Risk Assessment On Mountain Torrent Disaster In Small Watershed

Mountain torrent disaster is one of serious natural disasters in China. Mountain torrent disasters caused serious economic losses and casualties in all kinds of natural disasters, restricting economic and social sustainable development of mountain district. The uncertainty of flash flood risk analysis can be an objective description so that the flash flood risk assessment is gradually become a hot spot. This research mainly utilize GIS technology, combining with the hierarchical analysis method, by collecting related information of the southwest mountain torrent disaster typical area Ludian county.Extracting the typical small watershed and establishing of mountain torrent disaster risk evaluation model, it can be concluded from three aspects:mountain torrent disaster risk vulnerability and risk evaluation:(1)Typical area mountain torrent disaster risk theory:mountain torrent disaster risk theory of small watershed is composed of mountain torrent disaster risk and vulnerability, combined with the regional survey, measurement and field visits,considering risk zoning in typical area.(2)Evaluation of the hazard in the area of mountain disasters:Hazard assessment subsquently study area is mainly from two aspects of the environment and to evaluate.Using GIS spatial analysis methods, including the geological conditions of slope and the ups and downs Average annual rainfall Subsquently environment, such as vegetation coverage and human activity factor index system.By collecting data,combined with local actual situation carries on the quantitative evaluation indexes for classifying and assignment.Contribution degree of various indicators of subsquently environment with weight value, using analytic hierarchy process(AHP) to expert scoring weight value.The annual rainfall and flood frequency in the study area were collected for quantitative assignment,eventually it could be gotten pregnant disaster environment and the index of hazard-formative factors as a result, the use of GIS space superposition function, realizing the hazard assessment in the study area.Ultimately it is divided four high level of danger middle level of danger, dangerzone and low in the danger zone.(3)Mountain torrent disaster vulnerability assessment research: in the study area of vulnerability evaluation mainly from two aspects carries on the analysis and evaluation.In line with the premise of people-oriented, from the study population vulnerability and economic vulnerability.This study selected in the southwest mountainous area of underdeveloped area, considering the characteristics of hazard-affected bodies properties, main selection population and cultivated land were analyzed.Finally vulnerability of the study area are divided into four levels: high vulnerability,middle vulnerability, vulnerability and low vulnerability.(4)Flash Flood Risk Study in research area: on the base of risk and vulnerability,through the assignment of different levels, using formulas Risk(R) = Hazard(H) x Vulnerability(V), the study area is divided into three levels: high risk, medium risk,low risk and micro risk.(5)According to the result of risk area division, scientific and feasible prevention strategies and measures are put forward, and mountain flood process of unsurveyed area were discussed.