短历时强降雨对典型喀斯特坡耕地侵蚀产沙的影响

探索短历时强降雨对典型喀斯特坡耕地侵蚀产沙的影响,为喀斯特区坡耕地应对极端天气的水土流失防治提供理论依据。研究采用人工室内模拟降雨试验的方法,对喀斯特坡耕地侵蚀产沙特征在短历时强降雨作用下的影响因素开展研究。结果表明:(1)短历时强降雨导致喀斯特坡耕地地表输沙模数和产沙量随降雨强度的增大而增大,而地下输沙模数和产沙量与降雨强度无明显变化规律,坡耕地土壤侵蚀以地表为主。地表产沙临界雨强为30～50 mm/h。(2)坡度增大时地表产沙比重大于地下产沙比重,地表土壤侵蚀以地表为主。产沙比重发生转折的坡度值为15°～20°。70 mm/h降雨强度和5°坡度下,降雨强度对地下土壤侵蚀可能存在"负效应"。(3)喀斯特坡耕地侵蚀产沙特征与降雨强度和坡度密切相关,但降雨强度因子起主导作用。强降雨主要影响地表土壤侵蚀,因此,对喀斯特坡耕地土壤侵蚀治理应以地表为主。研究结果有助于深入了解短历时强降雨对喀斯特坡耕地土壤侵蚀的影响,为对喀斯特坡耕地应对极端天气和水土流失防治以及维持生态环境健康持续发展提供理论依据。

Effects of Short-Duration High-Intensity Rainfall on Erosion and Sediment Yield of Typical Karst Slope Farmland

This study explored the impact of the short-duration high-intensity rainfall on the erosion and sediment yield of typical karst slope farmland. The results would provide theoretical basis for the monitoring and preventing of extreme weather and soil erosion in slope farmland of karst area. The artificial indoor simulated rainfall experiment was conducted to study the erosion and sediment yield characteristics of karst slope farmland under the short-duration high-intensity rainfall. Results showed that:(1) Under the short-duration high-intensity rainfall, the surface sediment transport modulus and sediment yield of karst slope farmland increased with the increase of rainfall intensities, but there was no obvious change in the under-ground sediment transport modulus and sediment yield. The soil erosion of slope farmland was dominated by the surface, and the critical rainfall intensities of surface sediment yield were between 30~50 mm/h. (2) The proportion of surface sediment yield was greater than the underground when slope increased, and soil erosion was dominated by the surface. The transition slope of sediment yield was between 15°~20°. At 70 mm/h rainfall intensity and 5° slope, rainfall intensity might have a "negative effect" on underground soil erosion. (3) The characteristics of erosion and sediment yield on karst slope farmland were closely related to rainfall intensities and slope, but the rainfall intensity factor played the leading role. High-intensity rainfall mainly affected surface soil erosion. Therefore, the soil erosion control of karst slopes farmland should be dominated by the surface. This study is helpful to understand the impact of short-duration high-intensity rainfall on soil erosion of karst slope farmland, and to provide theoretical basis for coping with the extreme weather, controlling soil erosion, maintaining the healthy and sustainable development of the ecological environment in karst slope farmland.