Landslide susceptibility assessment based on GIS and weighted information value: A case study of Wanzhou district, Three Gorges Reservoir

The susceptibility evaluation was conducted at Wanzhou district where landslide hazard largely occurred in the reservoir region of Three Gorges. Based on the results of the graded state of index factor and the correlation analysis, seven influence factors were chosen to be the evaluation indices including the gradient, the direction and the structure of slope, the stratum lithology, the geological structure, the role of water, and the land use. The frequency curve of landslide and the magnitude curve of information were drawn according to over 700 sample data of landslides. Catastrophe points on the curve were chosen as the critical value to determine the factor states on dividing the entire factors interval, so that to establish the system of susceptibility evaluation. Based on the grid data model of GIS and the method of weighted information value, the susceptibility evaluation was developed. The results show that the high and relatively high susceptibility areas are mainly the construction land, J2s2 and J2s3 stratum, area of reservoir water fluctuation, river net influenced area and urban area of Wanzhou city. The statistical results indicate that the areas with high and relatively high susceptibility taking up 1210 km2 in total are about 9.71% and 25.9% of the entire area under study respectively. The accuracy of the assessment is about 87%. This paper describes the theoretical methods and technical route of landslide hazards susceptibility evaluation in the district. The research provides a technical support for the regional landslide disaster prevention and forecasting and provides a theoretical guidance and technical reference for the nationwide county landslide hazards evaluation.