The Terrain Factor In The Sichuan Landslide Hazard Evaluation Of Sensitivity To The Applicability Of Analysis

Landslide is a severe disaster, moreover the loss caused by it has been greater and greater recently. There are numerous factors that will impact on the development of landslides. Most of these factors are interacting, and their contribution to the landslides has a great variability. In order to accurately evaluate the sensitivity of landslide hazard, it's necessary to select the key factors that participate in the sensitivity evaluation by analyzing the relationship between the factors in detail. Topography is the main factor to control the spatial distribution of landslide hazard, so it's of great significance to discuss the applicability of terrain factors in the sensitivity evaluation of landslide hazard.Digital elevation model contains a large amount of topographic information, it's the basic data that quantitatively descripes spatial variability such as the landscape structure, hydrological processes and bio-distribution; besides it's the main datasource to obtain topographic information. With the rapid development of GIS technology, more and more scholars choose the DEM as the information source, and based on which extract terrain factors to do some terrain analysis. The paper takes SiChuan Province as the study area, where landslide hazard is very severe and extracts eight topographic factors such as slope based on the widely-used SRTM DEM data by presenting the principles of the extraction in detail, then discusses the applicability of these factors in the landslide hazard sensitivity analysis on base of quantitatively analyzing them. At last, the co-relationship between the classes of selected factors and the landslide hazard is analyzed to discuss the terrain influence on landslide hazard further. Details are as follows:1. By analyzing the distribution characteristic of landslide hazard in the study area, the author points out the workflow of the paper is data acquisition, data processing, selection standard of sensitivity assessment, analysis of sensitivity assessing model to applicability determining.2. Discussing the terrain data acquisition and the terrain information analysis, based on which to select the terrain factors, they are slope, aspect, profile curvature, plan curvature, the relief amplitude, the earth's surface incision, surface roughness and the Variance Coefficient in Elevation.3. Discuss the influence of DEM grid size on the precision of terrain factors extraction. By statisticing the data, the author finds out that the bigger the grid size, the lower the precision of terrain factors is, which reflects the low precision DEM simplifies the terrain relief.4. Mean change point analysis method is used to determine the best statistical unit of the terrain factors, then the macro-terrain factors extraction of the study area is completed, and the factors are classified according to some certain standards. The best statistical units of the relief amplitude, the earth's surface incision and the variance coefficient in elevation are as follows: 1km2,1.21km2, 1km2, which are determined by calculating.5. The paper analyzes the connection between terrain factors and landslide hazard by way of the sensitivity analysis model and the uncertainty factor(CF)method. The variance coefficient in elevation, profile curvature, surface roughness, the earth's surface incision and slope are the factors calculating by the sensitivity analysis model to evaluate the landslide hazard; The results of CF method are the variance coefficient in elevation, profile curvature, surface roughness, the earth's surface incision. On account of the little differences between the two methods, the paper takes the logistic regression model to verify the result, in order to determine the final applicability of all terrain factors in the landslide hazard sensitivity evaluation. The factors determined last are the variance coefficient in elevation, surface roughness, the earth's surface incision and slope.