基于GIS和AHP的芦山地震灾区泥石流危险性评价

采用层次分析法，通过判断矩阵建立起各要素之间的数量关系，选取坡度、地层岩性、断裂带、植被覆盖、地震烈度及年降雨量作为评价指标，并阐明了各指标与泥石流之间的相互关系。建立以地理信息系统为平台的泥石流危险性评价模型，得到地震灾区泥石流危险等级分区图。通过评价，初步认识到研究区内芦山县、天全县、名山区、雨城区位于泥石流极高危险区，且评价分区结果与区内地灾点分布特征相吻合

HAZARD ASSESSMENT OF DEBRIS FLOW BASED ON GIS AND AHP IN LUSHAN EARTHQUAKE DISASTER AREA

A seven magnitude earthquake occurred in Lushan County, Yaan City, Sichuan Province on April 20, 2013, which caused 193 deaths or missing and with a loss amounting to RMB 1.4 billion. The structure of mountains, rock and soil was severely damaged by the Lushan earthquake, which induced a series of geological disasters including landslide, collapse, debris flow and so on. The serious geological disasters threatened the life, the property of the local people, the significant infrastructure and even the ecological condition. Exhaustive study and hazard assessment of debris flow in Lushan earthquake were of important realistic significance. Using the AHP method, we selected six assessment factors, namely terrain slope, lithology, fracture zone, vegetation cover, earthquake intensity and annual rainfall. In the application of AHP method, the weight of each factor was determined. The weight is 0.186 for seismic intensity, is 0.284 for rainfall factor, 0.176 for slope, 0.169 for lithology, 0.108 for fracture zone, and 0.077 for vegetation cover. The study area was eventually classified into five categories (extremely low, low, moderate, high, extremely high), which were determined according to the views of experts as well as the understanding of the regional development of geological hazards. Grade 1 to 5 were used to indicate the different hazard levels. Grade 5 represented the most dangerous, while Grade 1 represented the least dangerous. The choice of GIS technology for spatial analysis completed the study using the weighted superposition model. Applying the spatial analysis tool in GIS, a zoning map of debris flow hazard assessment was obtained. The result showed a regular pattern that the study area such as Lushan County, Tianquan County, Mingshan District, and Yucheng District located in the extremely high hazard area, and its level of hazard zoning was mainly affected by the earthquake and rainfall factors. We draws a conclusion that the division of the study area and the feature of geological hazard point distribution were in substantial agreement.