Characteristics of soil erosion in different land-use patterns under natural rainfall

Land degradation due to soil erosion is a major problem in mountainous areas. It is crucially important to understand the law of soil erosion under different land-use patterns with rainfall variability. We studied Qingshuihe Watershed in the Chongli district of the Zhangjiakou area. Four runoff plots, including caragana, corn, apricot trees, and barren grassland, were designed on the typical slopes of Xigou and Donggou locations. The 270 natural rainfall events observed from 2014 to 2016 were used to form a rainfall gradient. The relationship between runoff and sediment yield was analyzed. Results showed that the monthly rainfall of the slope runoff plot in the Chongli mountain area presented the trend of concentrated rainfall in summer, mainly from June to September, accounting for 82.4% of the total rainfall in 2014–2016, which was far higher than that in other months. Starting from April to May every year, the rainfall increased with time, then from July to September, the rainfall decreased gradually, but it was still at the high level of the whole year. Among the four ecosystems, the caragana-field has the best effect on reducing the kinetic energy of rainfall and runoff, which can effectively reduce the runoff and sediment yield of the slope and reduce the intensity of soil erosion. In terms of the total amount of runoff and sediment, the runoff and sediment yield of the caragana-field reduced by 74%–87% and 64%–86% compared with that of the grassland. Comparing different land-use types, the caragana plantation would be conducive to conserving soil and water resources.