Investigating the effects of water and wind erosion on different hillslope aspects on the Loess Plateau of China by using 137Cs

Compound erosion is always more intense than singular wind or water erosion in arid and semiarid areas. However, the contribution of different exogenic agencies to compound erosion is difficult to determine. A quantitative study of the proportion of wind and water erosion in compound erosion is necessary to gain insight into and predict compound erosion. In this study, eight slopes with different aspects on a hill were selected in Jingbian County on the Chinese Loess Plateau, which is located in the crisscrossing water-wind erosion region. Compound wind-water erosion was estimated by using Cs-137 tracing technology. The contributions of wind and water erosion to compound erosion were distinguished by using two methods, including the revised universal soil loss equation (RUSLE) model and the compound erosion slope divergence characteristics (SDC) method, respectively. The results showed that the northwest windward slope had the highest total erosion rate (76.43 t ha(-1) a(-1)) on all eight slopes with different aspects. The contribution of wind and water erosion to compound erosion partitioned by using the RUSLE model was consistent with that partitioned by using the SDC. The water erosion rate was greater than the wind erosion rate on all slopes. The wind erosion rate was the greatest on the upper part of the northwest slope, which was 27.94 t ha(-1) a(-1) or 31.38 t ha(-1) a(-1), as estimated by using SDC method and the RUSLE model and accounted for 36.56 % and 41.06 % of the average annual erosion rate, respectively. The percentage of water erosion was 63.44 % and 58.94 %, respectively. The mutual validation of these two methods provided reliable relative amplitudes of wind and water erosion for compound erosion studies and provided a basis for the quantitative understanding and prediction of compound erosion.