ANALYSE HYDROMORPHOMÉTRIQUE ET ÉVALUATION DES RISQUES HYDROLOGIQUES DANS LE BASSIN VERSANT DE LA LUKEMI (KIKWIT, RDC).

Abstract

This study analyzes the hydromorphometric parameters of the Lukemi River watershed (Kikwit, Democratic Republic of the Congo) in order to assess their role in triggering and amplifying hydrological hazards. In a context of rapid urbanization, degradation of vegetation cover, and rainfall variability, knowledge of the watershed's physical characteristics is essential to preventing flooding and erosion. The approach is based on an ALOS PALSAR Digital Elevation Model (DEM) with a 12.5 m resolution, processed in ArcGIS Pro to extract morphometric and hydrographic parameters. With an area of 42.2 km² and a perimeter of 33.9 km, the watershed shows a Gravelius compactness index of 1.47 (elongated shape), moderate relief, and a low drainage density (0.66 km/km²), giving a concentration time of approximately 4 h 52 min. The SPI (0 to 556) and TWI (0.53 to 17.26) maps reveal a heterogeneous distribution of erosive energy and water accumulation zones. The 2025 land-cover classification and the Normalized Difference Built-up Index (NDBI) derived from a 2025 Sentinel-2 image show continuous urban coverage over the lower third of the watershed, where positive NDBI values (up to 0.27) confirm effective surface sealing, while vegetation survives only in narrow riparian corridors. Anthropogenic pressures alter the watershed's hydrological functioning and increase its vulnerability to flooding and erosion. The study concludes on the need to integrate these parameters into urban planning and stormwater management.