Abstract
In this study, we built a risk assessment approach for whole basin that treats the dike break as a probability event and takes into the relationship between upstream and downstream. In addition, we proposed the strategic decision-making approach for dike construction to minimize the flood risk of whole basin by using the risk assessment approach and confirmed its behavior by applying to assumed flood plain. As a result, we showed that the strategic decision-making of constructing the dike of low height in the upstream maximizes the social benefit depending on the conditions such as the land use in basin. In the future, we will refine the calculation method of the probability of dike break and the flood damage cost in order to apply this proposed strategic decision-making approach to the real river basin.
