基于AHP的天津泥石流灾害评估

Assessment of local debris flow disaster in Tianjin based on AHP method

利用天津市蓟州区降水、地形地貌、人口、地质灾害、DEM数字高程数据等资料,以天津北部蓟州区为研究对象,采用无结构不规则网格设计方法对研究区域进行网格划分,应用层次分析法(AHP)确定直接雨量和间接雨量、水流流速、地形地貌、人口密度、发生频率等泥石流危险因子权重,建立天津泥石流危险度评估模型。利用模型对蓟州区2011-2018年11次强降雨过程进行泥石流危险度评估。结果表明:过程降雨量最大、降雨最为集中的2016年7月20日泥石流危险度最高,雨势平稳的2018年8月12-14日危险度最低;蓟州区2012年7月22日出现的双安泥石流以及2018年7月24日出现的小型山体崩塌,在模型对应的区域内均显示有泥石流风险存在,表明模型对泥石流具有较好的评估能力,可应用于业务和服务中。采用广义极值分布函数计算了蓟州区不同重现期1 h和12 h雨量,利用泥石流危险度评估模型模拟不同重现期雨量的泥石流风险,研究结果可为相关部门和行业提供决策参考。

By utilizing data of precipitation,topography and geomorphology,population,geological disasters and digital elevation mode(DEM),Jizhou district,located in the north of Tianjin,was taken as the research area in this paper to conduct study on assessment of the hazardous degree of debris flow disasters in Tianjin.More specifically,the research area was divided into the grids using the approach of non-structural irregular design,and then the weights of the debris flow risk factors including the direct and indirect amount of rainfall,flow velocity,topography and geomorphology,population density,frequency of occurrence of debris flow were determined,and the debris flow risk degree model(DFRDM)of Tianjin was established based on the analytic hierarchy process method(AHP).This model was used to evaluate the hazardous degree of the debris flow disasters for the eleven strong rainstorm processes over Jizhou district during 2011-2018.The results show that the rainfall process on July 20,2016 with the largest rainfall amount and concentration has the highest risk of debris flow,and the risk for stable rainfall process on August 12-14,2018 is the lowest.Furthermore,the debris flow occurring over"Shuang'an"Village on July 22,2012 and the small landslides on July 24,2018 over Jizhou district,are both captured by the DFRDM model,indicating that this model has a good assessment ability for debris flow and can be applied to real-time operation and service.Moreover,the generalized extreme value distribution function was used to calculate the 1-hour and 12-hour amount of precipitation in different reoccurrence periods of Jizhou district,and the DFRDM was then used to estimate the debris flow risks for different levels of precipitation,which can provide useful reference for the relevant decision-making departments.