Influence of the Geomorphology of the Okpara Watershed on Lowland Water Resources (Benin)

Abstract

Inland valleys are agro-ecosystems whose study is necessary not only for agricultural and agro-pastoral perspectives but also for the management of natural crises such as floods and droughts. This cannot be done by ignoring the catchment area which circumscribes them. The present study aims at evaluating the geomorphological parameters of the basin and their influence on the hydrological functioning of the Okpara catchment in general and the lowlands in particular for a good management of the said basin. To do so, an SRTM image was exploited thanks to GIS and Remote Sensing tools to analyze the morphometric properties of this watershed with ArcGIS 10.3 software. Through the results of this study, it can be seen that the Okpara watershed is very elongated, the relief is not very uneven with a dense hydrographic network characterized by low peak flood flows. The watershed is characterized by a permeable geological formation that favours a good infiltration of surface water and limits runoff. Thus, for a good management of the catchment area from these lowlands at the head of the hydrographic network, it is important to undertake actions to improve the storage capacity and to restore the flow channels.