Assessing the Impact of Urban Land Use Change on Soil Water Driven Erosion Risk: A Case Study of the Gourou Watershed, Abidjan, Côte d’Ivoire

Abstract

Vegetation cover is a crucial factor in the evolution of soil erosion, as its presence can slow it down or its absence can exacerbate it. Combating erosion risk requires knowledge of land cover types in a given region to best target erosion control measures. With this in mind, the general objective of this study is to demonstrate the impact of vegetation cover dynamics on the risk of soil erosion caused by water, using the Gourou watershed in southern Côte d'Ivoire as a case study. Landsat satellite images of the Gourou watershed were processed, and the Revised Universal Soil Equation (RUSLE) was used to spatially map soil loss within the study area. The results show a dominance of buildings and bare soils which occupy 70% of the landscape of the Gourou watershed in 2020. This spatial analysis allowed us to determine the extent of water erosion in the study area, with a distribution showing an average ranging from 556.77 t/ha/year to 633.46 t/ha/year and a percentage of highly vulnerable areas ranging from 38.95% in 2002 to 50.03% in 2020. The entire surface of the watershed would therefore be highly affected by the phenomenon of water erosion. A more advanced or more severe degradation of the vegetation cover would be detrimental to this region which already suffers from disasters such as flooding by accumulation of runoff water caused by the inability of soils to infiltrate and the silting up of drainage canals caused by soil loss and the drainage of solid waste by water towards the canals.