Center for Environmental Systems Research - University of Kassel Possible impacts of climate change on water availability – sensitivity anlysis and response surfaces M. Weiß and J. Alcamo

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki WaterGAP -overview- Physiograhic, socio-economic and climate data to model globally current and future water availability and water uses The hydrological model calculates daily water balances on a 0.5 x 0.5 degrees grid call basis The water use model calculates water withdrawals for the different sectors household, industry (manufacturing and electricity production) and agriculture (livestock and irrigation). By comparison of water availability and water use we can calculate various water stress factors on a river basin scale

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Sensitivity analysis and response surfaces The European continent is covered by more than 6000 cells at a typical size of about 35 km to 55 km (depending on latitude) 18 case study river basins selected

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations Sensitivity analysis I based on the climate averages (CRU, New et al., 2000) changes in longterm annual temperature averages (-5°C - +5°C) and longterm annual precipitation averages (-50% %) preliminary analysis of changes in the longterm average river discharge preliminary analysis of changes in the longterm average yearly flow regime (monthly mean discharges) first studies on impact thresholds

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharges SA I

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharges

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharges dT=+5°C=const dT=0°C=const dP=+100%=const dP=0%=const

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharges

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharges dT=+5°C=const dT=0°C=const dP=+100%=const dP=0%=const

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki In their response, the river basins can be divided into the three groups: northern, central, and southern European basins Fig.: RS for northern, central, southern European catchments Guadalquivir (Southern Europe) Danube (Central Europe) Lule (Northern Europe) Response of water availability to climate variations annual variation, longterm average discharges

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm monthly mean discharges

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Threshold studies competitive uses a) within society itself, i.e. the different sectors b) society vs. environment. various operational thresholds, e.g. minimum flows for hydropower Envrionmental flow, e.g. thresholds based on technical guidance from the EU Water Framework Directive water stress indicators return intervalls of extremes, e.g. drought frequencies Thresholds are sector-, region- and system-dependent global water studies

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations Sensitivity analysis II based on the climate averages (CRU TS 2.1, Mitchell and Jones, 2005) changes in longterm seasonal temperature averages (JJA) (-3°C - +3°C) and longterm seasonal precipitation averages (JJA) (-50% - +50%) preliminary analysis of changes the longterm mean summer river discharge

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations seasonal variation, longterm average discharges SA II (JJA)

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Perturbed Physics Experiment

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharge

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Response of water availability to climate variations annual variation, longterm average discharge

M. Weiß and J. Alcamo WP 6.2 meeting, Helsinki Points of discussion relationship between annual and seasonal climate changes coupling function Interpolation of climate information probabilities