IMPROVEMENT OF TSUNAMI-INDUCED SEDIMENT TRANSPORT MODEL BY CONSIDERING SATURATED CONCENTRATION IN SUSPENSION WITH STRONG UNSTEADY FLOWS

Abstract

 In this study, factors causing the underestimation of morphological changes due to tsunami-induced sediment transport in Kesennuma Bay with narrows during the Great East Japan Earthquake and Tsunami have been numerically investigaed. Based on the estimation, the saturated concentration of suspention model was improved. It was found out that strong unsdeady flows occerred at narrows. The numerical results from conventional saturated concentration model implied that at the narrows, suspension concentration and sediment supply from the bottom to the suspension were limited by high concentration in suspension, leading to underestimation of morphological change, i.e., erosion and deposition. By considering effects of strong unsteady flows on concentration of suspention, a new form of saturated concentration model based on log-wake law and Kármán constant theory has been proposed. Numerical results of the erosion and deposition in Kesennuma Bay were improved. It is expected that accuracy of evaluation about not only morphological changes but also inundation area and damages are improved.