Experimental Study On Rill Erosion Evolution Process On Loess Slope

Rill erosion is a transition stage of slope erosion to gully erosion.It appeared over the farmland soil and caused by the strong impact on agricultural production.The research of Mechanism and influencing factors of rill erosion process is the basis of slope soil erosion.It has an important contribution to governance soil erosion on slope and improve the agricultural production. To differentiate rill erosion process stages and explore the effect of impact factors in the analysis phase is one of the important measures to deepen the rill erosion mechanism.In this article, using the typical loessial soil, a series experiments were conducted, two different soil bins(5m×1m,10m×1.5m), on slopes of10°、15°、20°and25°, three rainfall intensity (1.5mm/min,2mm/min,1mm/min).Rill erosion stage was divided, the dominant factors in different stages was explored, rill flow velocity characteristics was analysed, meanwhile rill erosion of two kinds of soil was compared.The main research results are as follows:1) According to the characteristic of sediment concentration and rill form, the rill development processes were classified into four states, surface erosion, prototype of the rill, development of the rill and adjustment of the rill. Through carry on the analysis effects in different stages of rill erosion, about the slope gradient, slope length, rainfall intensity, sediment concentration erosion rate and so on, we know that the average sediment concentration would be bigger with the increase of slope gradient in the surface erosion stage. The duration of each stage will shorten along with the increase of rainfall intensity. The influences of the slope gradient in the average erosion rate depend on rainfall intensity. There is a linear relationship between total erosion and the biggest erosion for15minutes in the development stage.2) Stream flow contained sands is a motive force of the rill erosion.The analysis of flow velocity is particularly important. Slope flow velocity changes difference in the surface erosion and prototype phase is large.The appearance of drop needs certain critical slope flow velocity. Article’s innovation point lies in that rill flow rate of the rill development has a tendency to decrease with the increase of the slope gradient, which related to the furrow in space form. In the rill adjustment stage, the effect of slope length and the rainfall time on the rill flow was not significant.3) Compared with lou soil in yang ling, the sensitivity of the rainfall intensity about the loessial soil is smaller. The rill erosion would appear under greater rainfall intensity. Once the rill erosion started in the loessial soil slope surface the volume variations of loessial soil is strongly than lou soil. The duration time for stages is longer than lou soil. Loessial soil rill morphological changes slowly.This shows, the rill erosion stage division is used for deepen the mechanism research, more easy to clear the dominant factors influencing the rill erosion is helpful to determine the good time for prevention and treatment soil and water loss work caused by farmland rill erosion...