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地形因子在坡耕地土壤侵蚀过程中起着重要作用,重庆市紫色土坡耕地的地形具有坡度陡、坡长短的特点。该文采用野外人工模拟降雨方法研究了不同地形因子条件下紫色土坡耕地的产流产沙特征,结果表明:(1)径流输沙率过程与雨强变化表现为具有一定相关性和一致性的动态响应过程,随着坡长增加,产流量增加很快,4m坡长的产流量约为2m坡长的2.7倍;在20.6°坡度以下,随着小区坡度增大,产流量以接近直线的关系增长,在20.6°时产流量增加到最大。(2)相同坡长小区不同降雨条件下的产沙量存在一定波动性,相同坡度和降雨下4m坡长小区的产沙量约为2m小区的1.3倍,经推导,4m坡长坡耕地径流输沙率大致为2m坡长的0.48倍。(3)在相同坡长条件下,坡度与土壤流失量可拟合为二次多项式关系,紫色土坡耕地土壤侵蚀的临界坡度约为22°。研究成果可为重庆市三峡库区坡耕地水土流失量预测和坡耕地综合整治提供参数和依据。
Topographical factors play an important role in the process of soil erosion on sloping arable land. The topography of purple soil sloping arable land in Chongqing has the characteristics of steep slope and long and short slope. This paper studied the characteristics of runoff and sediment yield of purple soil sloping farmland under different topographical factors using artificial simulated rainfall in the field. The results show that: (1) The process of runoff and sediment transport has some correlation and consistency with the change of rainfall intensity Dynamic response process, with the slope length increases, the flow rate increased rapidly, 4m slope length of the flow rate of about 2m slope length of 2.7 times; below 20.6 ° slope, with the slope of the district to increase the flow to near-line Relationship growth, the flow rate increased to 20.6 ° maximum. (2) There is a certain fluctuation of sediment yield under different rainfall conditions for the same slope length. The sediment yield of the 4m slope long area under the same slope and rainfall is 1.3 times that of the 2m plot. According to the deduction, Sediment transport rate is roughly 0.48 times the 2m slope length. (3) Under the condition of the same slope length, the slope and the amount of soil loss can fit the quadratic polynomial relationship, and the critical slope of soil erosion on purple soil slope is about 22 °. The research results can provide the parameters and basis for the prediction of soil and water loss and the comprehensive improvement of slope farmland in the Three Gorges Reservoir area in Chongqing.