Effectiveness of evacuation facilities in Honiara City, Solomon Islands: a spatial perspective

Abstract

Urban areas in South Pacific island countries are experiencing the effects of natural disasters related to extreme weather events, cyclones and flooding. The aim of this study was to evaluate 27 existing evacuation facilities in Honiara City and nearby areas from a spatial perspective. We use the concept of “service areas” to determine whether a given facility, or all facilities taken collectively, is accessible to the populations within its geographic proximity. To determine geographic proximity, we use the network analysis capabilities of a geographic information system (GIS) to establish service areas. Service areas are defined as the area within which people can reach a facility along a road network in a given amount of time based on the cost, or impedance, of travel along the network. Using this approach, we use the overlay capabilities of the GIS to estimate the percentage of each facility’s service area that “captures” the populations, or areas, in greatest need. With GIS census data, road network data, flood hazard data and evacuation facility data from the recent April 2014 extreme weather event, we examine the relative effectiveness of the existing facilities. We focus on disasters associated with severe weather, especially flooding and storm surge. Our analysis suggests that the 27 existing evacuation facilities in Honiara and nearby areas taken collectively provide reasonably good coverage of those populations in greatest need in a flooding or storm-surge event. However, we also find some facilities are poorly located and subsequently under used.