Hydro-power dam construction and water availability in the Bui Basin of Ghana

Abstract

Bui River Basin, Bono Region, Ghana This study evaluates the hydrological impacts of the 400 megawatt hydroelectric Bui Dam built on Ghana’s Black Volta River using remote sensing, GIS, the InVEST water yield model, and IHA analysis. The InVEST model estimated a progressive increase in annual water yield, from 3.25 MCM (2000) to 4.75 MCM (2020), with a net rise of 1.50 MCM over the study period. This trend correlated with land-use changes, including forest decline (81.4–35.8 % coverage) and urban expansion (24,713.48 ha to 95,207 ha). The IHA analysis revealed severe hydrological alterations, including a 92-day extension of dry-season flows and earlier wet-season peaks by 10 days, disrupting ecological and livelihood systems. Model validation showed strong agreement between observed and simulated yields (NSE > 0.8, R² > 0.85). The findings highlight trade-offs between hydropower generation and riverine ecosystem integrity, emphasizing the need for adaptive dam management to sustain water availability. • The study shows water retention capacity was 2628.34 × 106 MCM in 2000 and reduced to 2628.31 × 106 MCM in 2020. • The construction of the dam significantly decreased water yields by 0.034MCM. • The ecological integrity of riverine ecosystems within the enclave has negatively impacted most hydrologic parameters. • Planning for hydro dams should consider the ecological, societal, and environmental impacts.