Assessment and planning of the water resources Assessment and planning of the water resources under various scenarios in the Ganges and Indus under various scenarios in the Ganges and Indus basin: Glaciers contribution and WEAP modellingbasin: Glaciers contribution and WEAP modelling

Devaraj de CONDAPPAMarisa ESCOBAR

Luna BHARATIPriyantha JAYAKODY

Stockholm Environment Institute International Water Management Institute

CPWF Basin Focal Project for the IG BasinCPWF Basin Focal Project for the IG Basin

2 - 3 December 2009, New Delhi2 - 3 December 2009, New Delhi

Mac Kirby [Eastham et al. (2008)] gave an overview of hydrological water uses in the IG Basin.

Objective here: develop an application of the Water Evaluation And Planning (WEAP) in the Indus and Ganges basin so as to:• assess the water resources, in particular contribution from

glaciers,• model its utilisation / planning,• and provide insight into some possible future scenarios.

Outline of the presentation:1. Brief introduction to WEAP.2. Input data gathered.3. Setting WEAP in the Indus and Ganges.4. Analysis of simulations:

• current situation,• scenarios.

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Objective

Water Evaluation and Planning (WEAP)

Developed by the Stockholm Environment Institute (SEI). Models simultaneously:

• hydrology: the water resources,• planning: uses of these resources.

Hydrology:• model rainfall / runoff: based on

landuse; soil parameters.

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Water Evaluation and Planning (WEAP) Hydrology:

• glaciers module: models variation in glaciers area, streamflows, based on degree-day approach, i.e., streamflow calculated with the

potential

sub-division of acatchment:

aice or snow⋅T −T 0degree day factor for ice or snow

(mm/°C/day)

rain / snow temperaturethreshold (°C)

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Input data gathered

Climate: the TS 2.1 dataset from the Climate Research Unit (CRU).

Observed streamflows:• International databases;• IWMI: Upper Kosi (Nepalese part) and Upper Ganges;• some time series in the Indus extracted from the spreadsheet

of Eastham et al. (2008);• average annual trends from Jain et al. (2007) in the Ganges.

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Input data gathered

Observed streamflows:

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Modelling units: sub-basins

Generation of sub-basins with respect to:• available observed time series of streamflows,• large reservoirs or barrages,• major river outlets (where some average annual flows were

available).

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

WEAP-Indus and WEAP-Ganges

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

WEAP-Indus down to Kotri

WEAP-Ganges down to Farakka

Hydrological objects

Water demands

WEAP-Ganges

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Reliability of WEAP-Indus & WEAP-Ganges

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Reliability of WEAP-Indus & WEAP-Ganges

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Calibration

Validation

CalibrationCalibration

Reliability of WEAP-Indus & WEAP-Ganges

What can these WEAP applications simulate?

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Analysis current situation: water uses

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

In the Ganges Adapted from Amarasinghe et al. (2007)• For year 2000

In the Indus:• Adapted from Amarasinghe et al. (2007) and Habib (2004)• lumped demand for the Indus Basin Irrigation System• For year 2000

Analysis current situation: impacts of canals

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

In the Indus

Average annual streamflows, simulated for period 1982 - 2002

In the Ganges

Analysis current situation: impacts of canals

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

In the Ganges, HaridwarUpper Ganga canal

In the Ganges, NaroraMadhya & Lower Ganga canals

In the Ganges, TajewalaWestern & Eastern Yamuna canals

Average monthly streamflows, simulated for period 1982 - 2002

Analysis current situation: contribution from glaciers

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

HaridwarBefore canal Haridwar

After canal

Average streamflows simulated for period1982 - 2002

Farakka

Analysis current situation: contribution from glaciers

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

DanyourBridge

Tarbela dam

Sukkur

Indus heavily depend on contribution from glaciers

Tarbeladam Sukkur

Scenario analysis: increase in temperature

According to the IPCC: temperature +3.8 °C at the end of the century in the Tibetan region.

Same order by ICIMOD. considered 3 scenarios for 20 years:

• +1°C after 20-years, i.e., a rate of +0.05°C/year,• +2°C after 20-years, i.e., a rate of +0.10°C/year,• +3°C after 20-years, i.e., a rate of +0.15°C/year.

Compared to the reference scenario = period 1982 to 2002.

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Scenario analysis: increase in temperature

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Haridwar Devghats

Farakka

Risks of floods

Scenario analysis: increase in temperature

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Danyour BridgeTarbela dam

Sukkur Risks of floods

Scenario analysis: increase in temperature

Additional annual flow:

Additional flow mainly during the high flow season how to use it?

Tricky as high discharge. Maybe extra flows in April, May & June + September &

October?

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Ganges

Indus

Scenario analysis: reduction in initial glaciers

What could be consequences of a drastic reduction in glaciers coverage?

considered 4 scenarios for 20 years: initial decrease in glaciers coverage by 25, 50, 75 and 100%.

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Scenario analysis: reduction in initial glaciers

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Analysis scenario: reduction in initial glaciers

0. Outline 2. Input data 4. Current situation1. WEAP 3. Setting WEAP Scenarios

Devaraj de CONDAPPAdevaraj.de.condappa@googlemail.com