BayCEER Workshop 2025

Climate and land use change impacts on flood in the Mono River Basin (Benin and Togo)

Flooding is prominent in West Africa, and is expected to be exacerbated, due to global climate and land-use changes. This study assessed the impacts of future climate and land-use changes on streamflow in the Mono river catchment area of Benin and Togo. Climate scenarios from the representative concentration pathways, RCP 4.5 and RCP 8.5, and land-use projection at the horizon of 2070 were used for runoff simulation. The study also examined the potential impact of the upcoming Adjarala hydroelectric dam in the basin. The Soil and Water Assessment Tool (SWAT) was used for  runoff simulation. SWAT showed good performance during the calibration (KGE = 0.83) and validation (KGE = 0.68) steps. Results show an increase in the magnitude of extreme runoff in the future. Events of 10-year return periods during 1987–2010 are expected to become 2-year return-period events under the climate- and land-use-change scenarios considered. The planned Adjarala dam showed potentials for reducing extreme peaks. However, the new dam may also affect water availability during low flow periods. Adaptation measures as well as sustainable land-use and dam-management options should be identified, to alleviate the impacts of the projected changes.