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

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

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)

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

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

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

Testing/Calibrating WaterGAP Note: all graphs with seasonal regimes show specific discharge in mm/month derived from time series 1961-90

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

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)

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 -

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

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

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

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

Using Models for Scenario Analysis -- Many Uncertainties

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

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.

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.

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, ...)

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