The main purpose of this study is to estimate the risk of inundation caused in storm surge, high wave and tsunami a highly-developed compound coastal urban area. The risk of inundation is cataloged according to the social importance and population in the target areas.
　An experiment on compound coastal urban area model representing the ground and underground facilities was conducted to evaluate the risk of inundation. Tsunami is employed as a model disasters which may cause heavy inundation in the coastal area. The severest tsunami in Tokyo bay due to an earthquake like Kanto earthquake in 1923 was presumed in the risk assessment and it is implemented as an input condition of the experiment.
　The behavior of inundated water in the complex geographical features was examined. Especially the depth of inundation and velocity of flood in underground space were observed. The high risk of the inundation in the underground space was demonstrated from the results of the experiment in the compound coastal urban area model. The velocity of flood at the entrance of underground area became terribly large and exceeded the acceptable limit for people to escape.