Urban Flood Inundation And Risk Mapping Using GIS And Multicriteria Decision Analysis

In recent years,flood caused by heavy rains occurred frequently.In addition to coastal cities,the possibility of disasters risks in inland cities(such as Wuhan,Zhengzhou,Xi'an,etc.)is increasing.Wuhan is located along the Yangtze River,the summer sudden precipitation events are concentrated.And the Yangtze River flood season is also in the summer.During this period,the water level of Yangtze River increases,and the difficulty of urban drainage increased.Combined with the impact of global warming,the city's waterlogging caused a widespread concern at home and abroad.Based on GIS technology and multi-criteria decision analysis,this paper presents the idea of using AHP and GIS to evaluate the risk of urban flood,and draws the risk map in Wuhan city center.The concept of fuzzy mathematics is introduced,and the fluctuation range of each factor is determined by fuzzy AHP.Based on the Latin hypercube sampling method,the mean absolute rate of change(MACR)of the pixel evaluation results was used to quantitatively evaluate the influence of the fluctuation of the participating factors on the risk evaluation results.At the same time,the sensitivity of the participating factors was analyzed by OAT sensitivity analysis method,and the sensitivity of these factors was analyzed.(1)Summarized the main driving factors of urban storm waterlogging disaster,and analyzed the similarities and differences between the driving factors of coastal cities and inland cities,presented the main influencing factors of rainstorm water in Wuhan.(2)Constructed the urban rainstorm hazard assessment index system.Based on the relevant research experience at home and abroad,considering the unique geographical and hydrological environment and social development factors of Wuhan City,five evaluation factors such as elevation,slope,land use,distance from lake and rivers and distance from surface runoff network were selected.(3)Using analytic hierarchy process,calculating the weight of each factor and the classification of various factors.The questionnaire is designed and the decision matrix was obtained synthetically.The weight of each evaluation factor and the factor assignment are calculated by the decision matrix,and the consistency test was carried out.The maximum weight of land use is 0.4128,and the weight of the distance from the rivers and lakes is 0.0666.(4)Evaluation of the risk of urban storm waterlogging,and drew the grading map of urban waterlogging hazard in Wuhan.Using the spatial analysis function of GIS technology,the weighted superposition method was used to calculate the risk score of urban storm waterlogging,and the scores of each pixel were evaluated and analyzed.The risk classification of rainstorm water in Wuhan was drawn.(5)Weight-based sensitivity analysis.The fuzzy mathematics theory is introduced to determine the fluctuation-range of the weight of the participating factors,and the sensitivity analysis of the weights is carried out by using the Latin hypercube sampling method and the OAT sensitivity analysis method.Among them,the sensitivity of land use type factor is the strongest,and the sensitivity of lake distance factor is the weakest.