Evaluation Research on the Fragility of Geological Environment in China

China's geological environment is fragile fundamentally and has great spatial variance, which greatly affects the socioeconomic development, such as regional allocation of productive force, engineering construction and regional territorial development. Based on the ArcGIS platform, an index system has been developed for the fragility evaluation of regional geological environment, which includes geological structure, earth surface landform and material composition with 9 first level indicators. After carrying out the Min-Max normalization of nine fragility indicators such as the crustal stability, the distribution of fracture zone and elevation, the maps of standard values of all indicators have been obtained in this paper. The correlation among nine fragility indicators has been analyzed by factor correlation analysis. The repetitive elements with significant correlation have been removed based on the principal component analysis, and then a new set of elements on comprehensive fragility has been developed. Taking the mean square deviation contribution rates corresponded to principle component as the weights, the comprehensive index model has been applied to make a comprehensive fragility evaluation of geological environment. Furthermore, with the support of location theory and the GIS spatial statistical analysis, the fragility of China's geological environment has been quantitatively classified into six zones:minor, gentle moderate, moderate, medium, severe, extreme fragile. And then, the spatial characteristics and regional difference about the fragility distribution of China's geological environment have been analyzed comprehensively. The results show that overall fragile is a prominent feature of China's geological environment, and the areas of moderately fragile and extremely fragile zones in China take up appropriately one third of the national terrestrial area. This is also the natural basic condition faced by China's national development and resource exploitation. The overall spatial pattern about the fragile degree of China's regional geological environment shows that the northwest is higher than the southeast, while the southwest is higher than the northeast, besides a little mosaic distribution. Taking the Helan Mountain-Liupan Mountain-Qionglai Mountain-Wumeng Mountain as an approximately boundary, it's found that the fragility of the geological environment in west is high, but the ones in east is low.