Evaluating the Crowdedness of Urban Emergency Shelters Based on the Improved Gravity Model

Abstract

Abstract The evaluation of the crowdedness of urban emergency shelters is highly important for the evacuation and advance planning of emergency shelters. Given the urgency of evacuation following a disaster, this study assesses the buildings in a residential area, and attempts to improve the existing gravity model of emergency shelter evaluation through the introduction of population-scale influence factor, emergency shelter service capacity and travel limit distance. The study considers parts of the Chengguan District of Lanzhou City as an example. Based on the attraction of emergency shelters to the residential area, the residents are allocated to each emergency shelter for quantitative analysis of urban emergency shelter crowdedness under different travel limits distances. The results show that the crowdedness differs greatly depending on the distance to the shelter, and becomes worse due to the small number of emergency shelters in the Southwest region. With the increase of the travel limit distance, the number of emergency shelters that can be reached by the residents increases; consequently, the crowdedness decreases, which shows a trend of increasing from northeast to southwest. The improved gravity model considers the travel distance, population size and service capacity of emergency shelter. The model allows us to evaluate the impact of the travel distance on the crowdedness of emergency shelters when the travel distance is short, and assess the service capacity of emergency shelters when the travel distance is long. The use of this model can reasonably and reliably reflect the crowdedness of emergency shelters and provide a scientific basis for the planning and decision-making of relevant government departments.