Estimation of water-induced soil erosion levels across the rangelands of Ethiopia: an integrated RUSLE and GIS analysis

Abstract

Soil erosion poses a significant global threat, leading to widespread land degradation and the depletion of nutrient-rich topsoil. Understanding the spatial distribution of soil erosion is crucial for implementing effective management practices and preventing further erosion. This study utilized an analytical tool integrating the Revised Universal Soil Erosion Equation (RUSLE) with geographic information systems (GIS) to estimate water-induced soil erosion across the rangelands and other land use categories in Ethiopia. Rangelands, constituting 68% of Ethiopia’s total land area, are essential for the livelihoods of millions of pastoralists and agropastoralists. Input data for the analysis were gathered from multiple sources, including in situ observations and remotely sensed data with various spatial resolutions. The estimated soil erosion rates were validated using previously published data from literature. Our results revealed significant variation in soil erosion, ranging from zero to 250 t ha⁻¹ yr-1. The average soil loss across the country was estimated at 13.5 t ha⁻¹ yr⁻¹, amounting to an annual soil loss of about 1.5 billion tons, making Ethiopia one of the most severely affected countries by soil erosion worldwide. Disaggregated annual soil erosion estimates indicated that the highest soil loss occurs in rangelands (18 t ha⁻¹), sparsely vegetated (bare land) areas (16 t ha⁻¹), cultivated areas (10 t ha⁻¹), and forest areas (8 t ha⁻¹). These results underscore the urgent need to implement appropriate soil and water conservation practices across rangelands, embracing Sustainable Land Management practices that can significantly reduce soil erosion. Such efforts will support sustainable land resource use and potentially unlock new opportunities for the country.