Carrying capacity evaluation of Beijing emergency shelters based on AHP-EWM multi-objective decision modeling
Emergency shelters can be used for sheltering,rescue,and evacuation of residents after a disaster.These structures are an important part of national public security and emergency management.Evaluating the carrying capacity of emergency shelters is important in promoting the construction of resilient cities and the sustainable development of cities.Beijing is one of only three capital cities in the world that are located in a zone of VⅢ degree of intensity.It is also the earliest city in China to build emergency shelters,and thus,it is typical and representative in terms of emergency evacuation.In this study,we use remote sensing images,POI,and other multi-source data to construct an evaluation model of the carrying capacity of urban emergency shelters based on multi-objective decision making,and take the Fifth Ring Area of Beijing,where the population distribution is relatively concentrated,as an example.First,according to the principle of establishing evaluation indexes,evaluation indexes are selected from four aspects:safety,accessibility,effectiveness and security,and relevant experts in disaster evaluation are invited to screen out 14 indexes according to their importance and relevance,constituting a system of evaluation indexes for the carrying capacity of emergency shelters.Second,subjective and objective weighting methods are used to determine the weights to make up for the lack of single weights.Subjective assignment adopts Analytic Hierarchy Process(AHP),and objective assignment adopts Entropy Weighting Method(EWM).Commonly used weight combination is the average of subjective and objective weights,while this study adopts maximum sum of squares of deviations theory to solve the optimal weight coefficients of the combination of assignments.Then,based on the multi-objective decision-making model,a 30 mx30 m grid was used as the evaluation unit,and a multi-objective linear weighting method was used to calculate the evaluation scores of the carrying capacity of the emergency shelter.And the natural discontinuity method was used to grade the carrying capacity.Finally,considering the complexity of the disaster after the occurrence of the disaster,including the degree of damage to the building and the potential secondary disaster impact,and referring to the relevant norms and standards,the evacuation scenarios are categorized into short-term evacuation and medium-and long-term evacuation scenarios according to the number of evacuees.The carrying capacity of different evacuation scenarios is simulated and analyzed using the method of this paper.Results show that the carrying capacity of the Fifth Ring Area of Beijing is good,but the carrying capacity of the second and third rings is zero,and an imbalance exists between the rings.This study provides qualitative and quantitative basis for the evaluation of the carrying capacity of urban emergency shelters.It also provides decision support for the planning and layout of emergency shelters and the efficient allocation of resources.
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