Accuracy improvement of movable bed model for tsunamis by applying for Kesennuma bay when the 2011 Tohoku tsunami arrived

Abstract

As a model to estimate sediment transport and topography change by tsunamis, Takahashi et al. (1999) proposed a movable bed model theoretically and experimentally. In this paper, the model was applied to Kesennuma bay when the 2011 Tohoku Tsunami arrived. It was able to simulate erosion around the narrow area and deposition in the inner part of the bay, however, whole profile was not enough reproduced and deformation volume was underestimated. To improve an accuracy of the model, parameter study was carried out and three dominant factors were found. They are non-dimensional shear stress, coefficients of sediment transport equations, and saturated suspended sand concentration. A model improving the factors is proposed and the model was made remarkable progress for the sediment transport distribution from the entrance to the narrow area of Kesennuma bay.