Simulation Of Gravitational Erosion In The Loess Gully Wall Based On Various Rainfall Condition

Gravitational erosion is an important type of soil erosion in the Loess Gully area. It has a huge impact to geological disasters, soil erosion and sediment transportation. This study carefully analysis other researcher’s finding, including torrential rainfall, gravitational erosion simulation mechanism of gravity erosion in Loess Plateau. In consideration of Loess Plateau’s unique geographical environment, we analysis the regional natural conditions based on survey and relevant literature theory and method study. Then, the gravity erosion rainfall simulation system is established. Using the rainfall simulation systems, the topography meter, and other equipment and technology, make a thorough inquiry to the gravitational erosion process from the perspective of rainfall intensity, rainfall duration, gradient, and other factors. During the experiment, we carry out all-round observation contains the process of gravitational erosion simulation, the amount of runoff and sediment and other content. Based on the observe data, draw the following main results:(1) Proposed a method, which can observe the form of erosion failure surface. Divide the erosion failure surface into four different types:linear, Convex curve, upward Concave arc and downward concave arc. Four types erosion failure surface present a different ratio. The upward Concave arc erosion process gain a high percentage in occur frequency and the ratio of gravitational erosion. Linear type erosion process occurs frequently with a small scale. Convex curve type erosion process has a less ratio in occur times, but sometimes they correspond to very large scale gravitational erosion events. In each group of terrain, downward concave arc erosion process occurs relatively stable, corresponding with small. medium and large scale of gravitational erosion events.(2) Analysis influence of rainfall, rainfall intensity and rainfall duration to gravitational erosion processes, we fund that rainfall intensity have a significant influence to gravitational erosion processes. Each terrain has different characteristic of erosion, rainfall infiltration and runoff process, under different rainfall intensity.When the rainfall intensity small, the large-scale erosion is remarkable. Gravity erosion processes often go with massive erosion event as a beginning rainfall amount does not render a simple proportional relationship with gravity erosion, while have a relationship with both rainfall intensity and rainfall amount.(3) Transform and upgrade the "MX-2010-G" topography meter. The addition of PTZ, convenient removal and vertical verification device, makes the operation more feasible. The instrument can selection of suitable observation position on the condition of guarantee observation angle and laser plane perpendicular.(4) Topography observation has a problem of lens distortion. This study presents a method to rectify the distortion based on ArcGIS. Using the correspondence between the two images, we can correct camera distortion automatically, and then calculate camera distortion errors and complete3D reconstruction as the inside and outside orientation elements are unknown. By experiments demonstrate that the method has good correction effect. Analysis the affection of control points density and lens focal length to correction effect.