| Karst Trough Valley area exists binary space surface underground geological structure,soil erosion is through the earth’s surface and underground erosion at the same time,due to human to destroy the natural environment at the expense of unreasonable activities,led to the karst trough valley area soil difficulties,shallow soil layer and bedrock exposed,water storage capacity is low,speed up the process of rocky desertification in the region,the ecological environment is fragile.In addition,there are also typical vertical/horizontal slopes in karst areas,which cause different angles between rocks and slopes,causing different degrees of soil erosion and complicating the mechanism of sediment yield on slopes.Therefore this study You Yang County longtan karst trough valley area in chongqing as the research object,through field investigation of karst trough valley area of soil physical and chemical properties and environmental factors as the simulation research basis,by means of indoor simulated scour,in different slope,the strength of scour,rock and slope Angle as a variable factor,this paper discusses the karst trough valley area of slope surface erosion characteristics of the runoff and sediment yield in the underground and surface water allocation mechanism,revealed the different conditions of karst trough valley slope surface soil erosion change process,for the karst trough valley area of soil and water loss and soil erosion model provides the theory basis for the establishment of the,main conclusions are as follows:(1)In the case of different rock inclination Angle and slope conditions,the variation trend of surface yield flow with scour time generally shows a trend of first increasing,then decreasing,and finally stabilizing,which generally occurs within a period of 6-8 minutes.Surface runoff is positively correlated with erosion intensity and slope,and increases with its increase.Under the same slope and scouring strength,the surface yield of 2% porosity is slightly less than 0% porosity.At 2% porosity,the underground production flow fluctuates with the erosion duration,which decreases with the increase of slope and increases with the increase of flow.Under the condition of 0% porosity,the order of average surface yield at different included angles was150°>120°>60°>30°>90°>180°.Under the condition of 2% porosity,the order of average surface yield at different included angles was 150°>120°>90°>30°>60°>180°.Under the condition of the included Angle between the same rock and slope,0% of the surface runoff was slightly more than 2%.Under the test condition,the underground production flow increased with the increase of the flow,but did not change significantly with the slope.In the case of 2% porosity,the order of the average underground production flow at different included angles is30°>90°>60°>180°>120°>150°.With the increase of rock dip Angle,the surface runoff coefficient also increases.Under different porosity,the surface runoff increased first and then decreased slightly with scouring time,and then tended to be stable.(2)The surface sediment yield changes with the scouring duration and generally shows a trend of first increasing and then decreasing fluctuations,and increases with the increase of slope and flow.Under the conditions of greater scouring intensity and slope,The trend is more obvious.The surface sand yield of 2% fissure degree is less than 0% of the surface sand yield.Under the conditions of the greater the erosion intensity and the larger the slope,the loss is more obvious,and the amount of underground loss is more.Comparing 0% fissure degree and 2% fissure degree,under the surface sand production index,the 2% trend is relatively more stable and the fluctuation is smaller.Under the condition of 0% fissure degree,the order of the average surface flow rate at different included angles is 60°>120°>30°>90°>180°>150°.Under the condition of 2%fissure degree,the order of average surface sediment yield at different angles is150°>30°>120°>90°>180°>60°.Under different fissure degrees,the surface sediment yield fluctuates and decreases with the scouring duration,and the surface sediment yield varies greatly under different rock and slope angle conditions.(3)The sediment content of surface water flow generally shows a trend of gradual fluctuation and decrease with the scouring duration.Under the condition of 0% fissure degree,the sand content of the surface water at different angles between the rock and the slope is in the order of 120°>60°>30°>90°>180°>150°.Under the condition of 2% fissure degree,the sand content of the surface water at different angles between the rock and the slope is in the order of150°>90°>30°>180°>120°>60°.Under different angles,the variation range of surface water sediment content at 2% is greater than 0%,but its average sand content is smaller.The sand content of surface water is not significantly affected by the scouring flow,but is more obviously affected by the slope,and increases with the increase of the slope.Under 0% and 2% fissure degrees and different combinations of rock and slope angles,there is a good positive power function correlation between surface discharge and surface sediment yield,and the relationship between the two is significant,and the surface sediment yield Increase with the increase of surface production flow.Under the condition of 0% fissure degree,when the angle between the rock and the slope is 30°,90°,120°,180°,the relationship between the two is extremely significant;under the condition of 2% fissure degree,the angle between the rock and the slope When it is30°,60°,120°,and180°,the relationship between the two is extremely significant.It shows that under the conditions of 30°,120°,and180°,the surface production flow can better reflect the surface sand production.Under the conditions of 0% and 2% fissure degree,when the rock and the slope are at any of the above-mentioned angles,the linear relationship between the flow rate and the sediment yield is extremely significant,and the linear function and the intercept of the y-axis tend to be infinite.Nearly 0,indicating that during the experiment,when there is no runoff on the surface,there will be no sand on the surface. |
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