Exploring pedestrian movement characteristics during urban flooding: A micro-simulation approach

Urban flooding events have emerged as increasingly prevalent and severe natural hazards, owing to the influence of climate change and human-induced activities. However, pedestrian locomotion in floodwater diverges significantly from level ambulation due to the complex interaction between pedestrians and water. To systematically investigate this mechanism of interaction, we propose the integration of a drag force into the social force model to simulate pedestrian movement behavior under floodwater conditions. The modified social force model was conducted for sensitivity parameters analysis and calibrated by three controllable experiments. Based on this calibrated model, an in-depth investigation has been conducted to analyze the influence of water depth and water flow velocity on pedestrians’ movement speed. Simulation results suggest that as water depth gradually incrementally rises, the drop rate of speed in running conditions is notably faster than that of walking conditions no matter what water flow speed and direction was. In addition, we propose a mathematical model capable of predicting pedestrians’ movement speed under floodwater conditions. These findings will offer valuable insights into the risk assessment of pedestrian evacuation in flooding scenarios.