Landslide susceptibility assessment by mapping and diachronic analysis: Case of Bushwira (Democratic Republic of Congo)

Abstract

This work contributes to the study of the susceptibility of land in the Great Lakes region to mass movements. The aim is to understand the study of physical and anthropogenic natural phenomena leading to the triggering of landslides in the Bushwira area in Kabare territory (South Kivu, Democratic Republic of Congo – DRC). For this purpose, mapping and diachronic analysis of land use were carried out. This investigation first focused the inventory and the determination of the ongoing processes and the morphometric parameters of the landslides. Twelve (12) landslides were inventoried including 6 rotational, 4 translational and 2 “nonidentified mechanism of failure” landslides. The diachronic analysis carried out based on the observations of Google Earth and LANDSAT satellite images, has revealed a significant change in land use in the study area. The amplification of landslides in the study area is due to the presence of clay soil; steep slopes; slopes facing northwest, south and north; inappropriate deforestation and exploitation of construction materials. The lithology, topography, pedology and hydrology are the natural physical factors that predispose the Bushwira sector to landslide hazards. Eight orientation classes have been identified, 35% of which are northwest facing (292.5°–337.5°). Slopes facing northwest followed by those facing south and north are more sensitive to movement in this area. North-east and east-facing slopes are not affected by landslides. This indicates that the slopes oriented towards the North-West followed by those oriented towards the South and the North are more susceptible to sliding in this area. It is recommended to build adequate retaining structures offered by geotechnical studies before any human achievement of notorious importance.