Stormwater Management Plan of Thimphu Thromde

Draft Terms of Reference (2019- 2020)

Flood Engineering and Management Division Department of Engineering Services Ministry

of Works and Human Settlement Thimphu Bhutan

Contents Introduction .................................................................................................................................3

Country Background ............................................................................................................... 3 Thimphu Thromde (Project location) ....................................................................................... 4 Storm water challenges in Thimphu Thromde .......................................................................... 5

Goal and objectives of the assignment .........................................................................................7 Goal ........................................................................................................................................ 7 Objectives ............................................................................................................................... 7 Scope of Work ........................................................................................................................ 7

Available Data ............................................................................................................................7 Digital Elevation Model (DEM) .............................................................................................. 7 Meteorological Data (Rainfall, Maximum Temperature, Minimum Temperature and Relative Humidity) ................................................................................................................................ 7 Hydrology Data ....................................................................................................................... 8 Digitized drainage network of Thimphu Thromde .................................................................... 9 Plot boundary shapefile and other shapefiles ......................................................................... 10

Details of task to be performed .................................................................................................. 10 Task A: Inception report ....................................................................................................... 10 Task B: An Interim report ...................................................................................................... 10 Task C: The Storm Management Plan report .......................................................................... 11

Deliverables, time frame and location ........................................................................................ 11 Deliverables .......................................................................................................................... 11 Timeframe ............................................................................................................................. 12

Management and contribution of counterpart ............................................................................. 12 Composition of the Program Steering Committee (PSC) ........................................................ 13 Roles and Responsibilities of PSC ......................................................................................... 13 Composition of the Task Force Committee (TFC) ................................................................. 13 General roles and responsibility of TFC ................................................................................. 13 Specific responsibilities of TFC members .............................................................................. 14 Communication ..................................................................................................................... 14 Personnel ............................................................................................................................... 14

Reporting .................................................................................................................................. 15

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Figure 1: Bhutan Map Showing Study Area ................................................................................. 4 Figure 2: Poor drainage leading to Urban flooding (Near Immigration Office, Norzin lam) ......... 6 Figure 3: : lack of proper drains lead to discharge of stormwater into street (-Near Tashi Taj) ...... 6 Figure 4: Drain overflows, runoff discharged on road. (-Near Swimming pool roundabout). ........ 6 Figure 5: Drainage blocked lead to discharge of stormwater into the street. (Near Thimphu Dzongkhag office). ...................................................................................................................... 6 Figure 6: Runoff from roads and drains is discharged into the street. (Below changadephu and Buddha point junction). ............................................................................................................... 6 Figure 7: : Household waste dumped into drainage leading blockages(Near Financial Institutions Training Institute Ltd. (FITI)) ...................................................................................................... 6 Figure 8: Location of Meteorological and Hydrology stations in study area ................................. 8 Figure 9: Digitized drainage network of Thimphu Thromde ......................................................... 9

Table 1: Digital Elevation Model (DEM) available in study area ................................................. 7 Table 2: Available meteorological station data. ............................................................................ 8 Table 3: Available Hydrology data .............................................................................................. 8 Table 4: Schedule for deliverables ............................................................................................. 12 Table 5: Responsibilities of Task Force Committee ................................................................... 14 Table 6: Description of specific field of expertise required. ........................................................ 15

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Introduction Country Background

Bhutan is a small landlocked country located in the eastern part of the Himalayan range between 88°E and 93°E longitudes and 26°N and 29°N latitudes. The land elevation ranges from 97m in the southern foothills and gradually rising to about 7,541m towards the north with a total area of 38394 sq.km. The land consists mostly of steep and high mountains crisscrossed by a network of swift rivers, which form deep valleys before draining into the Indian plains. Geographical diversity combined with equally diverse climate conditions contributes to Bhutan's outstanding range of biodiversity and ecosystems. Bhutan can be broadly divided into six Agro-ecological zones with temperatures varying from -5°C to 35°C.

Bhutan is known for its commitment to environmental sustainability and conservation. Environmental conservation is at the core of Bhutan’s Development Strategy, “the middle path.” The constitution requires maintaining at least 60% of its land under forest covers for all times to come. Currently, more than 50% of the total land area is under protected area systems and networks of biological corridors. All of Bhutan's protected land is interconnected through a vast network of biological corridors, allowing animals to migrate freely throughout the countryside.

Extreme weather events like heavy rains during summer triggering flash floods and landslides, urban floods and little or no rain during winter, along with seasonal drought and occasional hailstorms, are increasingly damaging Bhutan’s infrastructures, crops, and livelihoods. Most villages across Bhutan are highly vulnerable to climate impacts and have low adaptive capacity attributed to their limited resource base and precarious socioeconomic status. The total population in Bhutan in 2017 amounted to 779,666 with 404,347 males and 375,319 females.

The structure of the Bhutanese economy has undergone significant changes over the past several years. The electricity and water sectors account for 14.34%, agriculture and forestry account for 16.67%, and, construction infrastructure accounts for 15.61% of Bhutan’s GDP growth in 2016. As compared to the growth rate in 2016, the overall GDP growth in 2016 has increased to 7.99 percent (i.e. up by 1.39 percent as compared in 2015). However, climate change variability and extremes are wreaking havoc on the productivity and performance of these and other socio- economic development sectors and therefore, in the 12th Five Year Plan (July 2018 to June 2023) Environment, Climate Change and Poverty are prioritized by the government as a serious concern.

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Thimphu Thromde (Project location)

Thimphu, the biggest and capital city of Bhutan is situated at the western central part of Bhutan between 27°28′00″N 89°38′30″E and 27°28′00″N 89° 38′30″E. The city is spread out laterally in a north-south direction on the west bank of the valley formed by Wang Chuu with an altitudinal range of 2,248 meters to 2,648 meters. The city stretches 15 km long & 3 km wide which starts from Dechencholing from the North and ends at Babesa in the South with the area of 26 Sq.km. Thimphu, as the political and economic center of Bhutan, contributes to 45% of the country’s GNP (Gross National Product). Thimphu contains most of the important political buildings in Bhutan, including the National Assembly of the parliamentary democracy and the official residence of the Kings. As a metropolis and capital city, Thimphu is coordinated by the “Thimphu Structure Plan”, an Urban Development Plan which evolved in 1998 intending to protect the fragile ecology of the valley.

Thimphu Thromde is further divided into 7 demkhongs namely: Babesa, Changbangdu-Olokha, Changangkha, Dechencholing, Jungshina- Kawajangsa, Motithang and Norzin as shown in Figure 1 above.

Figure 1: Bhutan Map Showing Study Area.

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Storm water challenges in Thimphu Thromde

Stormwater management in Thimphu city has been a major problem in recent years due to rapid development. The drainage system in Thimphu has been causing inconveniences to the residents and has become a major concern to the authorities. Every monsoon, city is faced with problems related to stormwater drainage which ranges from water overflowing from the drains, stagnating on the road and flowing into basement floors of buildings, causing inconveniences to people living it the city and damages to properties. The damages caused have increased over the years. During the Copenhagen Climate Change Conference of 2009 Thimphu has been recognized as one of the vulnerable cities to the Climate Change risk. The causes of drainage problems are of many dimensions. The human habits, rapid development, lack of Stormwater Drainage Management Plan leading to haphazard construction of drainages ad-hoc, etc. Some of the problems identified during the site visit by Flood Engineering and Management Division staffs are:

• No collector drains (Roadside drains) to the main drain mainly in the expressway. • BPC and Water Supply Pipes in Drains cause blockage during monsoon which leads

to the flow of water into the street. • Poor inlet in closed drains leading to poor usage of closed drains to convey

stormwater. • Poor Interlink between drains is one of the major problems observed during the site

visit. • Some drains are at a higher elevation than roads. • Household waste dumped in drains is a major problem in most of the drains. The

waste blocks drainage flow during monsoon leading to the flow of water into the street.

• No proper drains constructed in some parts of the city leading to the creation of Marshy area.

• Some drains were fully covered with grasses. Poor cleanliness and maintenance are observed during the site visit.

• Poor or no drain at road intersections. Drainage ends at road intersection leading to discharge of stormwater into the street.

• Inadequate drainage slope in some flat areas. (Centenary vegetable market & Thimphu Dzongkhag office)

• Some cross drainage sections are inadequate. Some larger drains are discharged into smaller drains leading overflow of drains.

• In new construction areas drainage was blocked by mudflow during monsoon. • Sewer overflow and blockage leading to street flooding is also a major problem in the

city, especially during monsoon.

The following figure below (Figure 2 to Figure 7) shows some of the stormwater management problems in Thimphu Thromde observed during the site visit.

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Figure 2: Poor drainage leading to Urban flooding (Near Immigration Office, Norzin lam)

Figure 3: : lack of proper drains lead to discharge of stormwater into street (-Near Tashi Taj)

Figure 4: Drain overflows, runoff discharged on road. (-Near Swimming pool roundabout).

Figure 5: Drainage blocked lead to discharge of stormwater into the street. (Near Thimphu Dzongkhag office).

Figure 6: Runoff from roads and drains is discharged into the street. (Below changadephu and Buddha point junction).

Figure 7: : Household waste dumped into drainage leading blockages(Near Financial Institutions Training Institute Ltd. (FITI))

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Goal and objectives of the assignment Goal

To assess and design sustainable, economical and environmentally sound stormwater management system that minimizes the potential threats of urban flooding and protecting natural drainage features.

Objectives • Assess for existing drainage system using SWMM, check for adequacy of existing and

recommend possible solutions. • Meet all applicable international and national regulatory requirements for stormwater

management system • Maintain existing stormwater management infrastructure and provide sufficient

infrastructure capacity to meet the future needs of the Thimphu Thromde. • Protect the natural drains and streams in the study area. • Implement sustainable stormwater management practices incorporating Low Impact

Development techniques where physically, economically, and practically possible.

Scope of Work The Scope of this Study is to assess, design drainage network with recommended solution or set of solutions for Thimphu Thromde with an area of 26 sq.km.

Available Data Digital Elevation Model (DEM)

The following Digital Elevation Models (DEMs) are available for the study area. Moreover, 2m contour is also available for Thimphu Thromde if required.

Table 1: Digital Elevation Model (DEM) available in study area.

Sl.No Items Data Source Original cell size 1 SRTM30 SRTM 30m grid square 2 ALOS DEM NCHM 10m grid square 3 Thimphu tiff.( Tagged

Image File Format) Thimphu Thromde 5m grid square

Meteorological Data (Rainfall, Maximum Temperature, Minimum Temperature and Relative Humidity)

There are 4 meteorological stations available in the watershed study area. All the data have a temporal scale of daily data interval except for Bjeemina station which has hourly data. The data availability varies from each station as shown in the table below.

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Table 2: Available meteorological station data.

Sl.No Station Name Data Available Data Interval Data Period 1 Begana Precp, Tmax,

Tmin, RH Daily 2008- 2018

2 MoEA Complex Precp, Tmax, Tmin, RH

Daily 2008- 2018

3 Simtokha Precp, Tmax, Tmin, RH

Daily 1996- 2017

4 Bjeemina AWS Precp, Tmax, Tmin, RH

Hourly Sept 2016 – June 2019

Figure 8: Location of Meteorological and Hydrology stations in study area.

Hydrology Data

The following hydrology data are available in study area.

Table 3: Available Hydrology data

Sl.No River or Stream Data Available Data interval Data Period 1 Thimchu Discharge Daily 2005- 2018 2 Samtellingchhu Low flow discharge Spot Discharge 2001- 2019 3 Olarongchhu Low flow discharge Spot Discharge 1993- 2019 4 Chubachhu Low flow discharge Spot Discharge 1994-2004

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5 DechephuChhu Low flow discharge Spot Discharge 2007-2019 6 Taba rongchhu Low flow discharge Spot Discharge 2007- 2019

Digitized drainage network of Thimphu Thromde

A total of 524 drainage attributes were collected during the site visit. The attributes include drainage cross-sections, type, construction material, and alignment. The following observations were made from the collected attributes: There are 119 primary drains and 405 secondary drains. Most of the drains are open (394). Generally, they are rectangular (279) and L-shaped (145). Materials of construction are mainly Stonemasonry (278) and Plain cement concrete (172) with or without RCC Slab covering. The report is also available with FEMD if required.

Figure 9: Digitized drainage network of Thimphu Thromde

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Plot boundary shapefile and other shapefiles

Plot boundary and current land use shapefile as of May 2019 is also available with Thimphu Thromde.

Details of task to be performed

Task A: Inception report

1. Review of relevant national and international literature, reports, future urban development plan, previous Stormwater Management Plan (if any), information on past initiatives and guidelines relevant to Stormwater Management Plan to understand the considerations, uncertainties, existing knowledge base, process and lesson learned for the Stormwater Management Plan preparation of Thimphu Thromde.

2. Review collected stormwater-network related data like cross section, alignment, type and slope of the existing stormwater network (both closed conduit or open channel and natural canals), location and dimension of any cross drainage and cross-check the data for maintaining consistency with help of the client.

3. Review Maps prepared by client of the surveyed existing stormwater network (both artificial and natural) using ArcGIS software on a suitable and representative scale with help of the client.

4. Collect available data on rainfall, glacier melt or snow, discharge of natural canals from established gauges in and around the project area and respective hydrological system with the help of the client.

5. Collect the most recent Digital Elevation Model and entire stream network of the project area with the help of the client and analyse topography of the area.

6. Identification of problems and opportunities in the existing stormwater management system.

Task B: An Interim report

1. Assessment of existing stormwater network through the identification of problems or critical portion of the network and analysing existing level of service and performance of the network.

2. Downscaling of climate data and analyse them to understand future climate change scenarios for the project area.

3. Delineation of the watershed area using ArcGIS tool from client provided DEM, stream network, inlet, and outlet point.

4. Frequency analysis of hydro-meteorological data and for design storm event selection. For the selection of design storm event also consider suitable national or international guideline for stormwater management.

5. Development of the SWMM model for the existing stormwater network in the project area, calibrate and validate it and then simulate for both present and future condition. For present condition simulation should be performed for design storm events. Relevant data like future climate or land use data, household water disposal to storm drain should be

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used as input data for future condition simulation along with others. Stormwater management model can be developed using the SWMM model

6. Assessment of adequacy of the existing stormwater network for both present and future and recommend suitable interventions (both structural and non-structural) if not found adequate in any of the cases to enhance and strengthen the capacity of the existing stormwater network.

Task C: The Storm Management Plan report

1. Develop different alternatives by simulating it in SWMM model incorporating different recommended interventions and climate change and future urban development scenario.

2. Development of strategies on the basis of options analysis and identify preferred strategies for sustainable stormwater management.

3. Recommend a stormwater management program for the Thromde to implement that will meet the desired levels of service, targets for compliance with regulations and guidelines, and other future pressures.

4. Develop a strategy to proceed with the implementation phase of the Stormwater Management Plan including specific tasks, schedule, and goals that will enable informed decisions based on equity and fairness, efficiency, practicality, and environmental soundness.

5. Develop an Integrated Stormwater Management Plan that addresses current and future stormwater in the City.

Deliverables, time frame and location Deliverables

The Consultant shall prepare the following reports:

1. Inception report: Approach and Work plan (draft to be submitted one month after contract signature) including Task A.

2. An Interim report including SWMM Model, identification and prioritization of potential solutions and selection of most promising solution or set of solutions for stormwater management in Thimphu Thromde including Task B

3. The Stormwater Management Plan including detail design and cost estimation of selected solution or set of solutions remodelled SWMM Model using recommended solutions in Stormwater Management Plan, including Task C.

The reports, which shall be made available in English, will have a clear and concise executive summary (of maximum 5 pages). Detailed analyses, tables, maps, and drawings shall be included as annexes. The Consultant shall submit above-mentioned reports in 1 hard copy and an electronic copy. The reports (inception, interim and Stormwater Management Plan) will be discussed with FEMD, DES (MoWHS), and Thimphu Thromde before presented to all stakeholders prior to final submission for approval.

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Timeframe

The Project is expected to take 9 months from contract signature. One month after contract signature the Draft Inception Report should be submitted. The interim report should be submitted 4 months after the contract signature. The Draft Management plan should be submitted 8 months after contract signature and will be finalised 3 weeks after receipt of comments from the Steering Committee.

The following schedule is applicable to delivering the following reports:

Table 4: Schedule for deliverables

Report Due Date Knowledge transfer/ Workshop

No. of Days

Inception report Up to 4 weeks after contract signature

Inception Report Presentation

1

Interim report Up to 4 months after contract signature

Interim report presentation

1

Knowledge transfer

3

Draft Stormwater Management Plan

Up to 8 months after contract signature

SWMP presentation

1

Knowledge transfer

3

Final Stormwater Management Plan

3 weeks after receipt comments from the Steering Committee

Note: consultant must bear Expert fees, travel, and accommodation. Client will pay for participants TADA, working Lunch, tea and snacks and conference hall charges only.

1. Location for service delivery

The assignment will be conducted both at the premises of the consultant and the premises of FEMD. The Consultant should specify missions to Bhutan and estimate the required budget also as part of the incidental expenditures. Office space in Bhutan will be provided by FEMD, DES, MoWHS for a reasonable number of experts (3-4).

Management and contribution of counterpart

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The Formulation Phase and the Implementation Phase of the foreseen studies and projects will be under the responsibility of a multi sector committee. The program shall be managed and monitored by two level of committee, Program Steering Committee (PSC) and Task Force Committee (TFC).

Composition of the Program Steering Committee (PSC)

1. Dasho Thrompon/Executive Secretary, Thimphu Thromde 2. Director, DES, MoWHS 3. Chief, FEMD, DES, MoWHS 4. Chief , Infrastructure Division, Thimphu Thromde 5. Chief, Environmental Division, Thimphu Thromde

Roles and Responsibilities of PSC

i. Meet twice during the project duration. ii. Review and endorse the final report submitted by the Task Force Member iii. Review any issues related to the project and provide necessary directives iv. Make any decisions related to the project v. Endorse Work Plan of the project

Composition of the Task Force Committee (TFC)

1. Mr. Kedhar Kumar Adhikari, GIS Officer, FEMD, DES, MoWHS (Project Manager) 2. Ms. Jangchuk Choden, Infrastructure Division, Thimphu Thromde 3. Mr. Ngawang Tashi, Infrastructure Division, Thimphu Thromde 4. Ms. Dhendup Lhamo, Infrastructure Division, Thimphu Thromde 5. Mr. Roshan Rai, Urban Planning Division, Thimphu Thromde 6. Mr. Tshering Tashi, Exe. Engineer,FEMD,DES,MoWHS 7. Mr. Ugyen Phuntsho, Engineer, FEMD, DES, MoWHS 8. Ms. Dorji Wangmo, Engineer, FEMD, DES, MoWHS

General roles and responsibility of TFC

i. Develop and finalize the Terms of Reference (ToR) for the program. ii. Assist the Consultant in providing required information on behalf of their respective

agency. iii. Arrange office space and required equipment’s for Consultant if required. iv. Arrange every consultation of Expert with relevant agency. v. Make available to meet quarterly and as and when required.

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Specific responsibilities of TFC members

Table 5: Responsibilities of Task Force Committee.

FEMD, DES,

MoWHS`

Liaise with the Thimphu Thromde on project matters ✓ Lead in drafting of ToR for the study ✓ Data compilation from relevant stakeholders ✓ Provide working space and technical backstopping to the

Consultant

Thimphu Thromde Liaise with the FEMD on project matters Lead in implementation of Management Plan Provide technical backstopping to the Consultant

Communication

The Consultant is required to consult relevant stakeholders in all phases of the study as and when required. The Consultant shall consult the following institutions (at minimum) during the course of his/her work:

- Flood Engineering and Management Division, DES, MoWHS - Thimphu Thromde - National Centre for Hydrology and Meteorology (NCHM) - National Environment Commission (NEC)

Personnel

The qualification requirements for the services to be delivered are provided below. The personnel assignment schedule shall be coherent with the work plan (activity schedule) and with the number of man-months which will be reflected in the cost breakdown of the financial proposal. The team of key personnel shall comprise at least the competences/functions mentioned below. However, the total number of key experts (which will be considered for bid evaluation) shall not exceed five. The bidders shall submit CV´s of the key experts.

Team leader The team lead should have Master’s Degree in hydrology/ water resource management or any other relevant qualification. The team leader is the key senior expert, predominantly responsible for the smooth implementation and effective performance of the overall services, for the coordination and timely performance of all activities and missions by the associated partners of the Consultant (management of interfaces). Moreover, he is responsible for communication on site with the client for the organisation of the workshops, for the elaboration and timely

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submission of deliverables and for quality control of the services and the reports. Hence, the team leader shall dispose of corresponding project management experience and of respective credentials. Next to project management the team leader will be involved as a key expert in a number of the tasks requested.

Other experts The following fields of expertise (see table below) are expected to be covered by senior and supporting experts in the team. The senior experts are assumed to work closely with the team leader. One expert may cover several of these fields.

Table 6: Description of specific field of expertise required.

Expertise field Specific expertise Local/International Stormwater Management Expertise

• Minimum of Master Degree in hydrology/ water resource management or any other relevant qualification

• Have completed at least one similar study within the last five years in another municipality/cities, preferably in Southeast Asia and demonstrate an understanding of and insights in sustainable storm water Management

• Experience in Formulation of Stormwater Management Plan Local/International Stormwater Modelling (EPA SWMM) expertise

• Minimum of Bachelor’s Degree in Civil Engineering • At least 2 years’ experience in Modelling Stormwater using

(EPA SWMM) • Have technical excellence and innovation in the field of

municipal engineering including, stormwater management and regulations, operations and maintenance, mapping, and geographic information systems.

Local/International Designing, Drawing and estimation Expert

● At least 3 years’ experience in Designing, Drawing and estimation of structural and non- structural stormwater management structures.

● Minimum of Bachelor’s Degree in Civil Engineering

Reporting

The consultant will report to the Chief Engineer, Flood Engineering and Management Division,

Department of Engineering Services, Ministry of Works and Human Settlement.

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