Estimating Evacuation Distance, Time, and Range to Shelters Through Network Analysis

This study employed the QGIS spatial information analysis tool to conduct network analyses through the O-D Matrix and ISO-Area methods. These network analyses calculated travel distances and evacuation times from flooded residential buildings (evacuation start points) to shelters (evacuation end points) in the event of a reservoir collapse. Feasibility of evacuation from each residential building was assessed by comparing the evacuation time with the initial flood wave arrival and peak flood level occurrence times. Walking speeds were set based on population characteristics: 1 m/s for children and the elderly and 2 m/s for adults (fast walking). Using a walking speed of 1 m/s, evacuation zones were established at 300-meter intervals, representing a 5-minute walking distance for each shelter. The resident population per building was estimated to determine the number of evacuees, and shelter capacity was calculated based on the required space per person.