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采用人工模拟降雨法,分析了紫色土丘陵区坡耕地坡面侵蚀过程地表石砾化、土层厚度变化及影响因素,利用建立的流失土层厚度计算方程对重庆地区不同土地利用类型流失土层厚度进行了分析。研究表明:(1)在降雨前、3次降雨后、6次降雨后,小区地表石砾覆盖度分别为1.5%,2.4%和12.2%,地表石砾覆盖度与累积产沙量正相关,在相同产沙量条件下,后期降雨侵蚀产沙造成的石砾化程度更为显著;(2)在模拟降雨前期,随着降雨量增大坡面流失土层厚度增加很快,4场降雨后降雨量增大导致的流失土层厚度增长率减少;不同地形因子组合下,累积雨量与流失土层厚度间存在较好的线性关系;(3)重庆地区无措施裸露坡耕地年均流失土层厚度为4.479 mm,大于年均成土厚度,作物覆盖顺坡耕地、作物覆盖横坡耕地、植物篱坡耕地、作物覆盖水平梯地、林地和荒草地年均流失土层厚度分别为1.931,0.728,0.533,0.041,0.001,0.079 mm,均小于年均成土厚度;重庆地区流失土层厚度大小为:渝东南地区>渝中部区>渝东北区>主城区>渝西地区,研究可为重庆市水土保持分区防治提供理论指导。
Using artificial simulated rainfall method, the authors analyzed the surface rockblown, soil thickness changes and influencing factors during slope erosion in sloping farmland in purple soil hilly region. By using the established equation of lost soil thickness, Thickness was analyzed. The results show that: (1) Before the rainfall, after 3 rainfalls, the surface gravel coverage of the plot is 1.5%, 2.4% and 12.2% respectively after 6 rainfalls. The surface gravel coverage is positively correlated with the cumulative sediment yield, Under the same conditions of sediment yield, the degree of gravelification caused by later rainfall erosion and sediment yield is more significant. (2) In the early stage of simulated rainfall, the thickness of soil loss on the slope increases rapidly with the increase of rainfall, There was a good linear relationship between the accumulated rainfall and the thickness of the lost soil layer under different combination of topography factors. (3) The average annual loss of bare soil on bare slope in Chongqing The thickness of the layer is 4.479 mm, which is larger than the average annual soil thickness. Crop cover slope farmland, crop cover slope sloping farmland, hedgerow slope farmland, crop cover level terrace, forestland and grassland annual loss soil thickness are 1.931, 0.728,0.533,0.041,0.001,0.079 mm, which are less than the annual average thickness of soil forming. The thickness of soil loss in the area of Chongqing is: southeastern Chongqing area> Yuzhong area> Chongqing northeast area> main city area> western Chongqing area, Soil and Water Conservation in Chongqing Municipality to provide theoretical guidance for prevention and treatment.