Soil erosion mapping and severity analysis based on RUSLE model and local perception in the Beshillo Catchment of the Blue Nile Basin, Ethiopia

Abstract

Background: Water induced soil erosion is the most prevailing form of land resources deterioration in the highlands of Ethiopia, where huge amount of fertile soil is being lost annually. The purpose of this study was to estimate and map mean annual soil loss rates in the Gedalas watershed of the Blue Nile Basin, Northeastern Ethiopia. The estimation was carried out by using RUSLE model coupled with local perceptions. Soil, land use/cover, DEM, rainfall and support practice data were used as an input parameters. The raster layers were processed to present the required input parameters in ArcGIS platform and finally the inputs were multiplied together to quantify annual average soil loss rate and generate intensity maps of the watershed. Results: The estimated annual mean soil loss rate of the watershed was found to be 37 t ha −1 year −1 , which is more than two times higher as compared to the maximum tolerable soil loss value (16 t ha −1 year −1) and the annual erosion rates range from 0 to above 935 ton ha −1 year −1. The annual mean soil loss values below 5 ton ha −1 year −1 were rated as very slight, while those above 50 ton ha −1 year −1 were categorized as very severe soil erosion risk. Areas experiencing values between these two were further classified into slight, moderate, and severe erosion zones. Soil loss in more than 1/3rd of the study area (36.4%) was below moderate (< 15 t ha −1 year −1). Nearly one-fourth (25.5%) of the watershed area experienced moderate (between 15 and 30 ton t ha −1 year −1) soil loss values. Only 14% of the watershed areas were classified under severe to extremely severe (> 30 t ha −1 year −1) soil erosion risk zones. While 62% of the watershed still undergoes from very slight to moderate levels of soil loss, yet 72.6% of soil erosion occurred in zones less than 3200 m in elevation which represents more than half (51%) of the total surface area of the watershed. The study also demonstrated that the northeastern parts of the watershed suffer more from high soil erosion risk due to steep slope and rugged landforms of the area. Similarly, 43% and 35% of soil erosion occurred on cropland and grasslands areas, respectively. Conclusion: The quantitative soil loss estimation results and farmers' perception of soil erosion revealed that soil erosion has still remained significant problems in the watershed. The results underscore the urgent need for comprehensive and site-specific SLM practices in the watershed.

Effect of Land Use and Land Cover Change on Soil Erosion in Erer Sub-Basin, Northeast Wabi Shebelle Basin, Ethiopia

“…Our findings coincide with those of the recent study by Yesuph and Dagnew [128] who showed that the cropland under a mono-cropping and intensive cultivation in the upslope areas were responsible for severe soil erosion in the Beshillo Catchment of the Blue Nile Basin. Validating the present study's findings, Belayneh et al [120] also pointed out that cultivated land with a mean erosion rate of 45.68 t ha −1 yr −1 accounted for 62.06% of the total soil loss from the Gumara Watershed of the northwestern Ethiopia highland.…”

“…The estimated mean rate of soil loss is also higher than the findings of previous investigators in the Upper Wabi Shebelle Basin [18,67,68,71], and other river basins in Ethiopia [126,127]. On the contrary, the estimated soil erosion rates are much lower than the local scale studies that estimated the soil loss rate of 935 t ha −1 y −1 in the Beshillo Catchment of the Blue Nile Basin [128]; 243 t ha −1 y −1 in northwestern highlands Ethiopia [129], and 321 t ha −1 y −1 in the eastern escarpment of Wollo [130]. Table 8 presents the estimated soil loss from each LULC class in 2000 and 2018.…”

Effect of Land Use and Land Cover Change on Soil Erosion in Erer Sub-Basin, Northeast Wabi Shebelle Basin, Ethiopia

“…Mean soil loss rate with respect LULC classes in the Erer Sub-Basin.Our findings coincide with those of the recent study by Yesuph and Dagnew[130] who showed that the cropland under a mono-cropping and intensive cultivation in the upslope areas were responsible for severe soil erosion in the Beshillo Catchment of the Blue Nile Basin. Validating the present study's findings, Belayneh et al[122] also pointed out that cultivated land with a mean erosion rate of 45.68 t ha −1 yr −1 accounted for 62.06% of the total soil loss from the Gumara Watershed of the northwestern Ethiopia highland.…”

“…The estimated mean rate of soil loss is also higher than the findings of previous investigators in the Upper Wabi Shebelle Basin [18,67,68,71], and other river basins in Ethiopia [128,129]. On the contrary, the estimated soil erosion rates are much lower than the local scale studies that estimated the soil loss rate of 935 t ha −1 y −1 in the Beshillo Catchment of the Blue Nile Basin [130]; 243 t ha −1 y −1 in northwestern highlands Ethiopia [131], and 321 t ha −1 y −1 in the eastern escarpment of Wollo [132].…”

Impact of Land Use and Land Cover Change on Soil Erosion Using Rusle Model And Gis: A Case of Temeji Watershed, Western Ethiopia

“…The RUSLE model is highly recommended to soil loss estimation due to its compatibility suitability with GIS technology (Jasrotia and Singh 2006;Prasannakumar et al 2012) and applicability in limited data conditions (Belayneh et al 2019). This model was widely used to estimate the mean annual soil loss at worldwide (Woldemariam and Harka 2020;Kidane et al 2019;Yesuph and Dagnaw 2019;Renard et al 1997). The total annual soil loss was estimated by raster grid spatial analysis of the six parameters (Renard et al 1997;Hurni 1985;Wischmeier and Smith 1978).…”