Soil loss estimation of Karnali river basin, Nepal

Soil loss estimation is the prerequisite for deciding priorities for watershed management which in turn is important to maintain human needs and ecosystem services. Karnali River Basin in Nepal is highly susceptible to soil erosion but limited studies have elucidated its basin-specific erosion status utilizing advanced computations. This study was designed with the objectives of delineating the river basin and estimating its soil loss using the Revised Universal Soil Loss Equation (RUSLE) and Geographical Information System (GIS). The study individually calculated the required factors through Google Earth Engine and raster analysis in Arc GIS to create the potential soil loss map. The map depicted that the largest proportion (27%) of the area of the river basin was expected within the erosion category of 3 to 10 t ha(-1) year(-1), followed by 10 to 25 t ha(-1) year(-1) (22%) and less than 1 t ha(-1) year(-1) (22%). Only 2% of the land within the basin was at risk of erosion of more than 50 t ha(-1) year(-1). The Average soil loss from Karnali was estimated at 9.85 t ha(-1) year(-1). The total soil being lost per year from the Karnali River is 48,279,696 tonnes. The highest amount of soil loss was estimated in Dolpa followed by Mugu, Humla, Rukum East, and then Rukum West districts of the Karnali river basin. The results can be of pivotal inference in further planning, and prioritizing management and protection areas for the local and provincial governments.