REGIONAL LANDSLIDE HAZARD ASSESSMENT AND RISK MANAGEMENT

With the development of society and economy, human beings keep on expanding their living space to mountain areas. As a result, geohazards such as landslides occur more and more frequently in recent years. The importance of landslide hazard prevention and mitigation has been gradually taken into great consideration more than ever, therefore it is urgent to find out a realistic solution to control and manage landslide hazards. Furthermore, regional landslide hazard assessment and risk management are built upon regional landslide hazard assessment A reasonable discussion has been dug into this research area, and major creative outcome has been obtained as follows. (1) An integrated methodology system of regional landslide hazard assessment has been established, and the fundamental framework of regional landslide risk assessment and risk management has also been refined. The objective, task, content and implementing process of regional landslide risk assessment and risk management have been illustrated systematically. Then an applicable workflow has been put forward for regional landslide risk assessment and risk management as following, objective confirmation of assessment and management→historical information collection and analysis→field investigation and monitoring of landslide hazard→database establishment for regional landslide hazards→regional landslide hazard assessment→regional landslide hazard management (2)The regional landslide hazard has been put forward as a formal conception, and the common and difference between regional landslide hazards and the other kinds of hazards have been clarified. It is pointed out that both the single hazard pot and regional hazard should be taken into consideration with the same importance when carrying out regional landslide hazard assessment and risk management The results of regional landslide hazard assessment and risk management could only be a gross generalization. (3) The principles and methods of regional landslide hazard assessment have been discussed systematically. The emphasized points are as follow. During the process of the hazard assessment, the objective should be subdivided into several sub-objectives based on geologicalprocess—mechanism analysis, and the hazard of each sub-objective should be assessed with corresponding appropriate factors respectively; To improve the accuracy of the assessment results, it is necessary to determine the actual scope and mode of how factor impacts the developing and occurrence of landslide hazard, and to research its spatial characterization of influence and impact intensity in this scope as wells Qualitative analysis should be taken as a necessary supplement to quantitative math models; Landslide hazard assessment result will not only elaborate the degree of hazard, but also clarify the key factors to induce the hazard. (4) A realistic solution for the regional landslide hazard assessment has been provided as following procedure: analyze formation mechanism→subdivide region→analyze with mathematic model→generally assess. At the same time, this procedure has been totally integrated into GHGIS, a system built upon MAPGIS platform to assess and forecast regional landslide hazard. (5) The fundamental framework of regional landslide risk assessment and risk management has been fulfilled It has been predicted that using risk assessment proactively will be at least beneficial with us geological researchers, for it will push us to pay more attention on how to express the inherent uncertainty of landslide hazard more widely. Regional landslide risk assessment is based on the regional landslide hazard assessment, but cannot replace regional landslide hazard assessment entirely. (6) The process of how to implement each composition of framework and the necessary geological consideration that should be taken into when implementing the process have been elaborated systematically. A method of using probability to express hazard degree has been put out creatively; It is supposed to simply perform gross loss estimate according to actual situation when analyzing regional landslide vulnerability; It is pointed out that regional landslide risk assessment is better based on qualitative assessment; The decision on risk acceptance level and risk control solution selection are not only concerned with the gaming between cost and income, but with the deep geological analysis and recognition. (7) A new methodology, comprehensively rated factors multiplication method(CRFMM), which combines quantitative method with qualitative method has been proposed, and has been fully applied into Gongxian County in Sichuan Province. Based on analyzing of developing and, distribution characterization, the hazards in Gongxian County were divided into these six categories: karst collapse-fissure, landslide triggered by mining, avalanche triggered by mining, collapse triggered by mining, nature landslide, and nature avalanche. The results of hazard assessment made with CRFMM are accordance with actual situation. Moreover, the results are easier to understand than the results obtained by using traditional mathematical models. Hazard vulnerability is also sketched out in the county, and then regional risk assessment is performed on all kinds of hazards as well. The case study shows that research thinking and methodology will be useful to push forward the development of regional hazard assessment and risk management.