1. EC Workshop on European Water Scenarios Brussels 30 June 2003
The WaterGAP Model: A Tool for European-scale Water Assessment & Scenarios
EC Workshop on European Water Scenarios Brussels 30 June 2003
Joseph Alcamo Center for Environmental Systems Research University of Kassel, Germany

2. Developing European Water Scenarios A Multi-scale Analysis
European Modeling
European Scenarios
Data for validation
Process parameterization
Boundary
conditions
River basin detail
Boundary
conditions
Regional/River Basin
Modeling
Regional Scenarios

3. WaterGAP - Overview - Water Availability Watershed Water Stress Water
(by 0.5° grid-cell)
Runoff
Recharge
Land Cover
Climate
Water Availability
Watershed
Water Stress
Population
Income
Technology
Climate
Water
Use
Water Withdrawals
Domestic (by country)
Industrial (by country)
Irrigation (by grid-cell)
Livestock (by grid-cell)

4. WaterGAP - Overview -
Hydrologic Resolution: 0.5° x 0.5° grid-cell, river basin
Water Use Resolution: Domestic/Industry: country, downscaled to grid. Irrigation: grid-scale
Applications:
World Water Commission, World Water Vision Scenarios
UNESCO et al World Water Assessment Programme
World Water Council, et al, Dialogue on Water & Climate
UNEP, Global Environmental Outlook 3
German Research Ministry, Eurowasser

5. WaterGAP - Water Availability Model -
Land Cover (Albedo)
Cloudiness
Temperature
Potential
Evapotranspiration
Actual Evapotranspiration
Maximum Soil Water Content
Land Cover
(Rooting Depth) - +
Rain & Snowmelt
SOIL WATER
BALANCE -
Surface Runoff
& Groundwater Recharge
Slope
Texture

6. Calibration of WaterGAP Kymijoki River at Station Anjala (36.000 km²)

7. Testing/Calibrating WaterGAP
Note: all graphs with seasonal
regimes show specific discharge
in mm/month derived from
time series

8. WaterGAP - Water Use Model -
Domestic Water Use
Population
Income
Electricity
Water Intensity
Industrial
Water Use
Irrigated Area
Cropping Intensity
Livestock Intensity
Water Use Efficiency
Climate
Irrigation
(+Livestock) Water Use

9. WaterGAP - Water Use Model : Domestic -
Water Intensity
Water Intensity
Domestic
Domestic
Today
Income
Time
Structural Change
(changing behaviour and infrastructure)
Technological Change
(improving water use efficiency)
Water Intensity
Domestic
Income & Time
Structural & Technological Change
The Hague, March 2000 (TH)

10. WaterGAP - Water Use Model : Irrigation -
Crop-Specific Evapo-
transpiration
Precipitation
Irrigated Area
Cropping Intensity
Soil Characteristics
Temperature
Precipitation
Cropping Patterns
Growing Season - +
Net Irrigation
Requirements
Irrigation Efficiency
(field efficiency)
Irrigation
Water Withdrawals
- per 0.5° grid-cell -

11. Example Scenario Analysis:
What are trends in future water use? Baseline scenario to 2075 Source: “EuroWasser” Study, German Ministry of Research
Domestic
Irrigation
Industry
Total

12. Example Scenario Analysis: What are impacts on water stress of latest IPCC climate change scenarios? Source: Dialogue on Climate and Water, World Water Council, et al
IPCC Scenarios

14. A2 Scenario
Higher population growth
Lower level of water conservation
Faster climate change

15. B2 Scenario
Lower population growth
Higher level of water conservation
Slower climate change

16. Using Models for Scenario Analysis -- Many Uncertainties

17. EuroWater - GCMs Combination of Maps -
Uncertainty of Water Availability due to Climate Inputs (WaterGAP Calculations using data from 2 Climate Models)
EuroWater - GCMs Combination of Maps -
2070s
Based on HadCM3
2070s
Comparison
2070s
Based on ECHAM4
Change in Availability
Both GCMs
Decrease
No Change in Both
Both
Increase
Contradict

18. Using Models for Scenario Analysis --- Many Uncertainties
Different climate scenarios.
Disagreement among climate models for same scenario.
Inaccurate regional/river basin climate.
Inaccurate fine-scale hydrology  seasonality, year-to-year variability, storage, routing.
Inaccurate water use data on country and finer scale.
Uncertain relationship between driving forces (income, water prices, water rights, others ....) and water use.

19. WaterGAP Model for 3 Water Topics
WaterGAP can provide European perspective for 3 major water topics:
Water Scenarios (II.4) – Tool for developing European-scale, long-term scenarios; assembling necessary driving force data.
Integrated WR Mangement (II.3.1.b) – Tool for assembling European-scale spatially-detailed data on water use, water availability, driving forces. Tool for assessing current European/transboundary situation.
Water Stress (II.3.3.b) – Tool for calculating water stress on European-scale with spatial detail. Tool for assembling data for water stress, and for testing different water stress indicators.

20. Challenges & Conclusions
For European assessment & scenarios, need multi-scale analysis  European-scale models are necessary tools.
Couple/harmonize European models with regional/river basin models.
Need to address uncertainties of models  Increase knowledge base.
Improved water use data and simulation
Improved hydrologic data and simulation
Improved understanding of role of different driving forces (income, water prices, institutions, ...)

21. EC Workshop on European Water Scenarios Brussels 30 June 2003
The WaterGAP Model: A Tool for European-scale Water Assessment & Scenarios
EC Workshop on European Water Scenarios Brussels 30 June 2003
Joseph Alcamo Center for Environmental Systems Research University of Kassel, Germany