Experimental Study On Water Flow Characteristics Of Slope Under Vegetation Conditions

Vegetation has an important influence on s lope water flow.In order to study the influence of different vegetation coverage on the characteristics of slope water flow,this paper,relying on the scientific research project of the Yellow River conservancy research institute,adopted the method of simulation test and data analysis to analyze the influence of vegetation on slope water flow.The experimental data were divided into indoor test and field test,in which the indoor test was divided into three slope test,seven flow test and nine vegetation coverage test,and one slope test,three vegetation coverage test and five sand-water test with different sand-content.Field tests were divided into 1 s lope,6 f low rate and 6 ve getation coverage,totaling more than 240 gr oups of tests.The data of different combinations were processed,analyzed and compared,and the influence of vegetation coverage on t he characteristics of slope flow was discussed based on the theories of hydraulics and river dynamics.The main conclusions are as follows:(1)Vegetation has the effect of reducing the flow velocity of slope water.With the density of vegetation,the flow velocity of slope water gradually decreases;However,there is not a linear relationship between slope water flow velocity and vegetation coverage.The slope water resistance coefficient is similar to it,but increases gradually with the density of vegetation.For example,the froude number also decreases with the density of vegetation,that is,with the increase of vegetation coverage,the water flow on slope changes from jet stream to slow flow,and the vegetation coverage where the water flow pattern changes under different slopes is different.(2)Vegetation has the effect of reducing the velocity of sand-water on slope,which is similar to that of clear water.Along with the density of vegetation,the velocity of sand-water is consistent with that of clear water.The difference is that the velocity of sand-water on slope is significantly higher than that of sand-water.Vegetation has the function of intercepting the sand-bearing water and sediment on the slope.The denser the vegetation is,the greater the velocity reduction is,so that the role of intercepting sediment is more obvious.(3)On natural slopes(under field conditions),the relationship between slope water flow velocity and vegetation coverage change is not obvious,and the slope water flow velocity is basically stable and does not change regularly with the increase of vegetation coverage.This phenomenon can be obtained from the data of the five flow groups.Field under the condition of vegetation slope block sand effect is remarkable,test of small flow washout test only need 20% of vegetation coverage is effective,and with the increase of traffic,to achieve a good block sand,requires more vegetation,test showed that 60% of vegetation coverage is a threshold,the vegetation coverage of more than 60% under different traffic block sand effect can reach more than 90%,thus maintaining a good e ffect of soil and water conservation,vegetation coverage to meet the 60% threshold should be reasonable.The conclusion is of guiding significance to the practice of soil and water conservation.