Estimation of soil erosion using RUSLE modeling and geospatial tools in a tea production watershed (Chisheke in Walungu), eastern Democratic Republic of Congo

Abstract

Soil erosion is a major concern for the agricultural production as it leads to topsoil losses and decreased soil fertility, especially in highland regions. Walungu’s Chisheke watershed supports the staple food and industrial tea production, which are the basis for the food and income security in the region. The Chisheke watershed’s soil loss estimate is, therefore, vital for its sustainable management to maximize benefit to farmers and the region economy which is heavily dependent on tea products and sub-products’ export. To facilitate the implementation of an erosion management plan, this study estimated soil losses in the Chisheke watershed using the Revised Soil Loss Equation (RUSLE). Besides, it assessed the land-use and land cover change impacts on the soil erosion as well as the farmer's perception on the currently experienced watershed soil erosion. Results showed that soil losses varied from 0 to 400 t ha−1 yr−1, with an average of 24 t ha−1 yr−1. The soil loss rates depended on the land-use and land cover changes. The highest soil losses were those from settlements (60 t ha−1 yr−1) and bare soils (45 t ha−1 yr−1) while agriculture and tea plantation (8.5 t ha−1 yr−1) and forest (6.5 t ha−1 yr−1) recorded lower soil losses. However, extreme soil erosive risks were observed in steep slope agricultural lands. Farmers acknowledged the soil erosion as a major concern in their area and used the soil and water conservation practices to mitigate its negative effects. The predominant soil and water conservation practices included the manure (72%), compost (57%) and green manure (45%) applications as well as the promotion of mashes and wetlands for vegetable crop production. The soil erosion maps provided in this study are valuable resources to effectively implement sustainable soil erosion management strategies in the Chisheke watershed and other areas with similar agro-ecological conditions.