Quantitative Evalution of geohazards susceptibility based on GIS and information value model for Emeishan City, Sichuan

Exemplified by Emeishan City, Sichuan, 10 factors are selected as the evaluation factors including slope gradient, slope height, slope direction, rock and soil type, geological structure, river erosion, surface cover, rainfall, engineering slope cutting and mineral exploration. On the basis of the grading analysis of the evaluation factors and GIS techniques, the geohazards susceptibility is evaluated for Emeishan City, Sichuan with the aid of the improved information value model. The results of research show that the information value model is scientific and reliable, and the evaluation results are in general agreement with the actual conditions. The geological hazards are best developed in high and steep slopes, hard thin-to thick-bedded sandstones, siltstone intercalated with dolostones, limestone formation and closely spaced structures. Topography, geomorphology and geological structures are believed to be the main factors controlling the geological hazards in this region. The susceptibility of the geological hazards may be classified into four grades:highly, moderately, low and extremely low susceptibility, with the covering areas of 169.37, 429.07, 363.43 and 221.12 km², respectively. The precision of the susceptibility evaluation accounts for 74.80%. It can be seen that the evaluation method presented in this study may serve as a theorectical guide for the susceptibility evaluation of county-scale geological hazards, and the evaluation results may provide scientific data for the prevention and control of the geological hazards in the study area.