Water resources availability in the Mefou basin, Cameroon: under current and future climate, and land use and land cover

To anticipate disasters (drought, floods, etc.) caused by environmental forcings and reduce their impacts on its fragile economy, sub-Saharan Africa needs a good knowledge of the availability of current water resources and reliable hydroclimatic forecasts. The objective of this study is to evaluate the availability of current water resources and their future evolution in a forest watershed undergoing accelerated urbanization (Mefou), but also to separate the respective impact of land use and land cover change (LULCC) and climate variability (CV) on the evolution of this resource. For this, the SWAT (Soil and Water Assessment Tool) model was used. The performance of this model is satisfactory in calibration and validation, with R2 and NSE greater than 0.64. Biases lower than - 7.9% also attest to this good performance. The RCA4 model is, however, the one for which the forecasts seem the most reliable. A statistical study carried out over the historical period (2001-2005) demonstrated that the flows simulated using data from this model are closer to the observed flows. This statistical relationship is materialized by R2 and NSE greater than 0.56. Concerning land use and land cover (LULC) patterns, their future change are expected to be significant and essentially characterized by an increase in impervious areas and a reduction in forest and water bodies. These changes will cause an increase in flows, including in the event of a moderate decrease in precipitation, as predicted by the RCA4 and REMO models. The impact of LULCC will be preponderant in the variability of future flows if precipitation evolves according to the forecasts of the most reliable model (RCA4). The impact scores of this forcing on the water balance components (WBCs) sufficiently prove this. They are higher than those of the impact of CV for all WBCs, except evapotranspiration (ETP). The results of this study could contribute to improving water resource management in the basin studied and the region.