紫色土丘陵区坡耕地坡面侵蚀响应特征研究

Study on Response of Slope Erosion Characteristics in Purple Hilly Region

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 simulated rainfall method,this paper analyzed the sloping surface gravel,soil layer thickness change process and its influencing factors in purple hilly region,and the thickness of soil loss using the established equations on the different land use types in Chongqing.The results showed：（1） The rates of surface gravel coverage before the precipitation,after 3 times precipitation,after 6 times precipitation were 1.5%,2.4%,12.2%.Surface gravel cover had the positive correlation with the accumulation of sediment yield.It was more significant degree that the later rains sediment yield caused gravel during slope land erosion in the same conditions.（2） In the period of prophase rainfall,the loss thickness of soil layer caused by soil erosion increases rapidly with the rainfall increased,and the rise rate of loss thickness of soil layer which caused by rainfall increased reduce after 4 times rainfall.There was a good linear relationship between cumulative rainfall and loss thickness of soil layer at different topography factors combination.（3） The average loss thickness of soil layer in bare sloping land was 4.479 mm which hadn＇t any defend measures,and greater than annual thickness of pedogenic.The annual loss thickness of soil layer on downslope arable land with crop cover,cross farmland with crop cover,farmland with hedgerows,the level of terrace land with cover crops,woodland and grassland were 1.931,0.728,0.533,0.041,0.001,0.079 mm,and both of them were less than thickness of pedogenic.The loss thickness of soil layer in different zones of Chongqing： southeast of Chongqingcentral part of Chongqingnortheast of Chongqingmajor city of Chongqingwestern part of Chongqing.The results provided theoretical guidance for prevention and control soil erosion for Chongqing area.