Xi'an Geological Environment Quality Appraisal Research Based On GIS

Urban geo-environment assessment is one of most important part of urban planning and urban geological disaster prevention and control planning. In this paper, GIS (Geographic Information System) Based Urban Geo-environment assessment is studied at theory and practice level, thinking Xian city as research region.The thesis has analyzed main control factors influencing city region geo-environment synthetically. On the basis of summarizing predecessors' experience, and vector principal component analysis and first rank order method have been adopted to sift and optimize assessment indexes. the thesis has determined geo-environment quality assessment index system and established classifying standard, which aiming at the characteristic of geo-environment quality. According to the characteristic of assessment model, the thesis has adopted mainly expertise to quantify qualitative indexes, while quantitative indexes get their value through fuzzy membership function on the basis of classifying standard. According to the characteristic of urban geo-environment quality assessment, the thesis has chosen two kinds of simple and practical mathematical methods, gray clustering method and fuzzy comprehensive assessment to establish assessment models, hierarchy analytic process has been applied to find the weight of assessment indexes, and then the two assessment results have also been compared. The analysis module is developed with C++Builder6.0 software. Based on the development platform of MAPGIS6.6, the spatial graph database is established. By linking outside database, the property database is performed. Then GIS transfers the property database with interface, so as to achieve link between graph and property, thus forming spatial database. By middle data documents, the integration is accomplished between the assessment analysis module and GIS, thereby achieving transferring data of both sides and carrying on spatial analysis.Based on this system, the geo-environment quality of Xian has been assessed, and the results show that the geo-environment quality can be classified into four classes: best, good, moderate, worst. So, it further indicates that the system is feasible and very practical and that the assessment models are rational.