Gully Erosion associated with Peri-Urbanization: Focus on the Catchments around Kimwenza in the South of Kinshasa (DR. Congo)

The catchments draining Kimwenza, a small plateau in Southern Kinshasa town (DR Congo), are undergoing rapid and extensive peri-urbanization with limited planning. This research focuses on gully erosion processes associated with different infrastructures. The objectives are to characterize the morphometry of the catchments, describe the surface water flow network, assess the runoff rates, and propose an appropriate drainage solution to collect runoff. It appears that these basins have a high drainage density, ranging from approximately 1,800 to over 11,000 m/km², with a general average of around 6,570 m/km², as determined through field and laboratory investigations. In addition, all the basins in this area are somewhat rounded in shape and modest, which means they are more likely to have rapid rainwater concentration and response times. As a result, runoff flow can be torrential, especially since 80 % of this sector has slopes greater than 8%. The peak rate of surface runoff can exceed 650 l/s/ha, according to an analysis of active showers and their intensities. Due to the incoherent soil structure, mainly composed of sand, 30 gullies were mapped with an average length of 560 meters, a width of 27 meters, and a depth of 10 meters. Under these conditions, mitigating the gully phenomenon requires significantly reducing runoff flows