Research On Geologic Hazards Mechanism And Risk Assessment In Wuzhou Guangxi Based On SDM

With the development of society economy and civilization, geologic hazards have so important effects that human have to provide prevention and cure. As a essential and basic content of natural hazards, geologic hazards risk assessment presents very prominent significance for recognizing, controlling and managing geologic hazards. In the past few years, scholars have launched abundant researches on hazards assessment. However, hazards assessment is a new field which involves wide contents including natural sciences and social sciences so that existing researches are not perfect, and the application level still can not meet demand of reducing hazards. More in-depth studies and further explorations are needed on geologic hazards assessment.Wuzhou is classic mountain city in Guangxi which is at the foot of hill and beside river. Along with city outspreading and project constructing, frequent geologic hazards cause increasing serious threat to people's life and properties. So researches on geologic hazards mechanism and risk assessment by using new scientific approches are developed in the theme, it not only proceeds with a new attempt for enriching geologic hazards therories and approaches, but also has important academic and applied significance for researching geologic hazards in Wuzhou.(1) Through collecting, sorting out basic geographic data, geologic environment background data and geologic hazards topic data in Wuzhou, multiple source character of geologic hazards data is concluded. With the benefit of 3S, integration of geologic hazards multiple source data is realized. Combining with spatial database techonlogy, geologic hazards spatial database is structured. It lays data foundation for next geologic hazards mechanism and risk assessment;(2) On the basis of geologic hazards spatial database, by drawing support from geo-infomatic atlas, using GIS spatial statistical analysis, overlaying analysis, buffer analysis and DEM modelling, geologic hazards time and space distribution is closely analyzed, geologic hazards growth feature and formation conditons are concluded. Based on geo-informatic atlas and GIS, geologic hazards distribution rules and mechanism analyses are implemented. It provides sceientific reference frame for next constructing assessment indicator systems;(3) Through analysing SDM theories and means, discussing some general SDM means in geologic hazards assessment such as information content model, fuzzy comprehensive assessment and neural network, rough sets and geo-rough space are put forward to assess geologic hazards. In accordance with geo-informatic atlas analysis results of hazards mechanism, geologic hazard danger and element vulnerability assessment indicator systems are established;(4) Hazard and vulnerability assessment knowledge representation system and decision table are built up based on rough sets and geo-rough space. At the same time, concrete algorithms to accomplish model are constructured, so assessment indicator system is optimized and their weights are confirmed. Combining with fuzzy comprehensive assessment, indicator weighs and their value in decision table, gradations of hazard and vlunerability are divided. Moreover, by comparing with information content model and field surveying, the assessment results above-mentioned are certified as correct;(5) Based on assessment results of hazard and vulnerability, geologic hazards risk assessment is accomplished, it is divided into four gradations such as high risk, middle risk, low risk and very low risk, every gradation is also divided into several subtypes. With the aid of GIS, assessment results are visualized;(6) Problems on geologic hazards prevention and cure in Wuzhou are systematically generalized, and moreover, some countermeasures and proposals are gived.