Spatial Accessibility of Urban Emergency Shelters Based on Ga2SFCA and Its Improved Method: A Case Study of Kunming, China

Emergency shelters are important public facilities for urban disaster prevention and mitigation. Measuring their spatial accessibility provides a valuable reference for urban modernization and a balanced layout of emergency shelters. In previous studies, the Gaussian two-step floating catchment area (Ga2SFCA) method has the shortcoming of ignoring the effect of a fixed search radius on accessibility. In this study, an improved Ga2SFCA method was proposed to evaluate emergency shelter accessibility in the main urban area of Kunming, China. The parameters of the serviceability of the shelters and the degree of population aggregation were introduced to calculate their effect on the search radius. The traditional Ga2SFCA method and the improved method were compared and analyzed. The results showed that the improved method is more reasonable and realistic in the search radius of densely populated areas and areas lacking shelters, thus providing highly objective and accurate accessibility to emergency shelters. Further, the spatial distribution of the emergency shelters in the main urban area of Kunming was unbalanced and did not match the population density distribution. The accessibility of shelters in parts of the northwestern, eastern, and central parts of the city was low. The method presented in this study could be used to provide reference and support for the government and planners to reasonably plan shelter facilities and promote equal access for all residents to shelter resources.