Modelling water availability and water allocation strategies in the Scheldt basin. Sub report 4-5. Analyses of hydrological models for climate change modelling – WETSPA

The water balance model of the Scheldt basin will be used in order to perform low flow forecasts and calculate climate change scenarios. Within the current subtask is investigated which is the most appropriate hydrological model for the sub catchments of the water balance model of the Scheldt basin in order to meet this prerequisite. This sub report describes the evaluation of WETSPA models (Water and energy transfer between Soil plant and atmosphere, Salvadore, E. et al., 2012, 2021). Hydrological models with WETSPA are developed for the sub catchments included in the water balance model (including the Meuse basin). To assess the water availability and the flow behavior, each catchment was calibrated manually to find an optimal parameter set. The optimization during calibration is performed based on an automatic procedure followed by a visual control. During the optimization routine the parameters set is selected based on 2 criteria: (1) absolute error on cumulated total flow at each time step, and (2) logarithmic Nash-Sutcliff efficiency. The first criterion aims to model the global flow pattern, the latter focuses mainly on the low flows. In general the simulation of the hydrology of the Scheldt and the Meuse basin gives from reasonable to fairly good results and by consequence the developed hydrological models could be used to predict the future water availability under climate change.