Abstract. The aim of this article is to test the sensitivity of the Land Surface Model (LSM) ORCHIDEE to infiltration processes in the West African region, and to validate the resulting version of ORCHIDEE against African river discharges. The parameterizations to take into account the effects of flat areas, ponds and floodplains on surface infiltration, and the effect of roots and deep-soil compactness on infiltration are first described. It is shown that the surface infiltration processes have a stronger impact in the soudano-sahelian region and more generally in semi-arid African basins, whereas the rootzone and deep-soil infiltration also play a role in the guinean region and in the intermediate basins between arid and humid ones. In the equatorial region and the semi-humid basins, infiltration processes generally play a minor role. The infiltration parameterizations may explain part of the difference between simulated and observed river discharge in semi-arid and intermediate basins. So ORCHIDEE could be recalibrated to reduce the discharge errors. However, different sources of uncertainty might also explain part of the error. Indeed, the precipitation forcing in the whole West African region, the long-term storage in the soudano-sahelian region, the soil types in the guinean region and the vegetation types in the equatorial region are significant sources of errors. Therefore, a denser monitoring of the hydrological cycle at different scales in West Africa would ensure the reliability of future calibrations for the infiltration parameterizations.
Multi-Objective Model-Based Assessment of Green-Grey Infrastructures for Urban Flood Mitigation
