Effects of climate variability and/or land use dynamics on the hydrological balance of the Cavally river catchment at Toulepleu, West Africa

The study focuses on assessing the individual and combined impacts of climate variability and land use change on hydrological responses. The results indicate that the basin, urban area, cropland, degraded forest, and open forest shows an increasing trend, while gallery forest show a decreasing trend over the period 1992-2015. Climatic variability is marked by two climatic periods (a wet one from 1980 to 1996 and a dry one from 1997 to 2016) with a 35% decrease in rainfall. Regardless of the state of the landcover used, the simulated mean annual runoff decreases by 67.92% between the wet and dry climate periods. Changes in land use between 1992 and 2015 reduce mean annual runoff by 4.71%. Analysis of the joint effect of climatic and LU variation shows a 68.96% reduction in runoff. In this catchment, the joint impact has a clearly greater effect on runoff than the climatic impact, which is greater than that of human activities. There is a need for policymakers to prioritise sustainable land use practices and integrated water resource management strategies in the area to mitigate the combined effects of climate variability and anthropogenic activities, ensuring the long-term resilience of the ecosystem and water availability for local communities. HIGHLIGHTS center dot The SWAT model was used to isolate the climate and land use change impacts on streamflow. center dot Impact of autocorrelation in the study of time series trends using modified Mann-Kendall test. center dot Hydrologic responses follow the direction of joint effects of climate and land use change. center dot Individual and combined impacts of climate and land use changes on hydrologic responses were evaluated.