Using the variable two-step floating catchment area method to measure the potential spatial accessibility of urban emergency shelters

Abstract

As a public service facility that provides relief, resettlement, and evacuation services to disaster-affected people, emergency shelters play a vital role in helping people cope with disaster events. The measurement of spatial accessibility of existing emergency shelters is a key task in improving emergency shelter services and minimizing property losses and deaths. In this study, considering the differences in emergency shelters’ service capacities and population distribution, we developed a two-step floating catchment area (2SFCA) method with a variable service radius and evacuation radius to describe emergency shelter accessibility in Lanzhou’s core area and compared with the traditional 2SFCA method. Furthermore, we used bivariate local Moran's I to identify the spatial relationships between emergency shelter accessibility and population density. The results show that the traditional 2SFCA method underestimates accessibility in densely populated areas with dispersed emergency shelters. Shelter accessibility in Lanzhou’s core area is unevenly distributed, with the lowest levels of accessibility in densely populated areas. There is an obvious spatial mismatch between the accessibility of emergency shelters and the population density, and the central and western part of Chengguan has a serious shortage of emergency shelters. This study provides important information for the planning and construction of emergency shelters.