紫色土区不同芒萁盖度下的减流减沙效应

本研究以人工降雨为条件,设置径流小区,布设不同的芒萁盖度,揭示紫色土区不同芒萁盖度下的产流产沙规律,探究地表水的入渗强度,揭示芒萁在水土保持方面的效益。结果表明,不同芒萁盖度下的产流时间随着芒萁盖度的升高而延长,当芒萁盖度大于60%时,初始产流时间曲线斜率变缓,芒萁盖度在10%~50%时,初始产流时间变化幅度较小。紫色土坡面产流量随着芒萁盖度的增大而减小,二者之间存在显著的负相关。但芒萁盖度在50%以下时,对径流量减少没有显著的影响,当芒萁盖度>50%时,产流量减小显著且处于稳定状态。当芒萁盖度>50%时,坡面产沙量会达到稳定值,且变化幅度较小,说明在紫色土坡面芒萁覆盖度达到50%就能有很好的水土保持作用。而关于坡面入渗率方面,芒萁盖度在50%~60%间坡面入渗强度曲线较为接近,可能由于在50%~60%间存在盖度的临界值。

Effect on Reduction of Water Flow and Sediment with Different Coverages of Dicranopteris dichotoma in Purple Soil Area

The runoff plots with different coverages of Dicranopteris dichotoma were set up for study with the artificial rainfall as the condition.It was summarised the law of runoff and sediment yield under different coverages of Dicranopteris dichotoma in purple soil area,explored the infiltration intensity of surface water,and revealed the benefit of Dicranopteris dichotoma in soil and water conservation.The result showed that,the flow-generation time extended with the increase of coverage of Dicranopteris dichotoma.When the coverage was more than 60%,the curve slope of the initial flow-generation time slowed down,while when the coverage was between 10~50%,the range of flow generation time was small.The flow rate of purple soil slope decreased with the increase of the cover of Dicranopteris dichotoma,forming the significant negative correlation between each other.However,when the coverage of Dicranopteris dichotoma was less than 50%,it had no significant effect on runoff reduction,while when the coverage of Dicranopteris dichotoma was more than 50%,the runoff decreased significantly in a stable state.When the cover degree of Dicranopteris dichotoma was more than 50%,the sediment yield of the slope reached the stable value,with small change range,indicating the good effect of soil conservation when the cover degree of Dicranopteris dichotoma reached 50%on the purple soil slope.Regarding to the slope infiltration rate,the penetration intensity curve was relatively close when the cover of the Dicranopteris dichotoma between 50%to 60%,which may be due to the critical value of the cover between 50%to 60%.