Erosion Study On Pisha Sandstone Slope Under Simulated Rainfall Condition

Pisha sandstone areas in the middle reaches of the Yellow River exist serious water and soil erosion, which has caused bad influence to the ecological environment. However, current research about erosion mechanism on this region is not enough, especially lacks rainfall simulation experiment data. What's more, the region's soil and water conservation measures have been old-fashioned, few chemical materials measures applied.First of all, in the indoor simulated rainfall conditions, the erosion rule of slope rainfall in Pisha sandstone region was studied from the aspects of rainfall intensity and slope gradient and the coverage of vegetation. Then through regression analysis, water erosion forecast model about Pisha sandstone slope was established. Secondly, by using indoor simulated rainfall experiment and outdoor runoff scouring experiment, the effect on increasing resistance to water erosion of Pisha sandstone by a novel hydrophilic polyurethane (W-OH) was examined. The main conclusions are the following:1) The permeability of Pisha sandstone is very poor. Within a rainfall, the infiltration water accounts for only 10%?15% to the total rainfall amount. With the increase of rainfall time, the runoff rate tends to be stable, basically equal to the rainfall intensity. The sediment yield is affect by different factors:the influence of rainfall intensity> vegetation coverage> slope.2) The vegetation coverage in Pisha sandstone has a more significant effect to sediment reduction than to runoff reduction. In different conditions, runoff reduction rate is about 20%, however sediment reduction rate is about 70%. In addition, the benefits of vegetation coverage to sediment reduction are particularly affected by rainfall intensity. If you want to get an ideal effect of erosion reduction, the greater rainfall intensity must be corresponding higher vegetation coverage.3) By regression analysis. Pisha sandstone slope erosion sediment shows a good linear relationship with slope and vegetation coverage, and has a good power function relationship with the rainfall intensity. Then water erosion forecast model about Pisha sandstone slope is established with time, rainfall intensity, slope, and vegetation coverage.4) After spraying W-OH, a steady and solidification layer is formed on the Pisha sandstone surface, which could play a role in isolation of water and Pisha sandstone and speed up the flow grooming by improving slope smoothness. Indoor rainfall conditions, erosion reduction of W-OH has a significant effect, and the sediment reduction rate under different conditions is more than 98%. The same to outdoor conditions, the sediment reduction rate is even more than 99.5% in two types of slope.