Shifts and drivers of riparian vegetation in the Black Volta Basin in the Savanna region of Ghana

Riparian vegetation is a functionally important ecosystem that stabilizes riverbanks, regulates hydrological processes, and supports local community livelihoods. Despite their ecological and socio-economic importance, there is a dearth of information on the long-term shifts in riparian vegetation and their underlying drivers. This study assessed two decades (2000–2020) of shifts in the boundaries of riparian vegetation in the Black Volta Basin and identified the drivers associated with these changes. Landsat surface reflectance imagery was classified using an ensemble of Maximum Likelihood and Support Vector Machine algorithms. NDVI and MNDWI were derived to quantify vegetation greenness and surface water extent, while Mann–Kendall trend tests, ANOVA, and multiple regression were used to analyze biophysical trends and drivers. Encroached land expanded between 2000 and 2010, while sparse vegetation declined from 2010 to 2020. NDVI increased significantly from 0.138 to 0.166, despite declines in precipitation. NDVI was positively associated with precipitation and temperature but negatively associated with MNDWI, indicating that hydrological expansion reduces greenness while climatic warming enhances vegetation productivity in drought-tolerant or human-modified landscapes. These findings reveal greening that coexists with degradation of natural riparian vegetation, highlighting the need for integrated landscape management, enforcement of riparian buffers, and restoration of gallery forests.