chapter 3 streamflow estimation by msma

BFW 40103- Water Resources Engineering

Chapter 3: P kfl E ti ti B U iPeakflow Estimation By Using Urban StromwaterManagement (MASMA)

Prepared by:Prepared by:

Mohd Shalahuddin Adnan

Lesson goals

At the end of this topic, student should be ableto:-

Understand the application of MSMA in MalaysiaMSMA in Malaysia

Determine the concept of on-siteDetermine the concept of on site retention and on-site detention

Differentiate the uses of OSD and OSR

Design OSD for small area (residential area)(residential area)

1.0 Beauty of Rivers in MalaysiaIntroduction

y y

Almost all major town in Malaysia are located beside a river.

1 1 C t D l t I & D i

Introduction

1.1 Current Development Issues & DrainagePractice

It is widely recognised that landuse changes from rural tourban or industrial areas cause local runoff impacts onurban or industrial areas cause local runoff impacts onreceiving water flow, quality, and ecology.

Erosion and sedimentation problems associated withdevelopment, it has become increasingly apparent thatstormwater runoff contributes to receiving waters asignificant part of total loads of such pollutants as nutrients(including phosphorus and nitrogen) heavy metals oil and(including phosphorus and nitrogen), heavy metals, oil andgrease, bacteria, etc.

Over the years flood damage and adverse impacts onOver the years, flood damage and adverse impacts onwater quality, fisheries, scenic river areas, and wildlifehabitats have been recognised as shortcomings of long-g g gaccepted approaches to the planning, design, andmanagement of storm drainage facilities in urban areas.

As a result rivers, lakes, ponds, reservoirs, and estuarineand coastal waters have become sensitive to increasedand coastal waters, have become sensitive to increasedrates and volumes of runoff and pollutant discharges.These discharges have posed major issues to many urbang p j yand residential centres, particularly in the western states ofthe Peninsula.

The problems have become even more aggravated byfrequent intense rainfalls the physiological nature offrequent intense rainfalls, the physiological nature ofbasins, and the pattern of urbanisation with relatively poorurban services.

1 2 Existing Drainage Practices

Introduction

1.2 Existing Drainage PracticesPresent experience indicates that rapid disposal, localised, reactive,and mono-functional drainage concepts have been widely practisedin Malaysia.

In Malaysia, urban drainage practice has been largely based on the1975 DID Urban Drainage Design Manual

IntroductionNew, comprehensive, and integrated SWM strategies are

d d t b i li ith th t’ d i tnow needed to be in line with the government’s drive toachieve a sustainable developed nation status in the early21st century21 century.

Such new strategies will incorporate runoff source control,management and delayed disposal on a catchment wide,proactive, and multi-functional basis. This should result infl d fl d ti t lit i t dflood flow reduction, water quality improvement, andecological enhancement in downstream receiving waters.

To some extent, it should also contribute to improved urbanamenity through the application of wetlands, landscape forrecreation, potential beneficial reuse of stormwater(especially as a non-potable supply source), and recharge ofd l t d b d t if t h tdepleted urban groundwater aquifers to enhance streambaseflow during dry seasons.

2 0 MSMA

Urban Stormwater Management Manual

2.0 MSMA

MSMA (Manual Saliran Mesra Alam), an( )abbreviation from Malay Languagetranslation of Urban StormwaterM t M l h b id lManagement Manual, has been widelyaccepted term and since become trade markin the stormwater industry in Malaysiain the stormwater industry in Malaysia.

The first edition of the Manual, published in2000, has served as invaluable referencesfor both authority and private professionals.

MSMA 2nd Edition was published in 2012 after ten(10) years time lapse theafter ten(10) years time lapse, the Department decided that it is timely for the first edition be improved.

2 1 Principles of Quantity Control


2.1 Principles of Quantity Control

To reduce flows from a developing areap g To remedy a situation where the downstream drainage system

is undersized, and cannot be enlarged convenientlyTo develop the most cost effective drainage system by To develop the most cost-effective drainage system, byreducing the sizes and cost of downstream pipes and channels,or as long as this reduces the overall net cost of the totaldrainage works

Storm ater q antit control facilities can be classified


Stormwater quantity control facilities can be classified by function :

detention facilities detention facilities retention facilities

Detention and retention storages may be named on the basis of their location and size

New Development and Redevelopment should implement detention and / or retention inimplement detention and / or retention in accordance with the Strategic Plan for the catchment

Existing Urban Areas - community / regional detention or retention may be a viable approach if sufficientor retention may be a viable approach if sufficient open space is available

2 2 Benefits of MASMA application are:


2.2 Benefits of MASMA application are:

Fl d flWater

lit

Ecological enhancem

t i

improved urban

amenity

recharge of depleted

urban Flood flow reduction

quality improveme

nt

ent in downstream receiving

waters

ythrough the application

of tl d

groundwater aquifers to enhance waters, wetlands,

landscape for

recreation

stream baseflowduring dry seasonsrecreation, seasons.

3 0 O Sit D t ti P d

On site Detention (OSD)

3.0 On-Site Detention Pond

Definition: A system that collects conveys and dischargesDefinition: A system that collects, conveys and discharges stormwater runoff from the drainage basin to designated outflow collection points. Typically used in urbanized areas

Detention basin: a natural or artificial basin that receives and temporarily holds storm runoff to reduce downstream peak flows for flood control purposespeak flows for flood control purposes.

Drainage pipe or channel: part of a stormwaterconveyance system that transport stormwater from oneconveyance system that transport stormwater from one place to another

Elements of designElements of design- hydrology: design flow and volume- hydraulics: inlet, conveyance in open channel and closed conduit temporary storage in detention basin & outfallconduit, temporary storage in detention basin, & outfall.


3 1 D t ti F iliti Obj ti3.1 Detention Facilities – Objective

The detention facilities is to reduce peak discharge by theThe detention facilities is to reduce peak discharge by thetemporary storage and gradual release of stormwater runoffby way of an outlet control structure or other releasey ymechanism.

3.1.1 Choice of Detention / Retention Facilities

On-site detention (OSD) may be provided as above-groundstorages, below-ground storages, or a combination of both.


3.2 OSD : Above vs. Below Ground

The main advantages of above-ground:

The main advantages of below-groundg

easily incorporated into the site

g out of sight, occupy less

physical space relatively inexpensive

compared to below- will not cause any

inconvenience with ground storages. ponding of water

** Safety features such as sign board and fencing must be incorporated in thedesign of above-ground storage to prevent drowning, particularly of children andsenior citizense o c e

3 3 O it D t ti (OSD)


3.3 On site Detention (OSD)

3 3 1 Location of Facilities


Car Park Detention Infiltration Trench(CIRIA, 1996)

3.3.1 Location of Facilities

Park Pond

LEVELS

On-site

Regional

Community

LEVELS

Infiltration Basin

Artificial Recharge(Todd, 1980)

Storage Reservoir(Hall, et al., 1993)

Facilities can also be categorised as:


Facilities can also be categorised as:on-line storage : a facility that intercepts flow directly within aconveyance system.off-line storage : the diversion of flow from a conveyance systeminto a separate storage facility.

Online Off-lineOnline Off line

3 3 4 Type of OSD


3.3.4 Type of OSD

Rooftop

Car Parking andSurface Tank Car Parking andDriveway Areas

Landscaped Area

Surface Tank

Landscaped Area

Underground Tank Pipe Package

3 3 5 Ill t ti f C it St S t


3.3.5 Illustration of a Composite Storage System

Maximum ponding level ford i

Freeboardto building

Habitablebuilding

storage design storm

Above-ground storage

to buildingfloor level

g

'Beginning to pond' levelfor above-ground storage

Below-ground storage

g g

g g

Outlet to public drainage system(preferably free draining, butmay be pumped in some cases)

3 3 6 Typical Multi-Purpose Surface TankOn site Detention (OSD)

Roof drainage system

3.3.6 Typical Multi Purpose Surface Tank

g yScreen

P i

ildi

Secondaryoutlet OSD

t

Primaryoutlet

Buildingstorage

Storage forre-use

Above Ground


Runoff

Directon

Lot drainage system

Garage

Swal

e dr

ain

Above-Ground Storage System

w a

roun

d O

SD s

tora

ge

Area draining toOSD storage

Lot drainage system

d di

vert

ups

trea

m f

lowOSD storage

Dwelling

Runoff

Directon

e dr

ain

to in

terc

ept

and

ARunoff

Directon

Swal

e

DCP

Brick retaining wall

OSD Storage

A

Open drain

Brick retaining wall(secondary outlet)OSD Storage

Secondary outletSTREET

Open drainDCP(primary outlet)

SECTION A-A

Secondary outlet

k

AComposite


Car park storage

SW

SWPipe package(2 x 900 mm pipes)

Primary outlet(flow restricting pipe)

Composite Storage System

ALot pipedrainage

System

Offi b ildir pa

rk a

nd a

cces

s

gsystem

Office building

Car

STREET

Secondary outlet(overflow over kerb)

Car park storageOfficebuilding

Pipe package(2 x 900 mm pipes)

Primary outlet

SECTION A-A

Above Ground OSDOn site Detention (OSD)bo e G ou d OS

Landscaping OSDOn site Detention (OSD)

Landscaping OSD

Car-Park OSDOn site Detention (OSD)

Car-Park OSD


Access and overflow grate

Inlet pipes

STORAGE TANKOutlet pipe

Access ladder

Inlet pipes

Trash screen


The Modular Storage The Modular Storage SystemSystem

Pan SuteraOn site Detention (OSD)


3 4 C it d R i l D t ti3.4 Community and Regional Detention

Typically used in Area > 0.1haTypically used in Area > 0.1ha

Community and regional detention facilities are larger facilities than OSD which are located in public areas outside of private properties

Community and regional detention facilities should be l d i h d h ti ti t h i danalysed using a hydrograph estimation technique and

preferably using a computer model


3 5 D t ti F iliti3.5 Detention Facilities

Dry detention pond - release all the runoff temporarilyDry detention pond release all the runoff temporarily detained during a storm. commonly used for controlling peak flow .

Wet Detention pond - incorporate a permanent pool of water for water quality control as well as provision for thewater for water quality control as well as provision for the temporary storage and release of runoff for flood control.

3 5 1 Type of DetentionOn site Detention (OSD)

Design Flood level

3.5.1 Type of Detention

Design Flood level

(a) DRY BASIN

Maximum pond level

Design Flood level

Maximum pond level

(b) WET BASIN(flood storage within ponds and lakes)(flood storage within ponds and lakes)

3 6 Safety features for open space pond3.6 Safety features for open space pond

3 7 Example of dry detentionOn site Detention (OSD)

3.7 Example of dry detention

Example of dry detention


Example of dry detention

Example of wet detention


Example of wet detention

3.8 Detention System (1970)On site Detention (OSD)

3.8 Detention System (1970)

3 8 Detention Facilities (1990)On site Detention (OSD)

3.8 Detention Facilities (1990)

3.9 Dry Detention – Dry PeriodsOn site Detention (OSD)

3.9 Dry Detention Dry Periods


3.9 Dry Detention – After Heavy Rain3.9 Dry Detention After Heavy Rain

3.10 Example of Detention FacilitiesOn site Detention (OSD)

3.10 Example of Detention Facilities


3.10 Malaysia Experiences3.10 Malaysia Experiences

On Site Retention (OSR)

4 0 O Sit R t ti P d4.0 On-Site Retention Pond

Retention Concept :Retention Concept :

Retaining and having a portion of the stormwater infiltrate or percolate into the soil and the groundwater systempercolate into the soil and the groundwater system

Detention VS RetentionDetention VS Retention The reduced post-development runoff hydrograph is

designed so that the peak flow is equal to or less than thedesigned so that the peak flow is equal to or less than the pre-development peak flow rate. (detention/retention facilities)

The volume of the post-development hydrograph is required to be reduced to the same volume as the pre-development runoff hydrograph. (retention facilities)


4 1 R t ti F iliti4.1 Retention Facilities

The retention facilities reduce runoff volume and possiblyThe retention facilities reduce runoff volume, and possibly peak discharge, by the temporary storage of stormwaterrunoff, which is subsequently released via evaporation/evatransporation and infiltration.

4.2 Advantages of Rentention reduction of downstream flow peaks (p)p (p) smaller storm drains at a lesser cost (p) recharge of groundwater (s)g g ( ) reduction in the settlement in groundwater depletion areas control of saline water intrusioncontrol of saline water intrusion reduction of pollution transported to receiving waters (p)

4.3 Infiltration and Artificial Recharge System On Site Retention (OSR)

g yused for Stormwater Disposal (CIRIA, 1996)


4 3 T R t ti F iliti4.3 Type Retention Facilities

extended detention facilitiesextended detention facilitiesinfiltration structuresswalesporous pavement

4.3.1 On-Site & Community Retention

The main types of retention/infiltration techniques are infiltration trenches, soakaway pits, porous pavement and infiltration basinsinfiltration basins

4.3.1.1Soakaway PitOn Site Retention (OSR)

4.3.1.1Soakaway Pit

4.3.1.2 Porous PavementOn Site Retention (OSR)

4 3 1 3 Typical Cross-section of PorousOn Site Retention (OSR)

4.3.1.3 Typical Cross-section of Porous Pavement Structure (Raimbault, 1997)

4.3.1.4 Infiltration Trench (Schueler, 1987)On Site Retention (OSR)

( , )

4.3.2 Examples of Retention FacilitiesOn Site Retention (OSR)

pMalaysia Case Study


LooseLoose--Rock Infiltration Rock Infiltration B iB iBasinBasin

4 4 Regional RetentionOn Site Retention (OSR)

4.4 Regional Retention

It is more cost-efficient to implement large scalestormwater retention facilities in conjunction with artificialgroundwater recharge/ groundwater management

f itprogramme of a community.

4.4.1 Example of Regional RetentionOn Site Retention (OSR)

4.4.1 Example of Regional Retention

4.5 General Design ConsiderationsOn Site Retention (OSR)5 Ge e a es g Co s de at o s

On Site Retention (OSR)4.5 General Design Considerations

On-site Detention

5 Ge e a es g Co s de at o s

Simplified hydrographs are combined with an assumedoutlet relationship to determine a critical volume of water tooutlet relationship to determine a critical volume of water tobe stored. A storage is then to be provided for this criticalvolume.

Community and Regional Detention

Design and analysis involve :hydrological calculations to determine the storage y g gvolumehydraulic calculations to route the flows and d t i th d ti i fl tdetermine the reduction in flowratesgeotechnical, structural, and other design processes

On Site Retention (OSR)4.5 General Design Considerations

Retention

5 Ge e a es g Co s de at o s

The surface soils and geohydrologic conditions at the it h t b k d d t dsite have to be known and understood.

This include data on soil profiles, soil permeabilityand porosity and groundwaterand porosity, and groundwater.

The local soil should be (a) permeable( ) p (b) unsaturated

Approximate Value for Soil Porosity (CIRIA, 1996)On Site Retention (OSR)pp y ( , )

Soil Propoerties Classified by Soil TextureOn Site Retention (OSR)

p y


Special Consideration

The retention system should be designed to emptyThe retention system should be designed to empty sufficiently before the next rainfall event.

4 7 H d l l l ti

Hydrology Calculation

4.7 Hydrology calculation

Annual Return PeriodAnnual Return Period

for a given rainfall duration and ARI, is a function of the local li t R i f ll d th b f th d dclimate. Rainfall depths can be further processed and

converted into rainfall intensities (intensity = depth/duration), which are then presented in IDF curveswhich are then presented in IDF curves.

The ARI is given by:

1001Tr ………e.q 11.1

g y

100P

Tr ………e.q 11.1

where Tr is the ARI in years and P is the AEP inwhere Tr is the ARI in years and P is the AEP in percent. Hence, a 1% AEP has an ARI of 100 years.

4 7 H d l l l ti


4.7 Hydrology calculation

Polynomial expressions in the form of Equation 13 2 havePolynomial expressions in the form of Equation 13.2 have been fitted to the published IDF curves for the 35 main cities/towns in Malaysia.y

IDF can be generated using Eq. 13.2

32 ))t(ln(d))t(ln(c)tln(ba)Iln( tR ………e.q 13.2

where,Rit = the average rainfall intensity (mm/hr) for ARI and duration tt g y ( )R = average return interval (years)t = duration (minutes)a to d are fitting constants dependent on ARI.

ARI (years) a b c d


2 5.3255 0.1806 -0.1322 0.00475 5.1086 0.5037 -0.2155 0.0112

10 4.9696 0.6796 -0.2584 0.014720 4.9781 0.7533 -0.2796 0.016650 4.8047 0.9399 -0.3218 0.0197

100 5.0064 0.8709 -0.307 0.0186

1000

100

(mm

/hr)

10Rain

fall

Inte

nsity

100 yr50 yrR 50 yr20 yr10 yr5 yr2 yr1 yr ARI

110 100 1000

Duration (minutes)

Note also:Hydrology Calculation

If the drainage area is 10 km2 to 1000 km2 (or 1 107 m2 to 1 109 m2), then the rainfall intensity I = FA I, where FA =

l d ti f t A l d ti f t i id d iareal reduction factor. Areal reduction factor is provided in Table 13.1 (MSMA) or Figure 13.1 (MSMA) as shown below.

rainfall depth,P = I t

Figure 13.1 Graphical Areal Reduction Factor

Example: If the 0.75 hour rainfall intensity computed for a 30 km2

catchment area based on polynomial equation is I = 250catchment area based on polynomial equation is I = 250 mm/hr, based on Figure 13.1 determine the rainfall depth. Account for the variability in rainfall.

yPolynomial equation:

32 ln ln ln ln tdtctbaItR

where, I = intensity (mm/hr)t = duration (minutes)a, b, c and d = coefficients based on ARI and location

0 920.92

30 km2

Since the catchment area A = 30 km2 > 10 km2, then the areal reduction factor is required.Th f th i f ll i t it I F ITherefore, the rainfall intensity I = FA I

I = 0.92 250 mm/hrI = 230 mm/hr

The rainfall depth P = I tP = 230 0.75P = 176.25 mm

Storage Tank Characteristics


Storage Tank Characteristics

Typical storage tanks areTypical storage tanks areeither circular orrectangular in planand/or cross-section but,due to their structuralnature, can beconfigured into almostany geometrical planshape (Table 5.2).

Design Criterias


• Figure 5.A1: 5 (Five) Design Regions;

Design Criterias

• Table 5.A1: Maximum Permissible Site Discharge (PSD) and Minimum Site Storage Requirement (SSR) Values inand Minimum Site Storage Requirement (SSR) Values in Accordance with The Five Regions in Peninsular Malaysia;

• Table 5.A2: Maximum Permissible Site Discharge (PSD), Minimum Site Storage Requirement (SSR) and Inlet Values in Accordance with The Major Towns in Peninsularin Accordance with The Major Towns in Peninsular Malaysia;

• Table 5.A3: OSD Volume, Inlet Size and Outlet Size for Five Different Regions in Peninsular Malaysia;and

• Table 5.A4: Discharge – Pipe Diameter.

Design Considerations


(a) Design Storm ARIThe design storm shall be 10 year ARI in accordance with

Design Considerations

The design storm shall be 10 year ARI in accordance with the minor drainage system ARI provided in Table 1.1.

(b) Permissible Site Discharge (PSD)The PSD is the maximum allowable post-development discharge from a site for the selected design storm and is estimated on the basis that flows within the downstream stormwater drainage system will not be increasedstormwater drainage system will not be increased.

(c) Site Storage Requirement (SSR)(c) S te Sto age equ e e t (SS )The SSR is the total amount of storage required to ensure that the required PSD is not exceeded and the OSD facility does not overflow based on the storage design storm ARI.

Figure 5.A1: Five (5) Design Regions

Table 5.A1: Maximum Permissible Site Discharge (PSD) and Minimum Site Storage Requirement (SSR) Values in Accordance with The Five Regions in Peninsular Malaysia

Table 5.A2: Maximum Permissible Site Discharge (PSD), Minimum Site Storage Requirement (SSR) and Inlet Values in Accordance with The MajorStorage Requirement (SSR) and Inlet Values in Accordance with The Major Towns in Peninsular Malaysia

Table 5.A3: OSD Volume, Inlet Size and Outlet Size for Five Different Regions in Peninsular Malaysia

Table 5.A4: Discharge and Pipe Diameter Relationship

Design Steps


A step by steps procedure for designing storage system of OSD are as follows:

Design Steps

are as follows:

Step 1: Determine the storage type(s) to be used within the site, i.e. separate above and/or below-ground storage(s), or a composite above and below- ground storage.Step 2: Identify the region of the detention site from Figure 5 A1Step 2: Identify the region of the detention site from Figure 5.A1.Step 3: Determine the catchment characteristics such as terrain type and percentage of impervious area.St 4 D t i P i ibl Sit Di h (PSD)Step 4: Determine Permissible Site Discharge (PSD) per hectares (PSD/ha) from Table 5.A1. Then multiply with project area to determine PSD.area to determine PSD.Step 5: Determine Site Storage Requirement (SSR) per hectares (SSR/ha) from Table 5.A1. Then multiply with project area to d t i SSRdetermine SSR.

Step 6 Identif the major to n of the detention site in Table


Step 6: Identify the major town of the detention site in Table 5.A2 and determine inlet flow per hectares from Table 5.A2 . Then multiply with project area to determine inlet flow.p y p j

Step 7: Determine PSD per hectares (PSD/ha) from Table 5 A2 Then multiply with detention area to determine PSD5.A2. Then multiply with detention area to determine PSD.

Step 8: Determine SSR per hectares (SSR/ha) from Table 5.A2. Then multiply with detention area to determine SSR.

Step 9: Compare the value of PSD from Step 4 and Step 7Step 9: Compare the value of PSD from Step 4 and Step 7. The smaller PSD value is adopted for subsequent sizing of outlet pipe.

Step 10: Compare the value of SSR from Step 5 and Step 8. The larger SSR value is adopted for Selected Design ValueThe larger SSR value is adopted for Selected Design Value.

Step 11 Determine the Inlet Pipe diameter from Table 5 A3


Step 11: Determine the Inlet Pipe diameter from Table 5.A3.

Step 12: Determine the Outlet Pipe diameter from Table 5.A3.p p

Step 13: Determine the Inlet Pipe diameter from Table 5.A4 by using the Inlet Flow value from Step 6 as dischargeusing the Inlet Flow value from Step 6 as discharge.

Step 14: Determine the Outlet Pipe diameter from Table 5.A4 by using the PSD value from Step 9 as discharge.

Step 15: Compare the value of Inlet Pipe diameter and fromStep 15: Compare the value of Inlet Pipe diameter and from Step 11 and Step 13. The smaller Inlet Pipe diameter is adopted for Selected Design Value.

Step 16: Compare the value of Outlet Pipe diameter and from Step 12 and Step 14 The smaller Outlet Pipe diameter isStep 12 and Step 14. The smaller Outlet Pipe diameter is adopted for Selected Design Value.

A multi-purpose hall is to be developed within UiTM Kuala Pilah campus area.

Design Example 1 –Using MSMA 2nd edition A multi purpose hall is to be developed within UiTM Kuala Pilah campus area. The project area is 0.61ha. 75% of it shall be occupied by building, access road and pavement while 25% by garden and turfed areas. The catchment area of the project where it connects to the main drain is 0.61ha and has a p jterrain slope of about 1:2000. It is more economical to construct an OSD tank than to upgrade the existing drainage system for this new development. Based on the design procedure, calculate the Permissible Site Discharge (PSD), Site g g ( )Storage Requirement (SSR) and the inlet and outlet pipe sizes.

Underground OSD Tank

Figure; Multi-Purpose Hall Layout at UiTM Kuala Pilah

Solutions:

Design Example 1 –Using MSMA 2nd edition

References Calculation Output

Solutions:

Figure 5.A1 Kuala Pilah falls under Region 1 — West Coast. So, use OSD Characteristic for Region 1— West Coast.1 West Coast.Project Area = 0.61haTerrain = Mild% of Impervious Area = 75%p

Table 5.A1 Permissible Site Discharge (PSD)/ha:

For area of 0 61 ha PSD =For area of 0.61 ha, PSD

Table 5 A1 Site Storage Requirement (SSR)/ha:Table 5.A1 Site Storage Requirement (SSR)/ha:

For area of 0.61ha, SSR =

Solutions:



Solutions:

Table 5.A2 Inlet Flow/ha:

For area of 0.61 ha, Inlet Flow =

Table 5.A2 Inlet Flow/ha:

For area of 0.61 ha, Inlet Flow =

Table 5 A2 SSR/ha:Table 5.A2 SSR/ha:

For area of 0.61 ha, SSR =

Smaller PSD value is adopted for subsequent sizing of outlet pipe.Thus, PSD =

Solutions:



Solutions:

Table 5.A3 Inlet Pipe:(adopt 450mm dia. as it is readily available in the market)

Table 5.A3 Outlet Pipe:p(adopt 160mm dia. as it is readily available in the market)

Table 5.A4 Inlet Pipe: (with Inlet Flow of )Table 5 A4 Outlet pipe: (with PSD of )Table 5.A4 Outlet pipe: (with PSD of )

Design values selected



Design values selected

PSD whichever is smaller from Table 5.A1 and 5.A2SSR whichever is larger from Table 5.A1 and 5.A2Sizing of OSD Tank: The required storage is 273 6m3Sizing of OSD Tank: The required storage is 273.6m3

Adopt tank width of 20m, 12m length and a depth of 1.2m.Tank storage = 20m x 12m x 1 2mTank storage = 20m x 12m x 1.2m

Inlet Pipe whichever is smaller from Table 5.A3 and 5.A4Outlet Pipe whichever is smaller from Table 5.A3 and 5.A4

Figure 5.B1.2: Typical Detail Drawing for Below-Ground OSD Tank

Above Ground OSD Tank


There is a tennis court located next to a multipurpose building of UiTM in Kluang, Johor. OSD tank needs to be built for the same reason as in Design

Above Ground OSD Tank

Example 5.B1. The tennis court area is 0.7ha and 60% of it shall be paved.The catchment area of the project that connects to the main drain is about 0.7ha with a slope of about 1: 1800.

Figure ;Tennis Court at UiTM Kluang

Solutions:



Solutions:

Figure 5.A1 Kluang falls under Region 5 - Southern.So, use OSD Characteristic for Region 5—Southern.Southern.Project Area = 0.70haTerrain = Mild% of Impervious Area = 60%p

Table 5.A1 Permissible Site Discharge (PSD)/ha:

For area of 0 7 ha PSD =For area of 0.7 ha, PSD

Table 5 A1 Site Storage Requirement (SSR)/ha :Table 5.A1 Site Storage Requirement (SSR)/ha :

For area of 0.7ha, SSR =

Solutions:


References Calculation OutputTable 5 A2 Inlet Flow:

Solutions:

Table 5.A2 Inlet Flow:As Kluang is not in the list in Table 5.A2, refer to Table 5.A3 only.

T bl 5 A2 PSDTable 5.A2 PSD:As Kluang is not in the list in Table 5.A2, refer to Table 5.A1 only.

Table 5.A2 SSR:As Kluang is not in the list in Table 5.A2, refer to Table 5.A1 only.

Table 5.A3 Inlet Pipe:(adopt 400mm Dia. as it is readily available in the market)

Table 5.A3 Outlet Pipe:(adopt 160mm Dia. as it is readily available in the market))

Solutions:


References Calculation OutputTable 5 A4 Inlet Pipe:

Solutions:

Table 5.A4 Inlet Pipe:As Kluang is not in the list in Table 5.A2, no checking for Table 5.A4 is required. Refer to Table 5 A3 onlyTable 5.A3 only.

Table 5.A4 Outlet Pipe:As Kluang is not in the list in Table 5.A2, no checking for Table 5 A4 is required Refer tochecking for Table 5.A4 is required. Refer to Table 5.A3 only.

Sizing of OSD Tank:Th i d t i 286 9 3The required storage is 286.9m3Adopt tank width of 20m, 12m length and a depth of 1.2m.Tank storage = 20m x 12m x 1.2m

Fi 5 B2 2 T i l D t ilFigure 5.B2.2: Typical Detail Drawing for Above-Ground Tank

5 0 R i t H ti

Rainwater Harvesting

5.0 Rainwater Harvesting

1998 drought (El Nino) has caused unpleasant water supply1998 drought (El Nino) has caused unpleasant water supplydisruptions for Klang Valley areas.

May 1998 Ministry of Housing and Local Government hasexpressed the new houses to be designed to include facilitiesfor collecting rainwaterfor collecting rainwater.

June 1999 guideline on “Installing a rainwater collection adng gutilization system” has been released. Nov. 2007 installation ofRWHS is mandatory in new development.

Nov. 2011 Uniform Building by Law officially gazetted thatnew semi-detached houses, bungalows and governmentnew semi detached houses, bungalows and governmentbuildings need to install RWHS. (Five state has implementedthis law- (Melaka, Selangor, Perak, Johor, KL, Kelantan)


Rainwater Harvestingi Nnews in Newspaper


5 1 Wh t i R i t5.1 What is RainwaterHarvesting?

Rainwater harvesting is theaccumulation and storage of rainwateraccumulation and storage of rainwaterfor reuse before it reaches the aquifer.Uses include drinking water, water forlivestock, water for irrigation, etc.

Rainwater collected from the roofs ofRainwater collected from the roofs ofhouses and local institutionscontribution to the availability ofcontribution to the availability ofdrinking water.


5 2 Wh R i t H ti ?5.2 Why Rainwater Harvesting?

i Conserve and supplement existing water resourcesi. Conserve and supplement existing water resources

ii. To reduce soil erosion

iii. Potentially provide improved quality of water

iv. Supply water at one of the lowest costs possible for asupplement supply sourcepp pp y

v. Capturing and directing storm water and beneficially use it

vi. Replenishing local ground water aquifers where loweringof water tables has occurredof water tables has occurred

5 2 1 B fit i R i t M t


Supply of

5.2.1 Benefits in Rainwater Management

Supply of additional

water

Prevention of Urban

Flood

Prevention of river flow

drying

Rainwater Management

Restoration of

Hydrological

Control of non-point

source Hydrological Cycle

Alleviation

source pollutants

of Heat Island


5 3 H ti S t5.3 Harvesting System

Broadly rainwater can be harvested for two purposesBroadly rainwater can be harvested for two purposesStoring rainwater for ready use in containers above or below groundgCharged into the soil for withdrawal later (groundwater recharging)

Source: A Water Harvesting Manual For Urban Areas


5 4 RWH S t5.4 RWH System


5 4 RWH S t

Collection (Catchment) T t ti D t k

5.4 RWH System

Collection (Catchment)Flat / sloping roofs

Transportation: Downtakepipes

Leaf and grit ffilter, First flush device

Storage in tankstanks

Recharge into open wells /Recharge into open wells / borewells / percolation pits / trenches


5 4 RWH S t5.4 RWH System

Image sources ; www.englishecoenergy.com


5 5 E l f I l t d RWH P j t5.5 Example of Implemented RWH ProjectsZoo Negara, KL

DID HQ @ Jalan Sultan SalahudidnDID HQ @ Jalan Sultan Salahudidn, KL

Rumah Panjang, Sarawak

UTHM Hostel


5 5 E l f I l t d RWH P j t5.5 Example of Implemented RWH Projects


5 5 E l f RWH d i b ill5.5 Example of RWH design by villagers


5 6 RWH S ft d l d b NAHRIM5.6 RWH Software developed by NAHRIM

Example calculation using MSMA 1st Edition

Determine the size of an above ground storage for the proposed residential

Design Example – Using MSMA

Determine the size of an above-ground storage for the proposed residentialdevelopment in Kuala Lumpur. The area of the site is 600 m2.

STEP 1 : Determine Storage Volume Required

1. Select storage type to be used within the site.

2. Determine the area of the site that will be directed to the OSD storagegsystem.

The house and garage, part of the concrete driveway, and the backyard will bedrained to the DCP in the OSD storage via a pipe drainage system. A swaledrain is to be provided along the edge of the concrete driveway to preventrunoff from the adjacent lot draining to the OSD storage.

Of the total site area of 600 m2, 547 m2 will drain to the OSD storage.

3 D t i th t f i i d i d i i t th

Design Example

3. Determine the amount of impervious and pervious areas draining to theOSD storage system.

Impervious area:Impervious area:Dwelling = 115.7 m2

Garage = 30.2 m2

Driveway = 40 6 m2Driveway = 40.6 mSurface paving and paths = 49.5 m2

TOTAL = 236 m2

Pervious area:Lawns and Gardens = 311 m2

The site condition before development was park lawn.

Design Example

4 Determine times of concentration t and t4. Determine times of concentration, tc and tcs .

To determine the catchment times of concentration, an analysis of thecatchment drainage system will need to be undertaken.g y

tcs = 20 minutestc = 30 minutesc

5. Calculate the pre and post-development flows for the area draining to the OSD storage.

The minor drainage system that the OSD storage will discharge into has been designed for a 2 year ARI capacity. The rainfall intensity is estimated using

3230

2 ))30(ln(012.0))30)(ln(231.0()30ln(598.0775.4)ln( I

Equation 13.2 (tc 30 minutes) and Table 13.A1 for tc :

I 58.99302

= 4.601

hrmmI

/10058.9930

Design Example Using the Rational Method, the pre and post-development flows are calculatedUsing the Rational Method, the pre and post development flows are calculated as follows:

DevelopmentStatus I

(mm/hr)Impervious Area Pervious Area

Status (mm/hr) ∑CA Q (l/s)C A (m2) C A (m2)

Pre-development 100 - - 0.43 547 235.2 6.5 (Qp)(Qp)

Post-development 100 0.9 236 0.43 311 346.1 9.6 (Qa)

6. Determine the required Permissible Site Discharge (PSD).

Using Equation 19.1 with Equations 19.1a and 19.1b for above-ground storage:Using Equation 19.1 with Equations 19.1a and 19.1b for above ground storage:

1.192

42

baa

PSD

attQQ

ttQa csc

a

pc

c

a 1.1925.075.0333.04

2

bQQb pa 1.194

Design Example

864320250307505.63033306.94

60.2496.9x5.6x4 b

86.4320x25.030x75.06.9

x30x333.030

x4

a

slx

PSD /7.62

60.249486.4386.43 2

7. Determine the required Site Storage Requirement (SSR).

U i E ti 19 2 ith E ti 19 2 d 19 2b f b d t

2

Using Equation 19.2 with Equations 19.2a and 19.2b for above-ground storage, the site discharge for the storage design storm (10 year ARI) and the corresponding SSR is calculated for a range of storm durations to determine the maximum SSR These calculations are summarised in the following two tablesmaximum SSR. These calculations are summarised in the following two tables.

)( 306030 PPFPP Dd )( 306030 Dd

dPI dd

Design Example

t (mins) I (mm/hr) Impervious Area Pervious Area ∑CA Q (l/s)td (mins) I (mm/hr) p ∑CA Qd (l/s)

C A (m2) C A (m2)5 347 0.9 236 0.75 311 445.7 43.0

10 252 0.9 236 0.70 311 430.1 30.115 199 0.9 236 0.63 311 408.3 22.620 165 0.9 236 0.58 311 392.8 18.030 126 0.9 236 0.49 311 364.8 12.835 114 0.9 236 0.46 311 355.5 11.3

td (mins) Qd (l/s) PSD (l/s) c d SSR (m3)5 43.0 6.7 5.46 0.22 11.2

10 30.1 6.7 5.28 0.32 14.715 22.6 6.7 5.08 0.43 15.420 18.0 6.7 4.87 0.54 15.130 12.8 6.7 4.46 0.76 13.635 11 3 6 7 4 28 0 86 13 035 11.3 6.7 4.28 0.86 13.0

From the above table, a maximum SSR of 15.4 m3 occurs at a duration of 15 i t H f l d d t dditi l 20% i dd d t15 minutes. However, for a landscaped storage, an additional 20% is added to the volume to account for inaccuracies in construction and future loss of storage due to the build-up of the lawn surface. Therefore:

Required SSR = 15.4 x 1.2 = 18.5 m3

STEP 2: Size Primary Outlet

Design Example

STEP 2: Size Primary Outlet

The primary outlet orifice is sized to discharge the PSD assuming free outletconditions when the storage is full. Using a 600 mm deep DCP and a maximumco d o s e e s o age s u Us g a 600 deep C a d a a ustorage depth of 300 mm, adopt a maximum head to the centreline of the orificeof 0.8 m. The required orifice size under free outlet conditions is calculated byrearranging Equation 19.3:

23

0027.080x819x2620

107.62

mxHgC

PSDAo

g g q

8.0x81.9x262.02 HgC od

AD o 958058900027.0x44

mmmDo 9.580589.0

Step 3: Increase Storage Volume

Design Example

Step 3: Increase Storage Volume

If the storage capacity needs to be increased to compensate for outletsubmergence the reduced head on the orifice needs to be estimated tosubmergence, the reduced head on the orifice needs to be estimated tocalculate the reduced outflow.

LSVKRLRLH 2

' LSg

KRLRLH fobao 2

RL 1.55

OSD Storage

Sf .LV 2

DCP Hydraulic Grade Line

'oH

Open

KoV 22g150 mm

RL 1.20

pdrainL = 1.0 m

V 2

LSg

VKH fo'

o .2

20.155.12

.

Adopting a 1.0 m long 150 mm UPVC outflow pipe and an outlet loss factor Ko

Design Example o

= 0.5, the reduced outflow Q can be estimated from Equation 19.3 by trial and error. Trial and error calculations are summarised in the following table (pipe velocity V = Q /A and pipe friction slope Sf is obtained from Figure 25.B1).

Trial Q(l/s)

Pipe V(m/s)

(m x 10-3) (m x 10-3) (m)

Estimated Q (l/s)g

VK o 2

2

LSf .'

oH(m x 10 ) (m x 10 3) (m)

3.0 0.170 0.73 2.60 0.347 4.27

4.3 .243 1.51 4.70 0.344 4.25

Reduced outflow Q is estimated to be 4.3 l/s.Repeat 7 in step (1) to obtain the revised SSR:

td (mins) Qd (l/s) PSD (l/s) c d SSR (m3)

5 43.0 4.3 3.59 0.09 11.810 30.1 4.3 3.52 0.13 15.915 22.6 4.3 3.43 0.18 17.120 18.0 4.3 3.35 0.22 17.330 12.8 4.3 3.18 0.31 16.835 11.3 4.3 3.11 0.35 16.5

The revised SSR is 17.3 x 1.2 = 20.8 m3.

Design Example

STEP 4: Determine Storage DimensionsSTEP 4: Determine Storage Dimensions

The storage area = 600 mmMaximum storage = 300 mmMaximum storage = 300 mm

The minimum recommended floor slope is 2%. Assuming the average depth in the storage is 260 mmg

Dimension of the revised storage volume are :

Dimension of the initial storage volume estimate :

16.0 m (length) x 5.0 m (width) x 0.26 m (average depth) = 20.8 m3 (OK)

15.8 m (length) x 4.5 m (width) x 0.26 m (average depth) = 18.5 m3 (OK)

Design Example STEP 5: Size Secondary OutletSTEP 5: Size Secondary Outlet

The secondary outlet is a broad-crested weir slotted into the retaining wall along the front boundary. The weir should be sized for the estimated major system ARI

=

y j yflow from the site for time tcs (20 minutes). The major drainage system in the catchment has been designed for 50 year ARI.

Th 20 i t 50 ARI i f ll i t it f K l L i ti t dThe 20 minute, 50 year ARI rainfall intensity for Kuala Lumpur is estimated using Equation 13.3:

50 mmP 1.67)4.774.99(x47.04.772050

hPI /2011.672050

50 hrmmd

I /201

6020

2020

50

Using the Rational Method, the major system flow is calculated as follows:

I (mm/hr) Impervious Area Pervious Area ∑CA Q (l/s)I (mm/hr) ∑CA Q (l/s)C A (m2) C A (m2)

201 0.9 236 0.63 311 408.3 21.9

Design Example

Assuming the head over the weir is limited to 50 mm and C = 1 70=Assuming the head over the weir is limited to 50 mm and CBCW = 1.70, rearranging Equation 20.5 gives:

Qd 10x921 3

=

mHC

QBBCW

d 15.105.0x70.1

10x9.215.15.1

Allowing 50 mm freeboard, the dimensions of the secondary outlet weir are:

1150 mm (wide) x 100 mm (high)1150 mm (wide) x 100 mm (high)

Design Example

back

1.0Design Example –Using MSMA

0.9

0.8

2

1

0.7

4

3

Coef

ficie

nt,

C

0.6

0.5

5

Runo

ff

0.4

7

6

0.3

0.2

8Impervious Roofs, ConcreteCity Areas Full and Solidly Built Up

Surface Clay, Poor Paving, Sandstone RockCommercial & City Areas Closely Built Up

Semi Detached Houses on Bare Earth3

2

1

0.1

Urban Residential Fully Built Up with Limited GardensBare Earth, Earth with Sandstone Outcrops

Bare Loam, Suburban Residential with Gardens

Widely Detached Houses on Ordinary LoamSuburban Fully Built Upon Sand Strata

Park Lawns and Meadows

Cultivated Fields with Good Growth8

7

6

5

4

Rainfall Intensity, I (mm/hr)

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 1800

190 200

Sand Strata8

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chapter 3 streamflow estimation by msma

Documents

urban areas

infl d fl d ti t

urban drainage practice

d iintroduction1

industrial areas

local runoff impacts

volumes of runoff

t dflood flow reduction