The Study On The Effect Of The Soil Erosion Resistance In Soil Alternate Drying-wetting And To The Sensitivity Of The Rill Evolution

Rill erosion is an important part of the soil erosion, the soil erosion have a sharp increasewhen the rill occurred in slope. We have the research of the rill evolution in flume scouringexperiment as the object of Yang Ling loess soil、Peng Yang Pill loess soil and Zhi Dan Pillloess soil. The time of the rill transfixion、sediment rate and the ratio of depth to width can bereflect the degree of difficulty rill evolution。We put forward the comprehensive sensitivityindex of the rill evolution to reflect the degree of difficulty of the rill development through theanalysis. it can be a good response of rill evolution. We study the soil bulk density、anti-erodibility、anti-scourability in the process of the soil alternate drying-wetting through thesimulation of soil box.The result have been compared with the soil including the roots.Analysis the impact of the soil alternate drying-wetting to the rill evolution, we obtained thefollowing conclusions:(1) The flume scouring experiment in slope shows that: from Yang Ling loess soil、PengYang Pill loess soil and Zhi Dan Pill loess soil, the time of the rill transfixion becomes longer,the Yang Ling loess soil is2times than Peng Yang Pill loess soil and10times than Zhi DanPill loess soil. The average of sediment rate of Zhi Dan Pill loess soil is14times、13times toYang Ling loess soil and Peng Yang Pill loess soil，and the ratio of depth to width becomeslarge. Through the analysis of the time of the rill transfixion、sediment rate、the ratio of depthto width,we put forward the comprehensive sensitivity index of the rill evolution, reflectingthe degree of difficulty of the rill evolution, the value is between0to100.The comprehensivesensitive index value is smaller, the rill evolution is not sensitive, the value is higher, the rillevolution is more sensitive.(2)The comprehensive sensitive index of rill evolution is increased as the slopeincreasing, the rill evolution become easier. The7slope may be the key slope of the time ofthe rill transfixion in the experiment slope. The average of sediment rate is from fluctuationincreasing to fluctuation decreasing as the increasing of the slope. The ratio of depth to widthbecomes large as the slope increasing. It is wide and shallow shape when slope is small,narrow and deep shape when large. The rill development becomes easy as the roughness occurs in slope. It is not sensitive of rill evolution in different roughness.(3)The soil bulk density slowly increases as the increasing of the soil alternatedrying-wetting, soil consolidation is from fast to slowly. The anti-erosion coefficientincreased13times as the soil alternate drying-wetting. The soil alternate drying-wetting canimprove the soil anti-erodibility. The anti-erosion coefficient of the soil with crop roots is11times than the alternate drying-wetting soil. The crop roots have a big inflation to the soilanti-scourability. The crop roots can not be ignored in control of the soil erosion.(4) Te soil disintegration rate is slowly decreasing as the soil alternate drying-wetting.The soil alternate drying-wetting is limited to the soil disintegration as time increases. All soilparticles eventually break into the water. The crop roots in the soil reaches a certain level(0.0065g/cm3), soil disintegration rate is very low. The anti-erosion of roots is very obvious.(5) The comprehensive and sensitive index of the soil evolution is different in differentsoil、slope、roughness、bulk density. In all the test of the paper, the maximum value of theindex is the soil of the bigger bulk density, the smaller slope, the minimum value of the indexis the soil of the smaller bulk density, the bigger slope. the rill evolution is insensitive.Therefore, in the control of the rill erosion, reducing the slope and increasing the bulk densitycan reduce the occurrence of rill erosion.