| The Pisha-sandstone is a kind of low di agenesis.It has high porosity,loose internal structure,poor stability,strong hydrophilicity,and is vulnerable to water erosion.Coupled with the deterioration of the local natural environment and the development of improper human activities,the soil erosion in the area is extremely serious and becomes the main material source of coarse sand in the Yellow River.This paper takes the red Pisha-sandstone of Zhungeerqi in Ordos,Inner Mongolia,as the research object.Through the indoor scour t est,the er osion patterns,runoff characteristics and sand production law of t he slope of the Pisha-sandstone are analyzed and studied under different slope and flow conditions.The resul ts indicate that:1.The slope erosion of the Pisha-sandstone is mainly rill erosion under erosion conditions.In the process of development,fine rills will be bent,bifurcated,converged and merged,and finally a banded rill network distributed along the length of the slope wil l appear.2.During the process of Pisha-sandstone erosion,t he flow st ate of the thin layer on the slope belongs to the rapids flow in the laminar flow,and t he generation of the erosion rill is not only affected by F_r,but also closely r elated to R_e.3.According to the grey correlation analysis of the dynamic factors of sand production on the slope of Pisha-sandstone,it can be known that energy slope and single width flow ar e the main influencing factors of slope erosion.A two-factor model for the erosion and erosion rate of the slope of Pisha-sandstone is established by usi ng Matlab software.4.Based on WEPP soil erosion prediction model,t hrough the analysis of the main i nfluencing factors of Pisha-sandstone rill erosion,the erodibility parameters and critical shear stress of the Pisha-sandstone are obtained under erosion conditions:The parameter of the erodibility of the Pisha-sandstone is only 0.002 kg/(N·s)when the slope is 5°,and the erodibility parameter of the Pisha-sandstone of the slope above 10°is 0.0482 kg/N·s.Therefore,the slope of the sandstone of l ess than 5°is di fficult to be eroded.5.A mathematical model of fine sand-channel erosion and sedi ment yield in pluton-bearing Pisha-sandstone with slope,water flow shear,and single-width flow was established under erosion conditions.The calculated results of the model are in good agreement with the measured ones,which shows that the model has good prediction results for t he fine-gully erosion of the pluton Pisha-sandstone under erosion conditions,and can predict the runoff er osion of the pluton Pisha-sandstone in this area. |
