基于斜坡单元的陕西省城镇地质灾害风险调查评价——以西安市蒋村街道为例

Investigation and Evaluation of Urban Geo-hazards Risk in Shaanxi Province Based on Slope Unit——A Case Study of Jiangcun Street in Xi’an

以陕西省西安市蒋村街道为研究区,在地质灾害隐患早期识别和详细调查的基础上,总结分析了研究区地质灾害的分布特征和形成条件;基于高精度DEM数据,对研究区具备孕灾条件的区域划分了斜坡单元并逐坡开展了大比例尺(1∶10000~1∶2000)调查,查清了孕灾地质环境条件和危险区范围内的承灾体,通过统计分析确定了研究区地质灾害发育的主要影响因子,利用层次分析法确定各因子权重,采用综合指数法实现了所有斜坡单元的地质灾害易发性评价,并以不同频率(10%、5%、2%、1%)下的年最大日降雨量作为灾害触发因素,进行了基于极值降雨假设的地质灾害危险性评价,在此基础上采用定性评价和模型方法分别进行了地质灾害的易损性和风险评价,确定了研究区内每一个斜坡的风险等级。通过典型区域实地核查,验证了评价结果的可靠性,并与研究区以往调查评价结果进行了对比分析。

Taking Jiangcun Street,Xi’an City,Shaanxi Province as the study area,based on the early identification and detailed investigation of geo-hazards,we summarize and analyze the distribution characteristics and formation conditions of geo-hazards in the study area;Based on the high-precision DEM data,the slope units are divided for the areas with disaster pregnant conditions in the study area,and a large-scale(1∶10000~1∶2000)survey is carried out slope by slope to find out the disaster pregnant geological environmental conditions and the disaster bearing body within the dangerous area.The main influencing factors of geological disaster development in the study area are determined through statistical analysis,and the weight of each factor is determined by analytic hierarchy process,The comprehensive index method is used to evaluate the geological disaster susceptibility of all slope units,and the annual maximum daily rainfall at different frequencies(10%,5%,2%,1%)is used as the disaster trigger factor to evaluate the geological disaster risk based on the extreme rainfall hypothesis.On this basis,the vulnerability and risk of geological disasters are evaluated by qualitative evaluation and model method,The risk level of each slope in the study area is determined.The reliability of the evaluation results is verified by field verification in typical areas,and the results are compared with the previous investigation and evaluation results in the study area.