Study on the effects of rainfall and slope on soil erosion in karst rocky mountain areas of northern Guangxi Zhuang Autonomous Region

Abstract

[Objective] This study aims to identify the variation patterns of soil erosion under different conditions and provide scientific guidance for the prevention and control of soil erosion. [Methods] The study focused on soil erosion on the slope surfaces in the karst rocky mountain areas of northern Guangxi. Based on indoor artificial rainfall simulation experiments, the effects of different fracture degrees, rainfall intensities, and slopes on runoff and sediment yield were systematically analyzed. The accuracy and validity of the simulation experiment were verified by comparing it with field monitoring data on soil erosion. [Results] The results revealed the following:(1) When the fracture degree remained constant, at a rainfall intensity of 15 mm/h, compared to the soil erosion at a 0° slope, the average increase in soil erosion at 3°, 6°, and 9° slope was 70.13%. At a rainfall intensity of 30 mm/h, compared to the soil erosion at a 0° slope, the average increase in soil erosion at 3°, 6°, and 9° slopes was 42.53%. At a rainfall intensity of 60 mm/h, compared to the soil erosion at a 0° slope, the average increase in soil erosion at 3°, 6°, and 9° slope was 35.07%. As the slope increased, soil erosion increased. However, the rate of increase gradually slowed, with the deceleration becoming more apparent.(2) When the slope and rainfall intensity were constant, the fracture degree had a relatively small effect on soil erosion. As the fracture degree increased, soil erosion generally showed a decreasing trend, but the reduction was modest. When the slope and fracture degree were constant, and rainfall intensity was 15~30 mm/h, higher rainfall intensity resulted in a greater increase in soil erosion. When the rainfall intensity exceeded 30 mm/h, soil erosion continued to increase, but the rate of increase slowed.(3) The Pearson correlation coefficient calculation revealed that rainfall intensity had a greater impact on soil erosion than slope. At 3° and 6° slopes, the field monitoring results were consistent with the laboratory test results, indicating that the indoor artificial rainfall simulation was suitable for studying runoff characteristics in karst areas. [Conclusion] The study provides theoretical guidance and technical support for soil erosion prevention and ecological restoration in the karst rocky mountain areas of northern Guangxi.

Keywords

rainfall / rainfall intensity / runoff / soil erosion / slope / northern Guangxi