Evaluating Water Resource Availability in Lake Guiers (Senegal) by 2050 Under Climate Change and Human Activities Using the WEAP Model

This study assesses the future availability of water resources in Lake Guiers by 2050, considering the combined impacts of climate change and human activities, using the Water Evaluation and Planning System. As Senegal’s main freshwater source, the lake faces growing pressure from agricultural expansion, aquatic plant overgrowth, competing stakeholder demands, and increasing water use. The study combines field data on hydrological flows and agricultural water use with climate projections under the Shared Socioeconomic Pathways 4.5 and 8.5 scenarios. Climate data were downscaled and bias-corrected using CMhyd, multiple linear regression, and the Mann–Kendall test. Model calibration showed strong performance (NSE = 0.95; R2 = 0.96). Results reveal decreasing precipitation and rising temperatures under both scenarios. Agricultural withdrawals (79,331,457.14 m3/year) already exceed crop water needs (69,115,088.03 m3/year), resulting in significant water losses estimated at over 10 million m3 per year. Scenario analysis indicates that high water demand under Shared Socioeconomic Pathways SSP8.5 could lead to critical declines in lake volume as early as 2026 (550 million m3), while moderate demand growth under SSP4.5 could maintain water availability until 2050. The proposed PREFERLO-Grand Transfer project would add further stress to the lake’s capacity. These findings emphasize the urgent need for sustainable water management and policy actions.