Ecohydrological impacts of the Bui Hydroelectric dam on riparian ecosystems in the Bui River Basin, Ghana

Large hydroelectric dams are pivotal for development yet impose profound ecohydrological trade-offs, particularly in data-scarce tropical basins. This study provides a comprehensive, basin-scale evaluation of the impacts of Ghana’s Bui Hydroelectric Dam, commissioned in 2013, by integrating multi-temporal Landsat imagery (2000–2023), vegetation (NDVI) and soil moisture (SMI) indices, and rainfall-runoff analysis. Results quantify a fundamental landscape transformation: water bodies expanded from 0.18% to 8.83%, while vegetation cover declined sharply from 80.28% (2015) to 51.50% (2023), accompanied by extensive urbanization. Basin-wide soil moisture exhibited a significant decreasing trend (Sen’s slope = −0.013 units/year). Critically, post-dam runoff responses were substantially amplified beyond rainfall expectations, indicating a weakened vegetation buffering capacity due to land cover change. The analysis demonstrates that dam impacts extend beyond reservoir inundation to drive cascading ecohydrological feedbacks, altering catchment sensitivity and threatening riparian resilience. These findings underpin the imperative for integrated catchment management in sub-Saharan Africa hydropower development, moving beyond reservoir-centric planning to sustain ecological integrity and water security.