Mechanism Analysis Of The Gravitational Erosion From The Gully Wall On The Loess Plateau

Gravitational erosion is the main format of erosion on the Loess Plateau of China. The study on the mechanism of the gravitational erosion is of great importance. A series of model experiments in various initial dimensions were operated to simulate the process of gravitational erosion. In this study, the accuracy of the equipment was analyzed firstly, then the relationship between the gully density and the gravity erosion was discussed, thirdly the influence of the interface configuration of the gravitational erosion on the security of the erosion models was discussed. The conclusions can be summarized as follows:(1) The system reliability and availability of the "MX-2010-G topography instrument" was discussed. It turned out that it had high efficiency and precision by different operators, and it was also easily to operate. The development of the system in future should be impersonal and automatic, which will greatly improve the accuracy and efficiency of the system.(2) The thesis analyzed the relationship between the gully density and erosion process. Firstly, in different rainfalls, the gully density showed cyclical state with the double peak phenomenon; secondly, the suddenly increase of the gully density will lead to the gravitational erosion. However, gully density can only be used as an index of gravitational erosion to predict the occurrence of gravity erosion.(3) There are mainly two types of the interface configuration of slide and collapse, circles and plane. The proportion of the plane is always more than the circles. Results show-that the increase of the slope height and the slope gradient will lead to the erosion with the circles interface configuration. However, the volume of the gravity erosion with circles interface configuration is smaller than the plane ones. Moreover, the increase of the proportion occurred frequency circles surface will reduce the stability of the whole region and increase the risk of gravity erosion, but it has no significant influence on the whole volume of the gravity erosion.(4) The existence of the gullies has a great influence on the sediment concentration. In the earlier stage of the model tests, gullies are the main source of the sediment. The correlation between the gully density and the sediment concentration i^fine, and the sediment movement aggravates the gully development at the same time. Moreover, in the later period of the rainfall simulation, the gullies just play a role as the ravines of. the sediment transport, and the relationship between the two factors is not very obvious.