Study Rill Flow Characteristics And Erosion Mechanismon On Loess Slope

Rill erosion is erosion process after overland flow collection, And its movement have larger gap with overland flow, The rule is similar to the river sediment evolution rule, by comparison, Rill flow have characters of gully bed slope is bigger、Runoff depth shallow and the bed surface morphology evolution is more quickly. So further study of rill flow play a crucial role on the loess plateau surface erosion. In this article, through indoor simulation test, Studying six slope(2°、4°、6°、8°、10°、12°)and five discharge(8L/min、16L/min、24L/min、32L/min、40L/min) combination scouring test condition of rill flow dynamics characteristics、function and Formation mechanism of rill flow drop pit and rill flow soil erosion mechanism on Loess slope surface. Main research results included:(1) Rill flow average velocity, Water cross section width have Power function relationship with discharge, The influence of slope is smaller, The reason for this is likely to flow intensity and bed surface in the form of restriction on each other; Froude number increases with the increase of runoff flow, Vary condition Froude number less than 1, Show that Loess rill flow belong to the category of subcritical flow; Reynolds number increase with the increase of slope and runoff flow, Its value vary from1061 to 4802, belong to turbulent flow, Resistance coefficient increases with the increase of the slope and no relationship with Reynolds number, Along with the increase of the intensity of rill flow,Bed surface morphology development significantly, It means flow dissipation capacity increase,Resistance coefficient vary from 0.16 to 1.45.(2) ratio of average space and average depth decrease with the increase of slope, Indicates that with the increase of the slope drop pits development more mature, And discharge are less influence on both; drop pit development coefficient have positive relationship with slope, its value in the1.01<SP<1.14; and it have positive relationship with manning resistant coefficient, It meaning fellow of the drop pit development more mature, Water resistance more developed, Energy dissipation is more intense. Under the same slope, The energy dissipation efficiency present a tendency of linear decrease with the increase of the discharge; The energy dissipation efficiency and Drop pit development coefficient present a tendency of power function increase with the increase of the slope.The energy dissipation efficiency value in 87.28%~98.58%.(3) soil detachment rate have power function relationship with discharge and slope, And slope influence more; Different types of non-dimensional soil detachment rate have zoned phenomenon with non-dimensional flow velocity, Show that soil erosion have other influence factors except diameter ofparticles, And non-dimensional soil detachment rate with non-dimensional shear stress double-log function have A linear increase relationship; Soil erosion rate increased with the increase of unit weight of water runoff energy consumption, Run off energy consumption and soil detachment rate both increase with slope increase; Soil erosion rate have a trend of increase power function with the increase of down hole development coefficient, and the soil erosion rate with L/H value increases the power function decreasing trend, Show that bed surface morphology increasingly more complex and drop pit development increasingly more mature, the soil erosion is more intense.