Estimation of climate and watershed management-induced potential soil loss using the USLE in Demjer watershed, Blue Nile basin, Ethiopia

Abstract

This study aimed to predict future soil loss under different climatic scenarios in the Demjer watershed, Blue Nile River Basin. The soil loss was calculated using USLE. The GCMs derived under the RCP4.5 and RCP8.5 for the period 2020–2049 were used. Three LULC scenarios were considered and the projection of the change in rainfall was estimated under the RCP4.5 and RCP8.5 scenarios. The projected mean annual precipitation increased by 6.42 and 5.95% under the RCP4.5 and RCP8.5 scenarios, respectively. The soil loss rate in the future ranged from 0 to 144.7 t ha−1y−1 and from 0 to 142.4 t ha−1y−1 for RCP4.5 and RCP8.5, respectively. Compared to the base period, the soil loss rates increased by 7.6% (RCP4.5) and 7.4% (RCP8.5). This is attributed to increase in rainfall erosivity. The LULC scenario is a major variable in reducing soil erosion rates in the future. That means, soil loss would reduce up to 33.6% of the present soil loss rate, if all the current cultivated lands with slopes >35% are covered by plantations and if open grazing land controlled. Estimation of future soil loss risk could provide evidence for preparing site-specific conservation plans, thereby enabling sustainable use of land.