10 slope) between the country side and the riverside shall be provided where required after consultation with localcommunity groups.

21. Position of toe drain and proposed culverts have been selected at this stage based on low spots identified in the topographic survey l-profiles;

these locations may no longer be appropriate based on topographic changes following monsoon rains since original survey. All locations of toe drain

and proposed culverts to be confirmed on site by the Contractor and altered as required with consultation and approval of the Engineer. All toe drain

culverts shall be Type III as indicated in the drawings.

Embankment height <2m 2-3m 3-4m 5-6m 6m

Drain height None 1m 1.33m 1.67m 2m

22. Highly permeable soils below the base of the flood embankment shall be removed and filled with embankment material to achieve sufficient cut

off during flooding.





BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION


DATE:

27/09/19





Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_LP

3


01

LOCATION PLAN

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

Nepal india border

Location works See overview (Dwg No:MR_OV)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION


Drawing TitleProject: Preparation of Priority River




MOTT MACDONALD

IN ASSOCIATION WITH

TOTAL MANAGEMENT SERVICES

(TMS)

SHEET NO: 1

DWG NO:

Overview

MR_OV

1:150000BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3DATE:

27/09/19

BK

KPS

CE

AC

A3

PRTW-01aSpur

Embankment Revetment

No. of Spurs:

Spur Dimension

Chainage Start End Length

Embankment

Revetment

Spurs

(Type 1)0+030m 0+280m 250m

7

45

18 7.5 3

0+000m 0+420m 420m

0+000m 0+420m 420m

Spurs

Spacing(m)

Length(m) Base Width(m) Height(m)

Co-ordinates

SOP Northing

(m)

Easting

(m)

1

2

Elevation

(masl)

564473 2936812

564616 2936507

91.92 m

91.11 m

3 564606 2936477 91.14 m

0+000m

0+420m

A

MR.001a_1

0 25

SCALE BAR 1:2000

50 100

SOP1

SOP2

SOP3

Embankment to tie in to natural ground

along tributary right bank. Proposed tie in

length of 100m to reach high ground;to

be confirmed on site. See note 11.

Proposed to discharge the toe drain into

tributary

Embankment to tie in to

existing bridge; see note 10

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview

SIGNATUREGOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_01a

3


PRTW.01a


KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

19.50

0.600.750.750.750.75

3.004.506.007.50

4.50 7.50 7.50

Downstream Upstream

SECTION B-B

Scale 1:200

Scale 1:200

0.750.750.750.750.60

30.00

18.00

SECTION A-A

Scale 1:200

12.00

Geotextile

Gabion revetmentGabion launching apron

(gabion box: 3.00 x 1.50 x 0.60m)

Gabion spur

(gabion box: 3.00 x 1.50 x 0.75m)

Embankment Top Level (Varies)

Spur Top level (Varies)

19

.50

30.00

18.00 3.0

0

4.5

0

6.0

0

7.5

0

7.5

04

.50

12.00

PLAN VIEW (TYPE -1)

Scale 1:200

Upstream

Downstream

A A

B

B

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALE :SIGNATUREGOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.01a

MR.001a

2/2

3

TYPICAL SPUR SECTION (TYPE 1)

0 6 12 18 24 30

Scale Bar : 1:200

REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

80

81

82

83

84

85

86

87

88

89

90

91

92

90

.58

8

90

.08

2

89

.57

6

89

.07

0

88

.56

4

88

.12

5

87

.68

6

CHAINAGE : 0+000.00 - 0+420.00

80

81

82

83

84

85

86

87

88

89

90

91

92

87

.48

8

88

.54

0

88

.77

8

90

.47

91

.97

89

.78

91

.28

CHAINAGE (km)

0+

00

0.0

0

0+

05

0.0

0

0+

10

0.0

0

0+

15

0.0

0

0+

20

0.0

0

0+

25

0.0

0

0+

30

0.0

0

0+

35

0.0

0

0+

40

0.0

0

0+

42

0.0

0

88

.44

48

9.7

44

91

.24

4

89

.61

49

1.1

14

EXISTINGLEVEL (masl)

EMBANKMENT

WATER LEVEL(masl)

LEVEL (masl)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)

Sub-Project:Mawa Ratuwa basin

MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:

REVISION: 3


PRTW.01a


MR_LP_01a

01

EMBANKMENT TOP LEVEL(m) MAXIMUM WATER LEVEL(m) GROUND LEVEL(m) Proposed Location of Culvert Direction of Toe Drain Slope

DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

H=1:1000

V=1:100BK

KPS

CE

AC

A3

PRTW-01bSpur


No. of Spurs:

Spur Dimension


Embankment

Revetment

Spurs

(Type 2)

0+180m 0+380m

10

45

18 7.5 3

0+000m 1+780m 1780m

0+315m 0+920m 1780m

Spurs

Spacing(m)


0+000m 0+315m

0+920m 1+780m

1+260m 1+460m400m

Co-ordinates

SOP Northing

(m)Easting

(m)

1

2

Elevation

(masl)

564656 2936498

564918 2934758

91.21 m

87.79 m

0+000m

1+780m

AMR.001b_1

BMR.001b_2

CMR.001b_3

DMR.001b_4

0 25

SCALE BAR 1:8000

50 200100 400

Access ramp to connect existing

access track to embankment.

1 in 10 slope, approximately 5m long

Proposed location of culvert

for toe-drain; see note 12

SOP1

SOP2

Embankment to tie in to natural ground.

Proposed tie in length of 100m to reach high

ground; to be confirmed on site. See note 11


existing embankment

Notable historic river movement;

alignment of embankment to be

re-confirmed by Contractor. See

note 3

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview



AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_01b

3


PRTW.01b


KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE

TYPICAL CROSS SECTION OF

EMBANKMENT WITH REVETMENT(1)

GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION






MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

1/51:100

PRTW.01b

(CH 0+145)

MR.001b


HFL(89.38)

River Side

To be excavated

Embankment Top Level(90.88

Existing ground level

2

1

3.00

Freeboard1.50

6.00

2.063.00

3.003.009.00

3.00

d=3.35

0.2

0

0.1

00.504.00

0.50

5.00

REVISION: 3

1.3

31

1

SCALE BAR

10 2 5

1:100

0.3

5

0.25

Non-woven Geotextile

(see Note 7)

Embankment fill. Refer to

note 5 for material

properties,grading and

compaction requirements.

100mm thick well

graded 5-20mm

dia granular

surface layer.

200mm thick Type 1

un-bound mixture

for gravel access

road.Refer to note 5

for material

properties, grading

and compaction

requirements.Class 6G selected granular

material for rock fill.Refer to

note 5 for material


compaction requirements

Gabion revetment filled with class 6G

selected rockfill.Refer to note 5 for material

properties,grading and compaction

requirements.Gabion dimension

3.00 x 1.50 x 0.40 m

Gabion launching appron filled with class

6G selected granular material. Refer to

note 5 for material properties,grading and

compaction requirements.Gabion

dimension 3.00 x 1.50 x 0.60 m

300mm thick sweet soil

with grass seeding and

vetiver planting

Trapezoidal toe drain;

channel sides (1V:2H) and

base constructed from

300mm thick rock fill (refer

to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

Non-woven

Geotextile (see

Note 7)

BK

KPS

CE

AC

A3

2

10.51.65

0.3

0

0.50

(23)d

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION






MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

2/51:100

PRTW.01b

(CH 0+600)

MR.001b


HFL(88.60)

River Side

Embankment Top Level(90.1)


2

1

3.00

Freeboard1.50

6.00

2.063.00

3.003.009.00

3.00

d=3.50


note 5 for material



100mm thick well

graded 5-20mm dia

granular surface

layer.

200mm thick Type 1

un-bound mixture for

gravel access

road.Refer to note 5 for

material properties,

grading and compaction

requirements.

0.2

0

0.1

00.504.00

0.50

5.00

REVISION: 3

1.3

3

1

1

SCALE BAR

10 2 5

1:100

0.3

5

0.25Class 6G selected

granular material for rock

fill. Refer to note 5 for

material properties and

grading requirements.

Non-woven Geotextile

(see Note 7)





3.00 x 1.50 x 0.40 m








vetiver planting





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

Non-woven

Geotextile (see

Note 7)

BK

KPS

CE

AC

A3

2

1

0.51.65

0.3

0

0.50

(23)d

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION






MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

3/51:100

PRTW.01b

(CH 1+450)

MR.001b


HFL(87.30)

River Side

Embankment Top Level(88.82)Existing ground level

2

1

3.00

Freeboard1.50

6.00

2.583.00

3.003.009.00

3.00


note 5 for material



100mm thick well graded

5-20mm dia granular

surface layer. 200mm thick Type 1

un-bound mixture

for gravel access


for material

properties, grading

and compaction

requirements.

0.2

0

0.1

00.504.00

0.50

5.00

REVISION: 3

SCALE BAR

10 2 5

1:100

d=

0.7

0

0.3

5

0.25

Non-woven

Geotextile (see

Note 7)





3.00 x 1.50 x 0.30 m








vetiver planting





to note 5)

Non-woven

Geotextile (see

Note 7)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

2

1

0.5

1.65

0.3

0

0.50

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION






MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

4/51:100

PRTW.01b

(CH 1+485)

MR.001b


HFL(87.30)

River Side

Embankment Top Level(88.83)Existing ground level

2

1

3.00

Freeboard1.50

6.00

2.063.00

3.003.009.00

3.00

d=0.70

Class 1A well graded

material for embankment

general fill.Refer to note for

material properties,grading

and compaction

requirements.


5-20mm dia granular

surface layer.

200mm thick Type 1


gravel access road.

Refer to note 5 for



requirements.

0.2

0

0.1

00.504.00

0.50

5.00

REVISION: 3

SCALE BAR

10 2 5

1:100

0.3

5

0.25

Non-woven

Geotextile (see

Note 7)





3.00 x 1.50 x 0.40 m








vetiver planting





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

Non-woven

Geotextile (see

Note 7)

BK

KPS

CE

AC

A3

2

1

0.5

1.65

0.3

0

0.50

Scale 1:200

22.50

0.600.750.750.750.75

3.004.506.007.50

6.00 7.50 9.00

Downstream Upstream

SECTION B-B

Scale 1:200

0.750.750.750.750.60

31.50

18.00

SECTION A-A

Scale 1:200

13.50

Geotextile

Gabion revetmentGabion launching apron

(gabion box: 3.00 x 1.50 x 0.60m)

Gabion spur

(gabion box: 3.00 x 1.50 x 0.75m)



22

.50

31.50

18.00 3.0

0

4.5

0

6.0

0

7.5

0

9.0

06

.00

13.50

PLAN VIEW (TYPE -2)

Scale 1:200

Upstream

Downstream

A A

B

B


DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.01b

MR.001b

5/5TYPICAL SPUR SECTION (TYPE 2)

0 6 12 18 24 30

Scale Bar : 1:200

3REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

80

81

82

83

84

85

86

87

88

89

90

91

92

87

.06

86

.83

1

86

.85

5

86

.87

9

86

.90

3

86

.92

7

86

.22

9

86

.51

7

CHAINAGE : 0+000.00 - 1+780.00

89

.37

6

89

.54

91

.04

88

.78

90

.28

CHAINAGE (km)

0+

00

0.0

0

0+

05

0.0

0

0+

10

0.0

0

0+

15

0.0

0

0+

20

0.0

0

0+

25

0.0

0

0+

30

0.0

0

0+

35

0.0

0

0+

40

0.0

0

0+

45

0.0

0

0+

50

0.0

0

0+

55

0.0

0

0+

60

0.0

0

89

.71

79

1.2

17

89

.13

99

0.6

39

88

.68

79

0.1

87


EMBANKMENT

WATER LEVEL(masl)

LEVEL (masl)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.01b


MR_LP_01b

01


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

86

.51

7

86

.31

2

86

.10

7

86

.74

2

88

.01

3

88

.64

9

88

.38

89

.88

0+

60

0.0

0

0+

65

0.0

0

0+

70

0.0

0

0+

75

0.0

0

0+

80

0.0

0

0+

85

0.0

0

0+

90

0.0

0

0+

95

0.0

0

1+

00

0.0

0

1+

05

0.0

0

1+

10

0.0

0

1+

15

0.0

0

1+

20

0.0

0

1+

25

0.0

0

86

.22

98

8.4

41

89

.94

1

87

.23

88

.18

48

9.6

84

88

.73

68

7.9

22

89

.42

2

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.01(b)


MR_LP_01b

02


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

80

81

82

83

84

85

86

87

88

89

90

91

92

88

.64

9

89

.28

4

88

.12

5

88

.09

9

88

.07

3

88

.04

6

88

.02

0

87

.84

89

.34

87

.62

89

.12

86

.97

88

.47

86

.35

87

.85

1+

25

0.0

0

1+

30

0.0

0

1+

35

0.0

0

1+

40

0.0

0

1+

45

0.0

0

1+

50

0.0

0

1+

55

0.0

0

1+

60

0.0

0

1+

65

0.0

0

1+

70

0.0

0

1+

75

0.0

0

17

80

.00

88

.73

68

7.9

22

89

.42

2

88

.12

87

.22

78

8.7

27

86

.28

98

7.7

89

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.01(b)


MR_LP_01b

03


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

AMR.002_1

0+825m

0+000m

B

MR.0

02_2

0 25

SCALE BAR 1:4000

50 200100

SOP1




Proposed location of

culvert for toe-drain; see note 12

SOP2

Embankment to tie in to natural

ground. Proposed tie in length of

50m to reach high ground; to be

confirmed on site. See note 11

Embankment to

tie in to existing bridge; see note 10

Notable historic river

movement; alignment of

embankment to be

re-confirmed by Contractor.

See note 3 and 23

PRTW-02Spur


No. of Spurs:

Spur Dimension


Embankment

Revetment

Spurs

(Type 3) 0+000m 0+400m

14

30

12 7.5 3

0+000m 0+825m 825m

0+210m 0+825m 825m

Spurs

Spacing(m)


0+000m 0+210m

400m

Co-ordinates

SOP Northing

(m)

Easting

(m)

1

2

Elevation

(masl)

563775 2937550

564140 2936826

93.48 m

92.35 m

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview



AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_02

3


PRTW.02


KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DATE:

27/09/19

1/3

1:100

PRTW.02

(CH 0+080)

MR.002


HFL(91.75)

River Side

To be excavated


Existing ground level2

1

3.00

2.94

Freeboard1.50

Non-woven

geotextile

(refer note 5)

3.00 1.503.007.50

d=3.05

3.00

1.50

7.50






note 5 for material



100mm thick well

graded 5-20mm dia

granular surface layer.

200mm thick Type1

un-bound mixture

for gravel access

track.Refer to note

5 for material

properties, grading

and compaction

requirements.

0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

1.6

7

1

1

SCALE BAR

10 2 5

1:100

0.3

5

0.25

Class 6G selected

granular material for

rock fill. Refer to note 5

for material properties

and grading

requirements.

Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.40 m








vetiver planting





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

NAME SCALESIGNATURE DWG NO:

2

1 0.50

1.65

0.3

0

0.50

(23)d

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DATE:

27/09/19

2/31:100

PRTW.02

(CH 0+535)

MR.002


HFL(91.22)

River Side



1

3.00

2.94

Freeboard 1.50Non-woven

geotextile

(refer note 5)

3.00

1.50

3.003.00

7.50

1.50

d=3.40To be excavated

7.50






note 5 for material




5-20mm dia granular

surface layer.

200mm thick Type1


gravel access track.Refer

to note 5 for material

properties, grading and


0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

1.3

3

1

1

SCALE BAR

10 2 5

1:100

0.3

3

0.25Class 6G selected granular

material for rock fill. Refer

to note 5 for material

properties and grading

requirements.

Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.30 m








vetiver planting300mm thick sweet soil


vetiver planting





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

NAME SCALESIGNATURE DWG NO:

2

1 0.51.65

0.3

0

0.50

(23)d

3.0

04

.50

6.0

0

7.5

04

.50

22.5010.50

19

.5012.00

PLAN VIEW (TYPE -3)

Scale 1:200

Upstream

Downstream

A

B

B

A

7.5

0

0.75 10.50

12.00 Gabion launching apron

(gabion box: 3.00m x 1.50m x 0.70m)

Gabion spur

(gabion box 3.00m x 1.50m x 0.75m

SECTION A-A

Scale 1:200

22.500.700.75

0.75

0.75

Gabion revetment

Geotextile



3.004.506.00

4.50 7.50 7.50

SECTION B-B

Scale 1:200

Downstream Upstream

7.50

0.750.75

0.750.75

0.70

19.50

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.02

MR.002


0 6 12 18 24 30

Scale Bar : 1:200

3REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

85

86

87

88

89

90

91

92

90

.56

6

90

.47

3

90

.38

0

90

.28

6

90

.19

3

90

.03

1

89

.86

9

89

.70

7

89

.54

5

89

.38

3

89

.49

6

89

.60

9

89

.73

2

89

.83

4

89

.94

7

CHAINAGE : 0+000.00 - 0+825.00

93

94

95

91

.98

93

.48

91

.61

93

.11

91

.51

93

.01

91

.12

92

.62

CHAINAGE (km)

0+

00

0.0

0

0+

05

0.0

0

0+

10

0.0

0

0+

15

0.0

0

0+

20

0.0

0

0+

25

0.0

0

0+

30

0.0

0

0+

35

0.0

0

0+

40

0.0

0

0+

45

0.0

0

0+

50

0.0

0

0+

55

0.0

0

0+

60

0.0

0

91

.54

89

3.0

48

91

.26

69

2.7

66


EMBANKMENT

WATER LEVEL(masl)

LEVEL (masl)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.02


MR_LP_02

01


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

85

86

87

88

89

90

91

92

89

.48

4

89

.02

1

88

.55

8

88

.60

4

88

.65

0

93

94

95

91

92

.5

0+

65

0.0

0

0+

70

0.0

0

0+

75

0.0

0

0+

80

0.0

0

0+

82

5.0

09

0.8

49

93

.34

9

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.02


MR_LP_02

02


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

PRTW-03Spur


No. of Spurs:

Spur Dimension


Embankment

Revetment

Spurs

(Type 4)0+000m 0+230m

9

30

12 6 2.25

0+000m 0+535m 535m

535m

Spurs

Spacing(m)


0+000m 0+535m

230m

Inlet 0+260m

Co-ordinates

SOP Northing

(m)

Easting

(m)

1

2

Elevation

(masl)

567936 2957972

567990 2957440

195.49 m

188.55 m

0+000m

0+535m

0+260m

AMR.003_1

0 25

SCALE BAR 1:2500

50 200100





for toe-drain; see note 12

Proposed location of culvert (Type

1) for existing channel/drainage

SOP1

SOP2

Embankment to tie in to natural ground.

Proposed tie in length of 100m to reach high

ground; to be confirmed on site. See note 11

Embankment to tie in

to existing embankment

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview



AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_03

3


PRTW.03

01

1:2500BEEZAN KHADKA

KRISHNA P. SUBEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE


EMBANKMENT WITH REVETMENT

GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

1/21:100

PRTW.03

(CH 0+280)

MR.003


HFL(190.84)

River Side



1

3.00

Freeboard1.00

Non-woven

geotextile

(refer note5)

3.00 3.00

6.00

3.00

6.00

d=1.50

2.21





Class 1A well graded material

for embankment general fill.

Refer to note 5 for material



100mm thick well

graded 5-20mm dia

granular surface

layer.200mm thick Type1


gravel access

track.Refer to note 5 for



requirements.

0.2

0

0.1

00.504.00

0.50

5.00

REVISION: 3

SCALE BAR

10 2 5

1:100

0.3

5

0.25Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.50 m








vetiver planting





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

2

1

0.5

1.65

0.3

0

0.50

16.50

0.800.750.750.75

3.004.506.00

4.50 6.00 6.00

SECTION B-B Scale 1:200

Downstream Upstream

22.50

10.50

12.00

Gabion launching apron

(gabion box: 3.00 x 1.5 x 0.80m)

SECTION A-A Scale 1:200

Gabion

revetment

Geotextile

Gabion spur

(gabion box: 3.00 x 1.5 x 0.75m)

0.750.750.750.80



3.0

04

.50

6.0

0

6.0

04

.50

22.5010.50

16

.50

12.00

PLAN VIEW (TYPE -4)

Scale 1:200

Upstream

Downstream

A

B

B

A

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.03

MR.003


0 6 12 18 24 30

Scale Bar : 1:200

3REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

185

186

187

188

189

190

191

192

193

194

195

185

186

187

188

189

190

191

192

193

194

195


19

3.2

35

19

3.1

14

19

2.9

92

19

2.8

71

19

2.7

49

19

2.6

28

19

2.3

90

19

2.1

37

19

1.9

49

19

1.7

28

19

1.2

66

19

0.8

89

19

0.6

26

19

0.5

49

19

0.4

04

19

0.1

49

19

0.0

39

18

9.7

58

18

9.5

66

18

9.3

82

18

9.1

86

18

8.7

98

18

8.4

24

18

8.1

84

18

7.8

69

18

7.6

30

18

8.2

03

18

7.5

3

CHAINAGE : 0+000.00 - 0+536.31

EMBANKMENT

WATER LEVEL(masl)

196

197

196

1971

94

.23

19

5.2

3

19

2.8

41

93

.84

19

1.5

41

92

.54

18

9.7

41

90

.74

18

8.7

41

89

.74

CHAINAGE (km)

0+

00

0.0

0

0+

05

0.0

0

0+

10

0.0

0

0+

15

0.0

0

0+

20

0.0

0

0+

25

0.0

0

0+

30

0.0

0

0+

35

0.0

0

0+

40

0.0

0

0+

45

0.0

0

0+

50

0.0

0

0+

53

6.3

1

19

4.4

85

19

5.4

85

19

0.5

87

19

1.1

47

19

2.1

47

18

7.5

71

88

.57

0+

26

0.0

0

LEVEL (masl)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:

REVISION: 3


PRTW.03


MR_LP_03

01H=1:1000

V=1:100


DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

PRTW-04Spur


No. of Spurs:

Spur Dimension


Embankment

Revetment

Spurs

(Type 5)

0+000m 0+120m

15

30

12 7.5 3

0+000m 1+785m 1785m

Spurs

Spacing(m)


385m0+520m 0+785m

0+280m 0+600m 1785m

0+000m 0+280m

0+600m 1+785m

Intlet 0+014m

Co-ordinates

SOP Northing

(m)

Easting

(m)

1

2

Elevation

(m)

563708 2948376

563813 2947653

120.45 m

118.62 m

3 563864 2947625 118.42 m

8.92060+000m

0+785m

0+014m

AMR.004_1

BMR.004_2

CMR.004_3

0 25

SCALE BAR 1:4000

50 200100

SOP1


culvert for toe-drain;

see note 12


for existing channel/drainage

SOP2

SOP3


existing embankment


existing embankment

Notable historic river movement; alignment of

embankment to be re-confirmed by Contractor.

See note 3 and 23

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview



AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_04

3


PRTW.04

01

1:4000BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

1/41:100

PRTW.04

(CH 0+170)

MR.004


HFL(118.51)

River Side



1

2.85

Freeboard 1.50

Non-woven

geotextile

(refer note 5)

4.503.00 1.50

7.50

3.00

3.00

1.50

To be excavated





Embankment fill.

Refer to note 5 for

material

properties,grading

and compaction

requirements.

100mm thick well

graded 5-20mm dia

granular surface

layer.

200mm thick Type1

un-bound mixture

for gravel access

track. Refer to note5

for material

properties, grading

and compaction

requirements.

0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

1.0

0 1

1

SCALE BAR

10 2 5

1:100

0.3

5

0.25

Class 6G selected


rock fill. Refer to

note 5 for material

properties and

grading

requirements.

Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.50 m








vetiver planting





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

2

1 0.501.65

0.3

0

0.50

(23)dd=2.60

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

2/41:100

PRTW.04

(CH 0+480)

MR.004


HFL(117.81)

River Side



2

1

2.85

Freeboard 1.50

4.503.00 1.50

7.50

3.00

1.50

d=3.20

3.00

To be excavated






note 5 for material



100mm thick well

graded 5-20mm dia


200mm thick Type 1


gravel access




requirements.

0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

1.3

3 1

1

SCALE BAR

10 2 5

1:100

0.3

5


granular material for rock

fill. Refer to note 5 for

material properties and

grading requirements.

Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.30 m








vetiver planting

Non-woven

geotextile

(refer note 5)





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

2

1 0.501.65

0.3

0

0.50

(23)d

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

3/41:100

PRTW.04

(CH 0+695)

MR.004


HFL(117.25)

River Side

To be excavated



1

2.85

Freeboard 1.50

4.503.00 1.50

7.50

3.00

1.50

d=2.70

3.00






note 5 for material



100mm thick well

graded 5-20mm dia

granular surface

layer.

200mm thick Type1

un-bound mixture

for gravel access

road.Refer to note5

for material

properties, grading

and compaction

requirements.

0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

1.0

0

1

1

SCALE BAR

10 2 5

1:100

0.3

5



rock fill. Refer to note 5

for material properties

and grading

requirements.

Non-woven

geotextile

(refer note

5)





3.00 x 1.50 x 0.40 m








vetiver planting

Non-woven

geotextile

(refer note 5)





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

2

1 0.501.65

0.3

0

0.50

(23)d

15.00

3.004.506.00

3.007.504.50

SECTION B-B

Scale 1:200

Downstream Upstream

7.50

0.750.75

0.750.75

0.60

0.757.50

12.00Gabion launching apron

(gabion box: 3.00m x 1.50m x 0.60m)

Gabion spur


SECTION A-A

Scale 1:200

19.50

0.600.75

0.75

0.75

Gabion revetment

Geotextile



3.0

04.5

06.0

0

4.5

03.0

0

19.507.50

15.0

0 12.00

PLAN VIEW (TYPE -5)

Scale 1:200

Upstream

Downstream

A

B

B

A

7.5

0

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.04

MR.004


0 6 12 18 24 30

Scale Bar : 1:200

3REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

110

111

112

113

114

115

116

117

118

119

11

7.5

82

11

7.6

54

11

7.5

60

11

7.7

27

11

7.6

07

11

7.4

88

11

7.2

48

11

7.0

09

11

7.2

19

11

6.5

96

11

6.4

22

11

6.3

54

11

5.9

20

11

5.5

90

11

5.2

61

11

5.3

21

11

5.4

22

11

5.5

39

11

5.6

34

CHAINAGE : 0+000.00 - 0+785.00

120

121

122

11

8.9

31

20

.43

11

8.6

11

20

.11

11

8.0

21

19

.52

11

7.8

91

19

.39

11

7.7

41

19

.24

11

7.6

11

9.1

CHAINAGE (km)

0+

00

0.0

0

0+

05

0.0

0

0+

10

0.0

0

0+

15

0.0

0

0+

20

0.0

0

0+

25

0.0

0

0+

30

0.0

0

0+

35

0.0

0

0+

40

0.0

0

0+

45

0.0

0

0+

50

0.0

0

0+

55

0.0

0

0+

60

0.0

0

0+

48

0.0

0

11

8.9

51

20

.45

0+

52

0.0

0

11

8.1

26

11

9.6

26

11

5.4

11

17

.71

51

19

.21

5


EMBANKMENT

WATER LEVEL(masl)

LEVEL (masl)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.04


MR_LP_04

01


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

110

111

112

113

114

115

116

117

118

119

11

6.3

34

11

6.3

10

11

6.3

95

11

6.3

11

11

6.2

58

11

6.1

90

120

121

122

11

6.9

21

18

.42

0+

65

0.0

0

0+

70

0.0

0

0+

75

0.0

0

0+

78

5.0

0DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.04


MR_LP_04

02


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

PRTW-05aSpur


No. of Spurs:

Spur Dimension


Embankment

Revetment

Spurs

(Type 6)0+000m 0+240m

9

30

12 7.5 3

0+000m 0+470m 470m

Spurs

Spacing(m)


240m

0+200m 0+470m 270m

Co-ordinates

SOP Northing

(m)Easting

(m)

1

2

Elevation

(masl)

564744 2952134

564706 2951871

135.25 m

133.74 m

0+000m

0+470m

0+200m

AMR.05a_1

BMR.05a_2

0 25

SCALE BAR 1:2500

50 200100


culvert for toe-drain; see

note 12

SOP1

SOP2

Revetment to tie in to

natural ground

Embankment to tie in

to natural ground

Embankment to tie in to natural

ground. Proposed tie in length of

50m to reach high ground; to be

confirmed on site. See note 11

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview



AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_05a

3


PRTW.05a

01

1:2500BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE


REVETMENT

GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

1/31:100

PRTW.05a

(CH 0+090)

MR.05a


HFL(134.44)

River Side


2

1

2.65

Freeboard 1.50

Non-woven

geotextile

(refer note 5)

6.003.00

6.003.00

3.00

3.00

To be excavated




Sub-Project: Mawa Ratuwa Basin REVISION: 3

SCALE BAR

10 2 5

1:100





3.00 x 1.50 x 0.50 m






BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

0.50

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

2/31:100

PRTW.05a

(CH 0+340)

MR.05a


HFL(132.95)

River Side


2

1

2.65

Freeboard 1.50

6.003.00

6.00

3.00

3.00

3.00

To be excavated


d=0.50






note 5 for material




5-20mm dia granular

surface layer.

200mm thick Type1

un-bound mixture

for gravel access


for material

properties, grading

and compaction

requirements.

0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

SCALE BAR

10 2 5

1:100

0.3

5

0.25

Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.40 m








vetiver planting

Non-woven

geotextile

(refer note 5)





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

21

0.50

1.65

0.3

0

0.50

18.00

3.004.506.00

4.507.506.00

SECTION B-B

Scale 1:200

Downstream Upstream

7.50

0.750.75

0.750.75

0.60

0.759.00

12.00Gabion launching apron(gabion box: 3.00m x 1.50m x 0.60m)

Gabion spur


SECTION A-A Scale 1:200A

21.00

0.600.75

0.75

0.75

Gabion revetment

Geotextile



3.0

04.5

06.0

0

6.0

04.5

0

21.009.00

18.0

0 12.00

PLAN VIEW (TYPE -6)

Scale 1:200

Upstream

Downstream

A

B

B

A

7.5

0

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.05a

MR.005a


0 6 12 18 24 30

Scale Bar : 1:200

3REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

130

131

132

133

134

135

136

137

138

139

130

131

132

133

134

135

136

137

138

139

13

7.4

25

13

7.3

34

13

7.2

43

13

7.1

52

13

7.0

61

13

6.9

70

13

6.7

88

13

6.4

30

13

5.8

96

13

5.3

62

13

4.8

59

13

4.4

06

13

4.0

97

13

3.9

43

13

3.5

72

13

3.1

41

13

2.7

97

13

2.9

72

CHAINAGE : 0+000.00 - 0+470.00

13

5

13

4.0

2

13

3.5

18

13

5.0

18

13

2.7

51

34

.25

13

2.4

51

33

.95

13

2.3

11

33

.81

CHAINAGE (km)

0+

00

0.0

0

0+

05

0.0

0

0+

10

0.0

0

0+

15

0.0

0

0+

20

0.0

0

0+

25

0.0

0

0+

30

0.0

0

0+

35

0.0

0

0+

40

0.0

0

0+

45

0.0

0

0+

47

0.0

0

13

5.1

8

0+

42

0.0

0


EMBANKMENT

WATER LEVEL(masl)

LEVEL (masl)

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION




(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


PRTW.05a


MR_LP_05a

01


DATE:

27/09/19

BEEZAN KHADKA

CARRIE ELLER

AHBAR CHOUDHURY

REVISION: 3

KRISHNA P. SUVEDI

H=1:1000

V=1:100BK

KPS

CE

AC

A3

PRTW-05bSpur


No. of Spurs:

Spur Dimension


Embankment

Revetment

Spurs

(Type 6)0+000m 0+200m

8

30

12 7.5 3

0+000m 0+250m 250m

Spurs

Spacing(m)


200m

250m0+000m 0+250m

Co-ordinates

SOP Northing

(m)

Easting

(m)

1

2

Elevation

(masl)

564728 2952700

564747 2952452

138.37 m

137.13 m

0+000m

0+250m

AMR.005b_1

SOP1

SOP2


existing embankment

Embankment to tie

in to natural ground

0 25

SCALE BAR 1:2000

50 100

CHECKED BY:

DRAWN BY:

DESIGNED BY:

APPROVED BY:

NAME SCALE

Overview



AND IRRIGATION


AND IRRIGATION






Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

REVISION:

MR_OV_05b

3


PRTW.05b

01

1:2000BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

DATE:

27/09/19

BK

KPS

CE

AC

A3

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:

NAME SCALESIGNATURE



GOVERNMENT OF NEPAL


AND IRRIGATION


AND IRRIGATION


Drawing Title

MOTT MACDONALD

IN ASSOCIATION WITH


SHEET NO:

DWG NO:

DATE:

27/09/19

1/21:100

PRTW.05b

(CH 0+120)

MR.005b


HFL(136.11)

River Side


2

1

2.43

Freeboard 1.50

6.003.00

6.003.00

3.00

3.00

To be excavated


d=0.50






note 5 for material



100mm thick well

graded 5-20mm dia


200mm thick Type 1


gravel access




requirements.

0.2

0

0.1

0 0.504.00

0.50

5.00

REVISION: 3

SCALE BAR

10 2 5

1:100

0.3

5

0.25

Non-woven

geotextile

(refer note 5)





3.00 x 1.50 x 0.40 m








vetiver planting

Non-woven

geotextile

(refer note 5)





to note 5)

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3

2

1

0.50

1.65

0.3

0

0.50

0.759.00

12.00Gabion launching apron(gabion box: 3.00m x 1.50m x 0.60m)

Gabion spur


SECTION A-A Scale 1:200A

21.00

0.600.75

0.75

0.75

Gabion revetment

Geotextile



18.00

3.004.506.00

4.507.506.00

SECTION B-B

Scale 1:200

Downstream Upstream

7.50

0.750.75

0.750.75

0.60

3.0

04

.50

6.0

0

6.0

04

.50

21.009.00

18

.00 12.00

PLAN VIEW (TYPE -6)

Scale 1:200

Upstream

Downstream

A

B

B

A

7.5

0

DRAWN BY:

DESIGNED BY:

CHECKED BY:

APPROVED BY:



AND IRRIGATION


AND IRRIGATION

Water Resources Project Preparatory Facility

Jawalakhel, Lalitpur



(GRANT NO:0299-NEP)


MOTT MACDONALD

IN ASSOCIATION WITH


DWG NO:

SHEET NO:


1:200

PRTW.05b

MR.005b


0 6 12 18 24 30

Scale Bar : 1:200

3REVISION:DATE:

27/09/19

BEEZAN KHADKA

KRISHNA P. SUVEDI

CARRIE ELLER

AHBAR CHOUDHURY

BK

KPS

CE

AC

A3