Selected precipitation scenarios across Europe

We report results of the project, European River Flood Occurrence and Total Risk Assessment System (EUROTAS), which was aimed at assessing the risk of current and future floodings for Europe, including the effects of climatic change. With respect to the latter, precipitation scenarios have been derived from a global climate model using the method of expanded downscaling (EDS), and regionalized for the catchment of the river Pinios (Greece). Jizera (Cechia), Saar (Germany), and Thames (UK). We present both the climate change information conveyed by the scenarios and an assessment about its statistical significance. For this report, all simulations were rerun using an improved EDS model version. Most notably, the inclusion of atmospheric humidity to the set of global predictor fields helped reducing the underlying uncertainty of the results. When driven by observed atmospheric fields (analyses), the EDS model performed in most cases satisfactorily, as it reproduced the larger precipitation clusters with good accuracy. To evaluate the precipitation scenarios, a statistical test was applied that compared what we defined as 'current climate' with the 'changed climate' of the scenario. To define current climate, local precipitation observations were used together with EDS regionalizations of the analyses and of a climate model control simulation. It turned out that in spite of the considerable uncertainty stemming from model errors and, more importantly, natural variability, a significant redistribution of rainfall is projected. Specifically, the scenarios show a decay of rainfall frequency for all catchments, which for Pinios leads to an overall negative water balance. This is accompanied, and for the other catchments outweighed, by a strong rainfall intensification. For the latter, we provide a more detailed extreme value analysis. We emphasize that the results should be interpreted with caution and not overemphasized quantitatively. Scenarios of precipitation are still of prototype nature and under steady development. (C) 2002 Elsevier Science B.V. All rights reserved.