Spatio-temporal Dynamics of Vegetation Cover and Flood Vulnerability in Uvira City of DRC (1990-2024)

Abstract

Secondary African cities are increasingly trapped between rapid, unplanned urbanization and escalating climate-related hazards. Uvira (DRC), strategically located between the steep Mitumba Mountains and Lake Tanganyika, exemplifies this critical vulnerability. Methods: This study investigate the 34-year (1990-2024) spatio-temporal interactions between vegetation dynamics and flood hazards using an integrated remote sensing and GIS approach. Multi-temporal Landsat and Sentinel-2 imagery were processed to derive NDVI and NDWI indices, coupled with Random Forest LULC classification (Kappa > 0.85) and Digital Elevation Model (DEM) analysis. Results: findings quantify a profound ecological collapse, characterized by a 39.6% net reduction in vegetation cover and a sixfold increase in bare soils since 2010. This loss of green infrastructure have fundamentally altered the catchment;s hydrological response, as evidenced by a 7.8% expansion of water surface area (NDWI) in low-lying coastal zones. The topographic "funnel effect" of Uvira;s steep slopes, combined with the erosion of natural hydraulic resistance, have also transformed seasonal discharge into destructive flash floods. The study demonstrated that the "coastal squeeze";the convergence of rising lake levels and urban encroachment; has institutionalized flood risk as a structural component of the landscape. We argue for the urgent integration of Nature-based Solutions (NbS), specifically upstream reforestation and strict enforcement of non-aedificandi zones, to restore essential hydraulic regulation services and safeguard vulnerable populations.