降雨和坡度对桂北岩溶石山地区水土流失的影响研究

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

摘要

【目的】为识别不同条件影响下土壤流失量的变化规律以及科学防治水土流失，【方法】以桂北岩溶石山地区坡面水土流失为研究对象，基于室内人工降雨模拟试验，系统分析了不同裂隙度、不同降雨强度以及不同坡度对岩溶石山地区坡面径流、产沙的影响；并结合水土流失野外监测数据，验证了模拟试验的准确性和有效性。【结果】结果表明：(1)裂隙度恒定，降雨强度为15 mm/h时，与坡度为0°的土壤流失量相比，坡度为3°、6°、9°的土壤流失量平均增长率为70.13%;降雨强度为30 mm/h时，相较于坡度为0°的土壤流失量，坡度为3°、6°、9°的土壤流失量平均增长率为42.53%;降雨强度为60 mm/h时，与坡度为0°的土壤流失量相比，坡度3°、6°、9°的土壤流失量平均增长率为35.07%。坡度越大地表土壤流失量越多，但土壤流失量增长速率逐渐放缓，且放缓趋势较为明显。(2)坡度、降雨强度恒定时，裂隙度对土壤流失量的影响较小，随着裂隙度的增大，土壤流失量总体呈下降趋势，并且减少幅度比较小。坡度、裂隙度恒定时，降雨强度在15~30 mm/h时，降雨强度越大地表土壤流失量增长率越大；当降雨强度大于30 mm/h,土壤流失量仍然在增大，但增长速率放缓。(3)由Pearson相关系数计算结果可知，降雨强度对水土流失量的影响程度要大于坡度对水土流失量的影响程度。坡度为3°、6°时，野外实地监测结果与室内试验结果基本保持一致，可见室内人工降雨试验适用于研究岩溶地区坡面产流特征。【结论】该研究可为桂北岩溶石山地区水土流失的防治和生态恢复提供理论指导和技术支撑。

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.

关键词

降雨 / 降雨强度 / 径流 / 水土流失 / 地形坡度 / 桂北地区

Key words

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

基金资助

国家自然科学基金项目(41867039)

南方石山地区矿山地质环境修复工程技术创新中心项目(CX2X2020002)

广西岩土力学与工程重点实验室资助课题(桂科能20-Y-XT-03)