The present study conducted in the Oyun River watershed (Ijagbo, Kwara State, Nigeria) was aimed at estimating and mapping its potential annual soil loss using primary and secondary data. Soil loss was estimated using the Universal Soil Loss Equation (USLE) with its parameters analyzed and integrated into the raster calculator in the geoprocessing tools of the ArcGIS 10.5 environment. The results showed an increase in erosivity from 70.07 MJ mm ha–1 per year in the period 1997–2001 to 83.48 MJ cm ha–1 per year within 2012–2017 representing a ca. 19 % increase. Rainfall erosivity has been projected to reach 94.17 MJ cm ha–1 per year in the next decade. Strong slopes of 15–30% and 30–45% gradient covering 19.77 % (13.05 ha) and 0.82 % (0.54 ha) of the watershed, respectively, and soil management practices applied there have been found the major soil loss determinants. Soil loss ranged from 0 to 35 t ha–1per year with the mean annual value of 3.39 t ha–1. Total annual soil loss in the watershed was calculated to be 254.25 t. Contouring, the dominant erosion control practice in the watershed, was substantially ineffective; however, its substitution with stripping and terracing indicated a 50% and 80% reduction potential in soil loss, respectively. About 11.62% of the watershed (erosion hotspots) recorded soil loss above the maximum tolerable limit of 12 t ha–1 per year set by FAO.
arable land, soil loss, USLE, ArcGIS, erosion hotspot, Kwara State
Ahamefule,.H.E., Olaniyan, J.O., Yusuf, A.,Amana,. M.S.,Eifediyi, E.K.,Ukelina, C.U.,Taiwo, R.A., Nwokocha, C.C., Fatola, F.A.:(2021): Estimation of Potential Soil Erosion Risk in a Typical Guinea Savannah Agricultural Watershed of Nigeria. Scientia Agriculturae Bohemica, 52, 83-94. DOI: 10.2478/sab-2021-0010