Scenario-Based Modelling Studies to Assess the Impact of Climate Change on Floods in the German Rhine Catchment

摘要

The aim of the study is to analyse the impact of global climate change on regional hydrology with special emphasis on discharge conditions and floods. The investigations are focussed on important sub-catchments in the German Rhine catchment where a chain of models was applied: Large scale atmospheric fields, simulated by two different Global Circulation Models (GCMs) driven by the emission scenario IS95a ('business as usual') were used as input to the method of expanded downscaling (EDS). EDS delivers local time series of scenario climate variables (precipiation, temperature) as input to HBV-D, a hydrological model that simulates runoff under present as well as scenario climate conditions. Observed and simulated time series of discharge were analysed in order to assess possible future runoff conditions under the impact of climate change. The study indicates a potential increase in mean runoff and flood discharge for small return intervals. However, the uncertainty range that originates from the application of the whole model chain and two different GCMs is high. This leads to high cumulative uncertainties, which do not allow conclusions to be drawn on the development of future extreme floods.