Abstract
An algorithm to search the optimal solution, is proposed for the design problem of countermeasures taken in a floodplain against inundation. The design problem is formulated as to find the land augment pattern which maximizes the evacuation success rate under the constraint of total land level augmentation volume. Two-level random search method is developed to obtain the optimal solution for the problem avoiding impractical computational burden. The method comprises of two levels of searching: one is approximate solution search process based on simple estimation of inundation levels, and the other is strict optimization stage based on the actual simulation of flood inundation. The nested coupling of those two levels of searching has considerably deduced the computational burden caused by the inundation simulation and has enabled us to get practical solution for the design problem.
Using the optimization method proposed in this study, an attempt to estimate quantitatively the relation between facility-based countermeasures and so-called soft-ones for flood disaster mitigation.
