Investigating the spatial distribution of soil erosion and deposition in a small catchment on the Loess Plateau of China, using 137Cs

An understanding of the spatial distribution of soil erosion and deposition in a catchment is important for designing soil and water conservation measures. Traditional monitoring techniques provide limited information on the spatial patterns of erosion and deposition. The fallout radionuclide 137Cs was used to document rates and patterns of soil redistribution within a small (0.17 km2) gully catchment located near An'sai in Shaanxi Province, representative of the Loess Plateau of China. The local reference inventory was estimated to be 2266 Bq m−2 and the 137Cs inventories of 198 soil cores collected from the catchment, ranged from 0 to 3849 Bq m−2. The coefficient of variation of the inventories of the individual cores was 0.85, reflecting the complex pattern of 137Cs redistribution by soil erosion and deposition. Estimates of erosion rates derived from 137Cs measurement ranged from less than 25 to 150 Mg ha−1 year−1, with about 70% of the net soil loss from the catchment coming from the gully area. The 137Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small catchment.