Spatiotemporal dynamic of soil erosion and the key factors impact processes over semi-arid catchments in Southwest China

The heterogeneity of geographic environments and vegetation types plays a crucial role in determining soil erosion patterns. Highlighting the influence of environmental factors and their gradient changes on soil erosion is key to effective control and management. In this study, conducted in the arid-hot valley area of the Jinsha River, one of the main sand-producing areas in the Yangtze River Basin, we considered the topographic factors and land cover and applied the Revised Universal Soil Loss Equation (RULSE) with geographic information system (GIS) was applied to quantify the contribution and change pattern of different factors to soil erosion in the arid-hot valleys. Then, the spatial and temporal patterns of soil erosion in 2000 and 2015 were analyzed, showing erosion amount of 1812.96 t/(km(2)a) and 1965.98 t/(km(2)a), respectively. The increase in erosion was attributed to the frequency of heavy rainfall events. In terms of spatial distribution, strong soil erosion has been mainly observed in arid-hot basins, such as Yuanmou and Huaping. The soil erosion modulus (SEM) was closely connected to topographical elements, increasing incrementally with slope. High soil erosion areas were predominantly distributed across slopes between 18 degrees and 36 degrees. In contrast, SEM decreased gradually with increasing altitude, with strong erosion occurring primarily below 2000 m. SEM for different land use types followed this order: bare land > cultivated land > grassland > forest > paddy land. Based on the relationship between vegetation cover and soil erosion, the area could be roughly divided into three types of area by vegetation coverage: erosion control areas (30% vegetation coverage), erosion-vegetation transition areas (30-70%), and vegetation control areas (>70%). These results provide an essential reference for assessing soil erosion patterns and implementation of ecological vegetation restoration measures in arid-hot valleys.