Description:
The majority of hydrologic and hydraulic models contain many important uncertainties due to, amongst others, two important shortcomings; large-scale input resolution (of hydrological models) and limited feedback with the atmosphere. A new model system was designed which will be applied for flooding assessments and which will also address these shortcomings. The system consists of RAMS (regional atmospheric model) coupled to the hydrological model (VIC).
Research objectives:
The objectives are:
1. To develop new cross boundary adaptation strategies to mitigate extreme events (floods and droughts) in the Rhine basin under climate change. The strategies are designed to enhance the adaptive capacity in water management for both the Netherlands and Germany.
2. To develop a coupled atmospheric-hydrological model describing both the energy and water balance for the whole Rhine basin. The model enables simulating adaptations related to land use changes and provides accurate information on the timing of extreme events. The latter though enhanced simulation of soil moisture conditions and a more appropriate description of the land surface atmosphere exchanges and possible feedbacks.
Results and products:
The use of the coupled model (WAMMS - Wageningen Atmosphere Mesoscale Modelling System) was demonstrated for a historical flooding event in the Rhine river basin, together with results of an analysis applying different model resolutions (see figure 1, where the effect of resolution on precipitation fields is clearly demonstrated). It was shown that using RAMS output as forcing data for VIC results in better predictions of the timing of peak events than large-scale climatological data (REMO). The coupled model is sensitive to initial conditions and parameter settings. Therefore, an intensive calibration mechanism has been set up to create a realistic set of parameters. This led to improved simulations of the discharge simulated for Lobith (see figure 2). An important mechanism, while using WAMMS, is that a well-thought bias correction needs to be applied to the input data for future studies.
We also assessed the impact of land use change scenarios and climate change scenarios for the Rhine basin using the VIC model as applied and calibrated previously. Areas that are sensitive to land use changes, and precipitation events leading to extreme streamflow can now be identified for modeling with WAMMS. |
