不同雨强对我国西南喀斯特山区土壤侵蚀影响的模拟研究

Laboratorial Simulation of Different Rainfall Intensity Influence on Soil Erosion in Southwest Karst Area,China

选取我国西南喀斯特地区作为研究区域,通过资料查询、野外考察,设计加工满足该区域雨强范围的针管式人工降雨装置,在不同地表覆盖情况下,针对不同雨强对土壤侵蚀的影响进行了16场室内模拟试验,结果表明(1)坡面径流率在产流后180～300s之后保持稳定。随着雨强的增大坡面径流率增大,同雨强时坡面覆盖的植被或岩石均有明显的减流效果。(2)坡面输沙率变化可分为快速增大、迅速减小、增大、缓慢减小和趋于稳定5个阶段。坡面平均输沙率均随雨强的增大而增大。同雨强时坡面覆盖的植被或岩石的减沙效果显著。(3)坡面总径流量随雨强的增大而增大,同雨强时裸地坡面总径流量最多。裸地、植被覆盖(70%)地、植被-裸岩覆盖(70%～60%)地坡面总侵蚀量随雨强的增大而增大。裸岩覆盖(60%)地坡面总侵蚀量随坡度的增大而先增大后减小,在60～114mm/h之间存在土壤侵蚀的雨强转折点。同雨强时裸地坡面总侵蚀量最大,植被或岩石覆盖的减沙量均在71%～88%之间。

This paper chooses the karst area in southwest China as the research region. By the analysis of material and fieldwork,an equipment of imulated rainfall was designed which could fulfill the range of rainfall intensity in this area. 16 processes of soil erosion simulation tests were done by intercombination of different rainfall intensity to different covered soil.Results are as follows：（1） Runoff ratio kept steady after 180~300 s,and it increased with the increase of rainfall intensity,the covered vegetation or rocks have a prominence function of decrease runoff when rainfall intensity is changeless. （2） The change trend of transport rate of sediment yield could be divided into five periods： increase rapidly,decrease fast,increase,decrease and keep steady. Transport rate of sediment yield increased with the increase of rainfall intensity,and the covered vegetation or rocks have a prominence function of decrease it when rainfall intensity is changeless. （3）Total runoff increased with the increase of rainfall intensity,and it was maximum when rainfall intensity is changeless. The total sediment yield increased with the increase of rainfall intensity of bare soil,vegetation-covered （70%） soil and vegetation-rocks covered （70%~60%） soil,and it increased at first then decreased with slope of rocks-covered（60%） soil,and there is turning point between 60 mm/h and 114 mm/h for soil erosion. With the same rainfall intensity,the total sediment yield of bare soil was maximum and the decreasing sediment yield of covered vegetation or rocks was between 71% and 88%.