Use of Land Cover Fractions Obtained from Multiple Endmember Unmixing of CHRIS/Proba Imagery for Distributed Runoff Estimation

In the last decades RS and GIS technology have been increasingly used for hydrological applications. Hydrological parameters estimation is strongly related to land cover composition. This study examines the impact of different approaches to estimate land cover distribution on the prediction and the spatial pattern of surface runoff. Land cover fractions are derived at sub-pixel scale from CHRIS/Proba data by applying Multiple Endmember Spectral Mixture Analysis (MESMA). These are used as input for a spatially distributed hydrological model (Wetspass). A fully distributed approach, where land cover fractions are specific for each cell and obtained through MESMA is compared to a semi distributed approach, where the land cover fractions for each cell are fixed a priori, based on the land-use type of the specific cell. The fully distributed approach, based on RS derived land cover estimation, proves to have a strong impact on the spatial distribution of runoff when compared to the results obtained with the more traditional, semidistributed approach. Using MESMA in combination with the Wetspass model allows making full use of the potential distributed hydrological modelling, leading to a spatially more detailed characterization of hydrological processes.