A Case Study Of Geological Hazards Risk Assessement In A Large Scale Mountainous Environment

The war between humans and geological hazards has nenvr interrupted during the long history of the human beings. Nowadays within the abnormal weather condition,the plate movement is activity, and we humans continued expanding our living space, geological hazards, the damage which it made is only a little bit lighter than the earthquake, has become the second serious nature hazards. Geological hazards has a characteristics of emergency, multiple and continuous, in order to enhance the ability of disasters prevention and reduction, it is very necessary to know the development characteristic and to learn the development rule of the geological hazards, foremore, to estimate what kinds of damage would be done by the hazards, that is what's the risk assessement theories concerned. The geological hazards risk assessment has been studied for many years, though there are different opinions about the research mathods and technical systems, risk assessment is deemed as an importmant step for the hazards prevention and reduction by the scholars all over the world. And also it is been seen as the precondition and the basement of the risk management and make planning for the region.If the risk assessment result is reasonable enough or it could be used to guild the hazards prevention and reduction mainly decisioned by three factors. The first is to build an overall and systemic assessment index system that the characteristics of local geological hazards could be embadyed in it; The second is to build a precise assessment model; The third is to integrate the index and the model into a platform such as GIS in order to take rapid analysis and make correct decision. The paper focuses on the key issues about risk assessment, standing on the lastest research development both domestic and abroad, takes Garze, which has a sensitive geological environment, a number of geological disastersas and a backward social and economic condition region in the mountain area in western China as the instance, takes the Geological Hazards Assessment Methodology as a guide, directed towards the two core issues of the risk assessment– the probability and loss, respectively quantified by geological hazard assessment and vulnerability assessment, constructing a risk assessment model to quantitative risk and classification the risk. Throughout the process inegrate the expert knowledge and experience into the risk assessment theory and the methods, special focus on the application of remote sensing technology in risk identification and information extraction, information technology in spatial analysis and data management, the main results obtained is as follows:(1) More comprehensive methodology for risk assessment of geological hazards are discussed. Disaster risk assessment methodology, including the study of geological terms the basic concepts involved in Detailed; risk assessment and statistical probability distribution commonly used description of the method and the basic content of the discussion of risk assessment.(2) Initially established a platform based on GIS technology of geological disaster risk assessment system. The complexity of geological data management, retrieval and analysis makes the inevitable the use of GIS in the disaster risk assessment. The paper discusses the geological hazards risk assessment based on GIS could follow the way"Build database→Analysis→Redevelopment→Application". The underlying database includes regional geological environment data, volume data disasters, socio-economic data and real-time monitoring data, etc. Analysis can be overlay analysis and statistical analysis of neighborhood, etc. Demand-driven development process can be carried out based on different platforms to facilitate disaster management, and data updates.(3) Choosing 11 cactors that are considered as have an important"contribution rate"of the disaster development according to disaster-causing mechanism and construction the assessment index system. Using information value model which is very suitable for a large scale to assess the geological hazards risk. By risk identification and hazards analysis, initially understand the quantify, tpyes, distribution and development features of Garze geological hazards. Find out the susceptibility degree of hazards and based on that calssify the hazard into four degree.(4) Try to assess the geological hazards vulnerability under an incomplete data condition. The difficulty of vulnerability assessment lies in the difficult to obtain the evaluation data. First, because there are too many elements at risk to statistics, and second some elements at risk cannot be quantified of their values. For this problem, a method of combining qualitative evaluation and quantitative evaluation is used in this paper, using relativity and available data to instead of unacquirable, using of qualitative methods if the data cannot be quantified of their values.(5) The risk assessment and divisional evaluation of Garze geological hazards. Based on the current risk assessment model, taking the capability of disaster prevention as a factor of the involved in the evaluation, building Ganzi Geological Hazards Assessment Model. The results indicated the geological hazards has a feature that lower in the north and west and higher in the south and east of Garze. The highest risk source located in the high-mountain gorge areas in the east and east-south where there have a feature that prone to hazards, densely populated, a better social and economic conditions, while the high plain and hilly Plateau in the west and west-north are suggested to be the low risk area.(6) By "investment - benefit" analysis and classification management principle, taking the "governance, monitoring, removal" as the geological hazards risk management scheme. The hazards that have a high level of risk and threat of impartment equipment and people are suggested to engineering treatment to eliminate the risk;"mass observation and mass preparedness"system should be constructed in the middle risk area and professional monitoring measures should be took into practice in high risk area; peoples who located in the high risk area and the hazards are difficult to control are suggest to move in order to avoid the risk.