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

Abstract

Land use and land cover change (LULCC) is a critical factor for enhancing the soil erosion risk and land degradation process in the Wabi Shebelle Basin. Up-to-date spatial and statistical data on basin-wide erosion rates can provide an important basis for planning and conservation of soil and water ecosystems. The objectives of this study were to examine the magnitude of LULCC and consequent changes in the spatial extent of soil erosion risk, and identify priority areas for Soil and Water Conservation (SWC) in the Erer Sub-Basin, Wabi Shebelle Basin, Ethiopia. The soil loss rates were estimated using an empirical prediction model of the Revised Universal Soil Loss Equation (RUSLE) outlined in the ArcGIS environment. The estimated total annual actual soil loss at the sub-basin level was 1.01 million tons in 2000 and 1.52 million tons in 2018 with a mean erosion rate of 75.85 t ha−1 y−1 and 107.07 t ha−1 y−1, respectively. The most extensive soil loss rates were estimated in croplands and bare land cover, with a mean soil loss rate of 37.60 t ha−1 y−1 and 15.78 t ha−1 y−1, respectively. The soil erosion risk has increased by 18.28% of the total area, and decreased by 15.93%, showing that the overall soil erosion situation is worsening in the study area. We determined SWC priority areas using a Multi Criteria Decision Rule (MCDR) approach, indicating that the top three levels identified for intense SWC account for about 2.50%, 2.38%, and 2.14%, respectively. These priority levels are typically situated along the steep slopes in Babile, Fedis, Fik, Gursum, Gola Oda, Haramaya, Jarso, and Kombolcha districts that need emergency SWC measures.

Water Erosion Risk Assessment in the Kenya Great Rift Valley Region

“…The mean erosion rate for the year 1990 was estimated at 6.26 t ha −1 yr −1 with a standard deviation of 50.71 while the year 2015 presented a rate of 7.14 with a standard deviation of 40.38. In both years, the estimated mean rate of annual soil loss fell within the normal soil loss tolerances (from 5 to 11 t ha −1 yr −1 ) [14,27,46]. The amount of total annual soil loss in the KGRV region was 116 Mt yr −1 in 1990 and 132 Mt yr −1 in 2015.…”

“…Due to the direct correlation between rainfall intensity and erosion, the R factor represents the main driving factor of soil erosion [30] and contributes almost 80% of total soil loss [46]. The classical Wischmeier and Smith (1978) calculation method for R factor requires the use of storm erosivity index (EI) values of at least 20 years to account for seasonal variabilities and rainfall intensities [14,27].…”

“…The mean annual precipitation for the time periods 1981-1999 and 1999-2015 were computed from the monthly average precipitation downloaded from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) [44] database and used to calculate rainfall erosivity factors for the periods 1990 and 2015, respectively [31]. CHIRPS data is readily available at high spatial-temporal resolutions and has been shown to have significant results in determining long-term rainfall trends when compared to rain gauge station datasets for Kenya [49,50] Due to the direct correlation between rainfall intensity and erosion, the R factor represents the main driving factor of soil erosion [30] and contributes almost 80% of total soil loss [46]. The classical Wischmeier and Smith (1978) calculation method for R factor requires the use of storm erosivity index (EI) values of at least 20 years to account for seasonal variabilities and rainfall intensities [14,27].…”

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).…”

“…So far, substantial studies have been conducted recently to analyze the impacts of LU/LC on soil erosion in Ethiopia (e.g. ; (Alemu and Melesse 2020;Aneseyee et al 2020;Belihu et al 2020;Desta and Fetene 2020;Gashaw et al 2020;Woldemariam and Harka 2020;Kidaneet al 2019;Kassawmar et al 2018;Tadesse et al 2017). However, detail information on soil loss from each land use category is uncertain in several places.…”