A GENERALIZATION OF THEORY FOR TSUNAMI INUNDATION FLOW RUNNING-UP OVER A SLOPING MOVABLE BED

Abstract

 Aiming for the advancement of tsunami load, historical and/or prospective tsunami scale evaluations, a theory for tsunami inundation flow running up over a uniformly sloping movable bed had been proposed, which was based on a simple tsunami inundation flow model. In the theory, a resistance law (friction factor) for inundation flow over an air-dried sand movable bed was adopted as the resistance law for inundation flow, and it was assumed that the volume of sediment picked up from the movable bed was the same as that of fluid left in the movable bed within the tip region of inundation flow. In this study, at first, a resistance law for inundation flow over an air-dried silt movable bed is examined through conducting new hydraulic experiments, and the resistance law for inundation flow over a movable bed is generalized. Next, the proposed theory for tsunami inundation flow with sediment is also generalized under the condition that 1) the volume of sediment picked up from a movable bed is taken into account and 2) no volume of fluid is left in the movable bed. By using the generalized theory, the run-up, water surface profile in the tip region, bed material movement in the tip region and so on of inundation flow with sediment are discussed, and it is indicated that there are the maximum values of the momentum flux and specific force in each cross section within the tip region of inundation flow (in other words, the maximum wave force) to the density of inundation water.