Abel, Afouda, Applied Hydrology Laboratory (LHA), University of Abomey-Calavi (UAC), Cotonou, BP, 4521, Benin; West African Science Service Center on Climate Change and Adapted Land Use (WASCAL), GRP Climate Change and Water Resources, University of Abomey-Calavi (UAC), Abomey-Calavi, BP, 2008, Benin