SWAT-based analysis of hydrological functioning and climate trends in the Upper Senegal River

The upper Senegal River basin is vital for agriculture, hydropower, and ecosystem services in Mali, Senegal, and Guinea. However, its hydrological behavior remains poorly understood due to climatic variability and limited in situ data. This study evaluates the basin's hydrological dynamics using the Soil and Water Assessment Tool (SWAT). Six key monitoring stations (Bakel, Kayes, Gourbassy, Oualia, Bafing Makana, and Daka Saidou) were analyzed using hydroclimatic data from 1983 to 2021. Calibration results showed satisfactory performance, with Nash-Sutcliffe Efficiency (NSE) values reaching 0.74 at upstream stations, while performance decreased downstream. Validation performance slightly declined compared to calibration. Trend analysis revealed significant annual increases in precipitation, soil moisture, and streamflow, while evapotranspiration showed no clear trend. Seasonal patterns were characterized by high rainfall and runoff between July and September. These findings indicate increasing hydrological variability likely driven by climate change and highlight the need for integrated water management to ensure sustainable resource use and mitigate increasing flood risks. The study provides critical insights for policymakers to strengthen water security and climate resilience in the Senegal River Basin.