Integrating Geographical Information Systems and Remote Sensing for Identifying the Driving Factors of Dynamic Changes in Soil Erosion Over Semi-Arid Catchments in Southwest China

Soil erosion, which is motivated by multiple external factors, decreases soil fertility and threatens the world’s agriculture production and terrestrial ecosystems. In southwest of China, arid-hot valleys of the Jinsha River are highly susceptible to soil erosion owing to the fragile ecosystem development and frequent geologic hazards. This study fully considered the topographic factors and land cover and introduced the improved calculation method for soil erosion elements to establish the Revised Universal Soil Loss Equation (RULSE) model with geographic information system (GIS), to quantify the contribution and change pattern of different factors to soil erosion in the arid-hot valleys at spatial-temporal scale. The results showed that the amount of erosion in 2015 (1965.98 t/(km2·a)) was greater than that in 2000 (1812.96 t/(km2·a)), attributable to the frequency of heavy rainfall events. In terms of spatial distribution, strong soil erosion was mainly observed in arid and hot basins, such as Yuanmou and Huaping. The soil erosion modulus (SEM) was closely connected to topographical elements. SEM increased gradually with increasing slope and the intense soil erosion regions mainly distributed in slopes between 18° and 36°. In contrast, SEM gradually decreased with increasing altitude, and erosion mainly occurred at altitudes below 2000 m. The SEM of different land use types followed the order: bare land > dry land > grassland > forest > paddy field. Then, according to the relationship between vegetation coverage and soil erosion, the area could be roughly divided into erosion control areas with low vegetation coverage (<30%), erosion-vegetation transition areas with moderate vegetation coverage (30-70%), and vegetation control areas with high vegetation coverage (>70%). These findings could provide an important reference for assessing characteristics of soil erosion in arid-hot valleys and implementing vegetation ecological restoration measures