SOIL EROSION AND ITS RELATIONSHIP WITH TOPOGRAPHICAL FACTORS IN A MOUNTAINOUS WATERSHED IN THE UPPER MEKONG RIVER IN YUNNAN PROVINCE, CHINA

摘要

Soil erosion, mainly regulated by topographical factors in complex mountainous areas, is a serious global problem. Taking the upper Mekong River in Yunnan province, China as the study area and using the USLE model in a GIS framework, we investigated the spatial distribution of soil erosion and its relationship to slope gradient, slope aspect, and elevation. The results suggest that soil erosion is a serious problem in the study area with the degree of soil loss and soil risk unevenly distributed, and the upper reach particularly vulnerable to soil erosion. Slope gradient is the primary factor regulating soil erosion, with a slope gradient between 30° to 40°, being the most serious gradient class for soil erosion. Soil erosion on the southwestern slope aspect is relatively more serious. The soil erosion modulus sharply increased with elevation; yet, soil loss generally decreased with elevation. Topographical factors, especially slope gradient and elevation, sharply regulate soil erosion in the study area.