基于GIS的甘肃省甘谷县地质灾害危险性评价

在甘肃省甘谷县地质灾害详细调查的基础上, 通过对研究区地质环境条件及地质灾害基本特征分析研究, 选取了历史地质灾害发育程度、地形地貌、工程地质岩组、地质构造、水文条件、植被条件、降雨量、人类工程活动等影响因素, 建立了相应的地质灾害危险性评价指标体系.采用专家评判方法, 基于GIS技术平台, 对甘谷县地质灾害进行了危险性综合评价, 并与定性评价相结合, 最终将研究区划分为高危险区、中危险区、低危险区、极低危险区4个等级, 其中, 高危险区面积为393.19 km2, 占总面积的25.01%, 中危险区面积为544.04 km2, 占总面积的34.61%, 低危险区面积为324.69 km2, 占总面积的20.65%, 极低危险区面积为310.08 km2, 占总面积的19.73%. 

RISK ASSESSMENT OF GEOHAZARDS BY USING GIS IN GANGU COUNTY, GANSU PROVINCE

Based on detailed investigation of geo-hazards in Gangu County, the authors made evaluation zoning of geo-hazards risk assessment in Gangu County by using the combined qualitative analysis and quantitative evaluation on the GIS platform. On the basis of comprehensive analysis of the present landslides and geological environment in Gangu County, the authors analyzed the main factors controlling the formation of landslides. These factors involve such aspects as ①geo-hazards historical intensity, ② topography and geomorphic, ③ engineering geological layer combination, ④tectonic setting and faults effects, ⑤the degree of vegetation coverage, ⑥the effects of water, ⑦human activities, and ⑧rainfall conditions. With the selected indices quantified according to experts＇ experience, the index system of geo-hazards risk assessment was formulated. The study area was finally divided into 4 levels of the high-grade area, the medium-grade area, low-grade area, and the very low-grade area. According to the results of landslide hazard zonation, the highgrade area covers 393.19 km2 , accounting for 25.01% of the total study area; the medium-grade area is 544.04 km2 , accounting for 34.61% ; the low-grade area is 324.69 km2 , accounting for 20.65% ; and the very low-grade covers 310.08 km^2 , accounting for 19.73% of the whole county.