Spatiotemporal flood risk assessment of underground space considering flood intensity and escape route

Underground space is becoming increasingly vulnerable to inundation owing to the enhanced likelihood and consequences of urban flooding. However, previous studies on flooding of underground space have paid little attention to how rainwater flows inside an underground space, what the optimal escape route might be, how much time would be required to escape, and how dangerous one specific area might be in comparison with another. This study investigated a method for assessing the spatiotemporal risk of flooding of an underground space considering both the flood intensity and the escape route. Two-dimensional hydrodynamic flow analysis was implemented to evaluate the flood intensity. Then, the shortest escape route was determined by applying the Dijkstra algorithm to the nodes and elements used in the 2D flow analysis. In addition, the risk of flooding in the underground space for a case without a water shield was compared with that determined for a case with an installed water shield.