| In Huaibei area,the slope land of plain accounts for 68%,the ground height difference is large,the fluctuation is many,and the soil erosion area is 470.78km~2.The crop distribution in this area is mainly drought.It is an important commodity grain cotton oil production base in Anhui Province,in which the peanut planting area accounts for more than 40%of the whole province.Under this background,it is of great significance to study the rainfall erosion law in this area.The experiment was carried out in the artificial rainfall experimental field of Wudaogou hydrological experimental station,with4 kinds of slope and 3 kinds of rainfall intensity.The experiments of runoff and sediment yield of peanut in different growth stages of yellow fluvo aquic soil bare soil and Shajiang black soil were carried out respectively.According to the runoff and sediment yield and infiltration process of slope,as well as the change law of hydrodynamic parameters,The conclusions are as follows:(1)The initial runoff generation time and stable runoff generation time of bare soil decrease with the increase of rainfall intensity and slope.At the beginning of rainfall,the slope flow increases rapidly until stable runoff generation.6°is the critical slope of rainfall erosion of yellow tide soil.(2)The water content of soil within 0.5 m depth is more sensitive to rainfall.The greater the soil depth,the smaller the change degree.Infiltration is an important factor affecting rainfall erosion of yellow fluvo aquic soil.(3)Under the condition of bare soil,the velocity of surface flow is closely related to slope and discharge.Under the experimental conditions,the flow pattern of slope flow is laminar flow.Re increases with the increase of slope and rainfall intensity.There is a critical slope between 6°and 9°which makes the slope flow change from slow flow to rapid flow.The resistance coefficient decreases significantly with the increase of rainfall intensity and is closely related to Froude number.(4)The results showed that vegetation coverage had significant effect on the initial runoff yield time,and the stable runoff yield at different growth stages was very close under the same slope.Under the condition of different rainfall intensity and vegetation coverage,the total runoff is the largest when the slope is 6°and the benefit of runoff reduction in mature stage is significantly higher than that in flowering stage,and the benefit of runoff reduction is positively correlated with leaf area index.(5)With the increase of slope,the sand blocking effect of vegetation is weakened,and the stable sediment yield rate of bare soil is close to the same.The benefit of sediment reduction in mature stage is significantly greater than that in flowering stage.The total sediment yield increases linearly with the total runoff in different growth stages.(6)During the whole rainfall process,the soil water content of the bare soil of Shajiang black soil only changed significantly at the shallow buried depth,but at the flowering stage and mature stage,the soil moisture content at the depth of 10-150 cm changed in different degrees,forming a layered runoff generation mechanism of surface soil full and deep soil over infiltration.(7)Under the experimental conditions,the flow pattern of slope flow is laminar flow,and the resistance coefficient increases significantly under vegetation coverage.The benefit of increasing resistance is positively correlated with rainfall intensity at flowering stage and mature stage,which decreases first and then increases with the change of slope,and reaches the minimum value at 9°. |
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