CHC-FloodS

Abstract:

The project aims at developing a coupled climate/hydrology modelling system on catchment scale to provide a meaningful tool for analysing climate change effects on the water balance, especially on flash floods. Results from highly resolved regional climate models (RCMs) are evaluated with respect to their ability to capture main triggering mechanisms for flash floods in Styria. Regional climate model output data is used to drive a hydrological model in order to analyse simulated time series of river discharges with respect to certain flooding events. The evaluation of the coupled modelling system is focused on certain criteria (e.g. weather pattern, seasonality, etc.), which are derived from observed flash flood events, but also on the spatial resolution of the RCMs (50 km, 12.5 km, and 3 km grid spacing) as well as on the effect of implementing a proper bias correction technique for the RCM output. The study uses a small multi-model-ensemble which consists of two RCMs that are driven by re-analysis data (period 1989 to 2010). For testing purposes, the modelling system including bias correction is employed based on climate simulation on convection permitting scale (3 km grid spacing). As testing area the southern parts of Styria are used, because local heavy precipitation events are often leading to flash floods in that region. From the project conclusions about the benefit of convection permitting climate simulations as well as the demands of hydrology on climate models, especially for bridging the gap in scales between those two model families, are drawn.