Evacuation under flooded conditions: Experimental investigation of the influence of water depth on walking behaviors

Abstract

Flooding can be considered as the most frequent type of natural disaster, and it is an unavoidable phenomenon in many parts of the world. Ensuring the safety of people during such natural disasters is extremely important. To propose guidelines for evacuation planning during floods and to develop simulation tools, which can be used in evacuation planning, empirical data are needed under different flooding conditions. However, there is a lack of data and studies on such aspects. This study examines the influence of water depth on human walking behaviors under hydrostatic conditions using the data collected through a controlled laboratory experiment. Three floodwater levels, i.e., 0.08 m, 0.43 m, and 0.90 m were considered to represent ankle, knee, and waist heights, respectively. Results explained that the walking speeds monotonically decrease with increasing water depths. Further, for the 0.90 m water level, the mean walking speed of males was significantly higher compared to the mean walking speed of females. Characteristics of individual walking trajectories were also investigated, and it was identified that the average step frequency for walking in water was significantly lower than that for walking under normal, i.e., without water, conditions. However, the average amplitude of the lateral movements for walking in water was significantly higher than that for normal walking. The speed profiles and trajectory data corresponding to different water depths could be useful as basic data for vital applications, such as developing and calibrating simulation tools, which could assist in decision making in evacuation planning.