Cover slide option 1 Title

Water Resources Development in the

Koshi Basin

Pennan Chinnasamy, Luna Bharati, Ambika

Khadka, Utsav Bhattari.p.Chinnasamy@cigar.org

Nepal Water WeekMarch 21, 2015

Photo: Hamish John Appleby / IWMI

INTRODUCTION

• IWMI

• IWMI Nepal

• Koshi basin

Taskent

WHY NEPAL?

• Nepal is one of the most water abundant countries in the world with total mean annual runoff of 224 billion cubic meters (BCM) and per capita water availability of 9,000 m3.

• There is large temporal and spatial variation in water availability. 85% of rainfall is during the four monsoon months (June-Sept.)

• Water resources remain a particularly under-developed sector –Nepal is currently only utilizing 7% of its annual water availability (14% in the Koshi Basin). 24% of arable land is irrigated and out of 43,000 MW hydropower potential, only 689 MW has been developed

• The impact of CC: what it means to future water availability and development.

• The general perception is that if this resource is properly harnessed, it would be the ticket out of poverty through economic growth mainly in the hydropower and agriculture sectors.

IWMI – NEPAL PROJECTS

•Basin level water

management

• Impact of Climate Change

in the basin level

•Water resources and

vulnerability assessments

for entire Nepal

Bharati 2015

KOSHI BASIN

Objectives for the Koshi Basin Analysis

• Resource assessment i.e. water availability vs. water use at sub-basin level (SWAT and WEAP)

• Impact of CC on river basin hydrology

• Future basin development scenarios – risks, vulnerabilities, opportunities

• Partners/Donors: ICIMOD, CIDA CSIRO, World Bank, WLE

KOSHI BASIN (CONTD…)

• Koshi Basin (87,311 km2): Transboundary basin-Largest contributor to the Ganges river

• The elevation of the basin varies from about 20m in the plains in India to more than 8,000 m in the Great Himalayan Range. Mount Everest (8,848 m) is also located in the basin.

• The basin in the Nepal part is undeveloped but there are plans to build multiple water infrastructure.

HYDROLOGICAL MODEL: SWAT

INPUT DATA

Spatial: topography – Digital elevation map

Land use map

Soil map

Climate data: Time series Rainfall

Min and max temperature

Relative Humidity

Solar Radiation

Wind Speed

Hydrological Cycle is based on following Water Balance Equation:

n

i

gwseepasurfdayot QwEQRSWSW1

)(

Where, SWt : Final soil water content (mm)SWo : Initial soil water content (mm)t : Time in daysRday : Amount of precipitation on day I (mm)Qsurf : Amount of surface runoff on day i (mm) Ea : Amount of evapotranspiration on day i (mm)wseep : Amount of percolation on day i (mm)Qgw : Amount of return flow on day i (mm)

KOSHI WATER BALANCE (1998-2008)

CC ANALYSISRCP4.5

RCP8.5

Water Resources Development in

the Koshi

• Water resource development in the Koshi basin• Need for water accounting model – WEAP• Water storage potential in the basin• Hydropower potential in the basin• Future water demands and how infrastructure

development can aid

Water use status (demand and supply) in the Koshi Basin

• Collection of district level water use and demand data

• Estimate relationship between water use and demand

• Test against future climate change scenarios

• Aid in formulation of better management plans

Study DefinitionSpatial Boundary System Components

Time Horizon Network Configuration

EvaluationWater Sufficiency Ecosystem Requirements

Pollutant Loadings Sensitivity Analysis

Current AccountsDemand Pollutant Generation

Reservoir Characteristics Resources and Supplies

River Simulation Wastewater Treatment

ScenariosDemographic and Economic Activity

Patterns of Water Use, Pollution Generation

Water System Infrastructure

Hydropower

Allocation, Pricing and Environmental Policy

Component Costs

Hydrology

WEAP

Structure

Results for 2000 baseline year and future Scenarios

Koshi Basin Water Supply Estimates• Spatial Variations• Temporal Variations

Water Demands in the basin• Spatial Variations• Temporal Variations• Sectoral Demands

Subbasin level annual average water demand for the Baseline Scenario.

Water Demands in the basin• Spatial Variations• Temporal Variations• Sectoral Demands

Subbasin level annual average water unmet demand for the Baseline Scenario.

Koshi Basin Water Resource Development

• Based on JICA (1985, 2014)

• 7 Run of the River Type• 4 Storage type• High capacity

• Sapta Koshi • Sun Koshi

www.iwmi.org

Water for a food-secure world

Results

Project Type

Available

Storage

(MCM)

Hydropower Generation (GWh)

Winter Pre-

monsoon Monsoon

Post-

monsoon Annual

Arun III ROR - 8 33 60 8 109

Bhote Koshi ROR - 47 100 187 72 406

Lower Arun ROR - 364 524 695 348 1931

Sundarijal ROR - 27 61 113 21 222

Sun Koshi (HEP) ROR - 25 54 94 38 210

Tama Koshi ROR - 38 161 372 63 634

Upper Arun ROR - 169 279 451 225 1124

Dudh Koshi S 162 25 34 209 47 315

Sapta Koshi High

Dam S 4420 761 2375 10716 2695 16547

Sun Koshi S 3040 242 501 3627 784 5154

Tamor S 760 81 553 2189 258 3081

Total 8382 1787 4676 18712 4558 29733

* ROR = Run-Of the-River, S = Storage

Total water storage potential is 8382 MCM

Water demand under Baseline scenario with WRDs.

Demands and Flow Winter Pre-

monsoon Monsoon

Post-

monsoon Annual

Baseline

Flow (m3/s) 39 166 699 144 262

Domestic demand (MCM) 386 395 524 262 1566 (6 %)

Agricultural demand (MCM) 1890 6608 13489 2009 23996 (92 %)

Industrial demand (MCM) 105 107 142 71 424 (2 %)

Demand (MCM) 2380 7110 14154 2342 25986

Unmet demand (MCM) 273 370 0 17 660

* Brackets indicate percentage change from Baseline scenario. MCM- Million Cubic Meters

Past Current Future

Wat

er d

eman

d

Time

Current trend

Higher water availability

Lower water availability

Lower stress/growth

Higher stress/growth

Future Scenarios

Seasonal variations in water demand and unmet demand under baseline, water resources

development, population growth, agricultural growth and industrial growth scenarios.

Scenarios Winter

Pre-

monsoon Monsoon

Post-

monsoon Annual

Baseline

Demand (MCM) 2380 7110 14154 2342 25986

Unmet (MCM) 273 370 0 17 660

Population growth

Demand (MCM) 2727 9356 15521 2576 30180

Unmet (MCM) 337 555 0 27 920

Unmet Percent change (%) 23 50 0 60 39

Agricultural growth

Demand (MCM) 2406 8795 15215 2506 28922

Unmet (MCM) 370 543 0 58 970

Unmet Percent change (%) 36 47 0 241 47

Industrial growth

Demand (MCM) 2788 9419 15604 2618 30429

Unmet (MCM) 386 575 7 35 1003

Unmet Percent change (%) 41 55 0 106 52

* Unmet Percentage Change is the change in unmet demand between Baseline and Scenario.

Seasonal variations in water demand and unmet demand under baseline, water resources

development, population growth, agricultural growth and industrial growth scenarios.

Scenarios Winter

Pre-

monsoon Monsoon

Post-

monsoon Annual

Baseline

Demand (MCM) 2380 7110 14154 2342 25986

Unmet (MCM) 273 370 0 17 660

Population growth

Demand (MCM) 2727 9356 15521 2576 30180

Unmet (MCM) 337 555 0 27 920

Unmet Percent change (%) 23 50 0 60 39

Agricultural growth

Demand (MCM) 2406 8795 15215 2506 28922

Unmet (MCM) 370 543 0 58 970

Unmet Percent change (%) 36 47 0 241 47

Industrial growth

Demand (MCM) 2788 9419 15604 2618 30429

Unmet (MCM) 386 575 7 35 1003

Unmet Percent change (%) 41 55 0 106 52

* Unmet Percentage Change is the change in unmet demand between Baseline and Scenario.

Total water storage

potential is 8382 MCM !

0

500

1000

1500

2000

2500

3000

3500

4000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Peak

Lo

ad (

MW

)

Ener

gy (

GW

h)

year

Energy (GWh)

System Peak Load(MW)

0

500

1000

1500

2000

2500

3000

3500

4000

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Peak

Lo

ad (

MW

)

Ener

gy (

GW

h)

year

Energy (GWh)

System Peak Load(MW)

Total Hydropower generation is 29000 GWh

www.iwmi.org

A water-secure world

Total annual volume of water flowing into India = 57405 MCM

Total annual volume of water flowing into India = 55138 MCM

Base Case : Year 2000 Case 1: Irrigated area = Irrigable area

Case 2: Hydropower generation + E-flows (B)Total annual volume of water flowing into India = 56837 MCM

www.iwmi.org

Water for a food-secure world

Conclusion• Study provides first estimates of sectoral water demands and unmet demands for

the basin.• Study provides first estimates of the water storage and hydropower generation

potential for the basin.• Water resource developments can ease climate vulnerability, water availability

issues and future water demands.• Water resource developments can have huge hydropower generation potential

• Ease current and future National power shortage • Enable economic growth by trans-boundary power sharing agreements• Industrial developments