草带宽度对紫色土坡面细沟形态及水土流失特征的影响

Effect of Grass Strip Width on Rill Erosion Morphology,Soil and Water Loss Characteristics on Purple Soil Slope

为了解不同草带宽度对紫色土坡耕地水土流失的影响,以铺设四季青草带的紫色土坡面为研究对象,采用放水冲刷模拟试验,以裸坡为对照组,研究不同放水冲刷流量和草带宽度条件下坡面细沟形态变化和减沙减流效应。结果表明:(1)沟深随草带宽度增大呈先减小后增大趋势,而沟宽、沟长和沟宽深比均随草带宽度呈先增加后减小趋势;此外,沟宽、沟深和沟长随流量的增大而增大,而宽深比随流量的变化不明显;(2)当流量较小时(4 L/min),各坡面产流率和产沙率随着草带宽度的增大而减少,100 cm草带宽度的减流效益最高,为48.41%;当流量较大时(8 L/min),75 cm草带宽度的减流减沙效益最高,分别为20.07%和58.11%。(3)有草带的坡面产流产沙率、土壤侵蚀速率与沟宽、沟深呈极显著相关关系,相对于减流效益而言,草带对减沙效益更为显著。综上可知,草带能有效降低径流泥沙量,对紫色土坡耕地的水土流失具有较好的防治效果。

In order to understand the impacts of different grass strip widths on the soil and water loss of in purple soil sloping farmland,taking the Agrostis stolonifera grass strips paved on purple soil slope as the research objects,and through the indoor simulated scouring,we study the impacts of different grass strip widths and drainage scouring flows on the slope rill erosion morphology and the effects of sediment and flow reduction.The bare slope was used as the control group.The results showed that:(1)With the increasing of grass strip width,the rill depth decreased first and then increased,while the rill width,rill length and width-depth ratio showed a contrary tendency.In addition,the rill width,rill length and rill depth increased with the increasing of discharge,but the change of width-depth ratio was not obvious.(2)When the discharge flow was small(4 L/min),the runoff and sediment yield rate decreased with the increasing of grass strip width,and the outflow runoff decreased by 48.41%by for the 100 cm grass strip,which was the greatest.When the discharge was large(8 L/min),the 75 cm grass strip had the minimum runoff and sediment yield rate,which had the maximum reduction rate of runoff(20.07%)and sediment(58.11%).(3)Under interception of the grass strip,the runoff and sediment yield rate and soil erosion rate had significant correlation with rill width and rill depth.Compared with runoff interception and reduction,the grass strip had more significant impact on sediment interception and reduction.From these results we concluded that the grass strip was very efficient in reducing the runoff and sediment,and had a good control effect on water and soil loss of purple soil sloping farmland.