Model based estimation of climate change impacts on the drainage demand of low lying coastal areas in Northwest Germany along the North Sea

Abstract

Study regionThe Northwest German part of the North Sea coast Study focusLow lying coastal areas are highly threatened by climate change. This is due to rising sea level and changing water balance caused by climate change. Adaptation of coastal protection and inland drainage to climate change requires precise predictions of future conditions. While information on sea level rise is globally available, coastal water balance projections need to be specific for regions where often no discharge data is available. To serve this demand, a model based scenario analysis was carried out for four water boards in Northwest Germany. These water boards are regional organisations responsible for drainage and surface water level regulation in marsh areas. A water balance model was calibrated and validated against data of pumping stations and tidal water gates. Subsequently, climate change impacts on runoff generation were estimated. New hydrological insights for the regionThe results indicate that runoff generation is expected to increase significantly in the wet season, same as the frequency of periods with large runoff volumes. The climate change impact signal is consistent over all investigated water board areas, indicating that the climate change signal dominates the spatial variability in soil properties and land use. The results emphasize the necessity to consider runoff generation projections for adjusting coastal drainage management. The scenario projections can be directly used for regional adaptation planning processes, taking into account the underlying uncertainties.