Comparing potential risk of soil erosion using RUSLE and MCDA techniques in Central Ethiopia

Abstract

Water erosion remains a threat to subsistence agriculture. Insofar, spatial-based soil erosion risk mapping is investigated to assist interventions across varying scales. The Revised Universal Soil Loss Equation (RUSLE) model and Multi-Criteria Decision Analysis (MCDA) techniques are most recently used to map soil erosion hotspots in Ethiopia. Aligned to that, this study aims to identify and compare the risk of soil erosion using the RUSLE and MCDA approach in Sodo watershed covering 80.54 km2, central Ethiopia. The adjusted parameters of RUSLE and MCDA demanding soil, land use, and terrain feature data were used for the study. Finally, cross-comparison was effected to check their consistency. The RUSLE model shows 68.91% of the study area accounted for a soil loss of 75 ton/ha/year. Generally, the mean annual gross soil loss amounts to 783,170 tons, with the mean soil loss rate of 35.28 tons/ha/year. This is 1.96 times higher than the tolerable limit for Ethiopian highlands. The MCDA result shows that 5.6%, 50.57%, and 43.83% of the watershed are highly, moderately, and slightly sensitive to soil erosion, respectively. The overlay result reveals that 49.4% of the risk and location of land susceptibility was similarly estimated by RUSLE and MCDA. This is a “good agreement” with a Kappa value of 0.62. The consistency increases with a decreasing level of sensitivity. Therefore, this could be an input for local decision-makers and experts at large.