Vegetation types and rainfall regimes impact on surface runoff and soil erosion over 10 years in karst hillslopes

Abstract

Southwest China is one of the largest contiguous karst areas in the world. Due to the particularity of geological conditions, extreme rainfall events and unreasonable land use, this region is experiencing severe soil erosion. Therefore, the main purpose of this study is to evaluate the influences of vegetation type and rainfall regime on runoff and soil loss in southwest China. The recording of 143 rainfall events from 2006 to 2015 have been divided into 5 rainfall regimes by K-means clustering method. The vegetation type included soil and water conservation forest, grassland, cropland and economic fruit forest. Results showed that vegetation type and rainfall regime both had significant influences on runoff and soil loss. Among the four vegetation types, the cropland produced the largest runoff and soil loss, and the minimum runoff and soil loss were observed in grassland. The rainfall regime I with the shortest duration and highest rainfall intensity produced the largest runoff, accounting for 45% of the total runoff. The rainfall regime IV with shorter duration and higher rainfall intensity generated the greatest soil loss, occupying about 41% of the total soil loss. The general linear model indicated that the main factors affecting runoff were vegetation type, maximum 30-minute rainfall intensity (I30) and rainfall duration, while the soil loss is highly linked to vegetation type and I30. This study suggested that grassland is a good choice to control soil erosion when land use conversion is implemented. Furthermore, replacing soil and water conservation forest with economic fruit forest can not only effectively control soil erosion, but also increase the income of residents in karst regions. Due to the low soil formation rate in karst areas, the soil erosion risk is still high and great efforts should be paid to control soil erosion and rock desertification in this region.