Suchergebnisse

Abstract. Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study a conceptual hydrological model was forced by downscaled and bias-corrected outcome from three general circulation models for the SRES A2 emission scenario (GCM forced models), and the WATCH Forcing Data set (reference model). The threshold level method was applied to investigate drought occurrence, duration and severity. Results for the control period (1971–2000) show that the drought characteristics of each GCM forced model reasonably agree with the reference model for most of the climate types, suggesting that the climate models' results after post-processing produce realistic outcomes for global drought analyses. For the near future (2021–2050) and far future (2071–2100) the GCM forced models show a decrease in drought occurrence for all major climates around the world and increase of both average drought duration and deficit volume of the remaining drought events. The largest decrease in hydrological drought occurrence is expected in cold (D) climates where global warming results in a decreased length of the snow season and an increased precipitation. In the dry (B) climates the smallest decrease in drought occurrence is expected to occur, which probably will lead to even more severe water scarcity. However, in the extreme climate regions (desert and polar), the drought analysis for the control period showed that projections of hydrological drought characteristics are most uncertain. On a global scale the increase in hydrological drought duration and severity in multiple regions will lead to a higher impact of drought events, which should motivate water resource managers to timely anticipate the increased risk of more severe drought in groundwater and streamflow and to design pro-active measures.

The EU-FP7 XEROCHORE project is a Support Action (SA) that for the first time brings together three interrelated drought aspects at the European scale, namely (1) the natural system (climate and hydrological systems), (2) impacts (socio-economic and environmental), and (3) drought management and policy. It compiles a roadmap that includes the state-of-the-art and identifies research gaps in these three aspects. Moreover, it provides guidance on appropriate responses for stakeholders. XEROCHORE's outcome contributes toward a future European Drought Policy, in accordance with the EU-Water Framework Directive (WFD) and other related EU legislation and actions.