Study On Spatial And Temporal Process Of Soil Erosion On Brown Earth Sloping Land During Natural Rainfall

Soil erosion evolution process and mechanism on the Slope is the focus on soil erosion research. which has a direct impact on the establishment and development of soil erosion prediction model. Under thel wild conditions, each rainfall erosion was on the basis of the last erosion, Erosion datum also was different. Studying on natural rainfall conditions for the rapid erosion evolution had a more realistic significance. This study was under the conditions of natural rainfall in the field, three different elevation runoff plots planted for a variety of REE for different layers. Then observed the process of sediment and runoff , studyed the erosion sediment source of slope and the evolution Process of erosion ways. The changing process of flow sediment load and soil erosion ratio was studied with time on the slope. According to the heavy rain erosion data of the trial at the same time, we studyed the slope erosion patterns and rill erosion of the temporal and spatial evolution in the process of rainstorm from the quantity. And Spots on the filter paper of natural rainfall raindrop was collected and measured, to analyze the characteristics of raindrops days of rainfall. the following main conclusions were made.(1) The raindrops characteristics of natural rainfallLow-intensity rainfall mainly composed of small raindrops, High-intensity rainfall mainly composed of larger raindrops. In the process of rainfall runoff yield and sediment Yield, The diameter of a few raindrops (D₅₀) Usually are greater than 3 mm, The distribution of raindrops comply to Best ModelF =1-exp[-(d/6.18i^0.29)ⁿ],n=3.055i^-0.092."D₅₀" has the power function with rainfall intensity,complying to the following equality: D₅₀ = 6.11i^0.31, Rainfall kinetic energy also has the power functionwith rainfall intensity, and power relation as e = 50.73i^0.23 was existed.(2) The rules of the runoff yield and the sediment yield on the slope under different rainfall patternIn the short-duration rain runoff process, a runoff show at the beginning of the rain, Production flow rate in the short duration of the slowdown, then reach the maximum. With the rainfall and the soil infiltration rate of slope. Slope sediment yield is under the impact of rainfall intensity, the change rules are similar to the runoff dynamic changes. Duringf the ordinary rain, Runoff and sediment yield rate are relatively small in the process of rainfall. In a Rainstorm , the process of rapid runoff has close relation with rainfall intensity. production flow rate shows the same trend with rainfall intensity. the rate of runoff, sediment yield rate and rainfall intensity in the peak is consistent on time.(4) The slope taking impact on the rill developmentThe slope take great impact on the rill development, the increase in the gradient, Rill develop more early, at the end of rainfall on August 8^th, the lower slope of 5°rill erosion develop to the Tb and Yb tracers, they are at the initial stage of development; the lower slope of 10°and 15°rill erosion develop to the Tb and Pr tracers, they are at the development stage and stable stage.(5) In Rainstorm process the changes of slope erosion and the relative changes of slope erosion in the spaceIn the process of storm runoff and sediment ,the rapid erosion is relatively larger, with the emergence of the peak storm, the erosion rate have also appeared high peaks in tracing areas, the tracer contribution rate of the erosion process in a heavy rainstorm was relatively stable; Rill fully in the development of 15°slope of the A, B, and C, and D, the relative erosion volume: 82.5%, 6.9%, 3.3% and 7.3%, respectively, the ratio of erosion : 1:0.08:0.04:0.09.(6) Revealing the presses of flow sediment load and soil erosion ratio and their relationshipDuring the rainfall, the sediment concentration of each wild plot decreased from the upper to thebottom.The soil erosion ratio peak of each section of the slope and the instaneous rainfall intensity were corresponding with time; The soil erision ratio and the flow sediment load complied to the following equality: Dr =aSw^b; During the whole continuous rains, power relation as Dr =aSw^b was listed between erosion ratio and flow sediment load.