Estimation of wind and water erosion based on slope aspects in the crisscross region of the Chinese Loess Plateau

The crisscross region of the Chinese Loess Plateau is affected from both wind and water erosion, and their relative contributions remain unclear. A combination analysis of Cs-137 inventories, surface soil sample properties, and the local wind condition allows the measurements of total soil erosion, as well as the rates of wind and water erosion that are independently affected by slope aspect at a experimental site in the study area. This study selected eight straight slope for investigation. Although the slopes had similar gradients, lengths, elevations, shapes, vegetation conditions, soil types, and land-use types, they faced different aspects. This study tested the soil organic matter content, particle size, specific surface area, and Cs-137 inventory, including the mean Cs-137 reference inventory from a region of flat grassland near a century-old temple located on the top of a hillslope. Water erosion were assumed to be similar for slope aspects on condition that rainfall and environmental conditions were similar, and differences in erosion on slope aspects were mainly attributable to wind erosion. This assumption was confirmed by stepwise linear regression analysis, and wind erosion was estimated from total erosion and water erosion. The east-facing slope experienced almost no wind erosion, and erosion (91.4 t ha(-1) year(-1)) it experienced was primarily caused by water according to estimation of total erosion and analysis to wind conditions. Based on the assumption that water erosion was similar on all slopes, the west-facing slope exhibited a similar rate of water erosion to the east slope, while the rate of wind erosion was 16.9 t ha(-1) year(-1). The northwest slope had the highest wind erosion rate (42.3 t ha(-1) year(-1)), while the slope opposite to it (the southeast slope) had the highest wind deposition rate. Wind erosion on average contributed 27.4% to total erosion on windward slopes (northwest and north), while deposition occurred on the opposite leeward slopes (southeast and south). Although water erosion was found to be the primary driver of soil loss in this watershed, the effect of wind erosion cannot be neglected. It was mainly response for the erosion difference on slope aspects.