The interactive effects of elevation, precipitation and lithology on karst rainfall and runoff erosivity

Abstract

Soil erosion, which is the prominent ecological and environmental problem in the karst regions of southwestern China, has seriously affected the regionecological conservation and economic development. Quantifying rainfall erosivity and runoff erosivity, can be a means to identify the dominant environmental factors involved in these mechanisms and provide a theoretical basis for mitigating soil and water loss. This aids determination of the measures required to control rocky desertification and promote the ecological restoration of karst areas. Accordingly, this study simulated the rainfall erosivity in the Sancha River Basin (SRB) between 1985 and 2014 using an adopted daily rainfall model according to the karst erosive rainfall standard. Based on the degree of rocky desertification in the karst areas, correction coefficients were applied to improve runoff erosivity calculation and estimate the runoff erosivity of the basin between 1993 and 2014. In addition, the dominant and interactive factors affecting rainfall/runoff erosivity of the diverse geomorphological types in the SRB were quantitatively identified using the geographical detector. Results showed that the rainfall erosivity between 1985 and 2014 averaged 6913.73 MJ·mm·ha−1·h−1, with an average runoff erosivity of 1121.37 m4·km−2·s−1 between 1993 and 2014. Precipitation and elevation were found to be the dominant factors shaping the spatial distributions of rainfall/runoff erosivity in the SRB. Precipitation explained over 90% of the spatial distribution in rainfall erosivity, and the q value of precipitation for runoff erosivity had no direct relationship with time. Furthermore, the interactions of elevation and precipitation, elevation and lithology type had prominent effects on rainfall erosivity and runoff erosivity in the SRB, respectively. Among them, the compound effects of elevation and precipitation could explain more than 80% of rainfall erosivity. These findings should be essential for managing soil and water loss in the karst areas.