Assessing the impact of resolution and soil datasets on flash-flood modelling

Abstract. The present study assesses the impacts of two grid resolutions and the descriptors of soil texture and land cover on flash-flood modelling at local and basin scales. The ISBA-TOP coupled system, which is dedicated to Mediterranean flash-flood simulations, is used with two grid-cell sizes (300 and 1000 m), two soil texture datasets, and two land use databases to model 12 past flash-flood events in southeastern France. The skill of the hydrological simulations is assessed using conventional data (discharge measurements from operational networks) and proxy data such as post-event surveys and high-water marks. The results show significant differences between the experiments in terms of both the simulated river discharge and the spatial runoff, whether at the catchment scale or at the local scale. The spatial resolution has the largest impact on the hydrological simulations. In this study, it is also shown that the soil texture has a larger impact on the results than the land cover.