Assessing current and projected soil loss under changing land use and climate using RUSLE with Remote sensing and GIS in the Lake Tana Basin, Upper Blue Nile River Basin, Ethiopia

Abstract

Erosion of soil in the Lake Tana basin poses a critical economic and environmental crisis due to its impacts on agriculture productivity, food security and reservoir sedimentations. This study assesses soil erosion hazards by considering changes of land use and the climate. Simulation of land use change was conducted using CA_Markov chain model while climate was downscaledusing statistical techniques from CanESM2 model. The integration of the revised universal soil loss equation (RUSLE) with a geographic information system and remote sensing were used to estimate the soil loss. To quantify soil loss, six RUSLE model parameters were used: rainfall erosivity (R), soil erodibility (K), topography (LS), cover management (C), support and conservation practices (P). The average annual loss of soil by the 2080s in the basin is projected to be 7.7, 7.5 and 8.3 tons per hectare per year for changes land use, combined changes in land use and climate, and changes in climate under RCP8.5, respectively. Furthermore, by the end of this century, the soil loss in the basin tends to increase by 10.8%, 3.4% and 2.2% by considering changes in land use pattern, combined changes in land use and climate, and changes in climate, respectively, suggesting the aggravation of soil erosion in the basin. Accordingly, the effects of climate variability on annual average loss of soil are relatively higher than the combined effects of changing climate and land use. Consequently, the integration of RUSLE model with geospatial technology is recommended for an effective soil and water conservation measures.