Abstract
This paper discusses a basic concept of scenario-based real time prediction of storm surge disasters. A scenario of storm surge disaster is made which illustrates the actual disaster occurred in Suo-nada Bay, Japan by typhoon 9918. If enough number of scenarios of disasters can be made before the typhoon for all the possible cases of storm surges and waves, the disaster can be predicted. The real time prediction is closely related with the performance design of coastal defenses.