Science of Tsunami Hazards (May 2019)
THE BEHAVIOR OF A TSUNAMI-LIKE WAVE PRODUCED BY DAM BREAK AND ITS RUN-UP ON 1:20 SLOPE
Abstract
A solitary wave is commonly used in tsunami study for both physical and numerical models. A tsunami is categorized as a long wave which drastically changes its shape and speed when propagates in shallow water and land. In this paper, a physical model test of tsunami propagation based on Dam Break system to produce a tsunami-like wave was carried out. In a flume, finite reservoir length is set to sufficiently provide downstream length for propagation and run-up area. The downstream part is divided into two sections of bed configuration where it has flatbed as shallow water region and 1:20 of sloping beach model. The effect of the ratio of the reservoir depth to the initial downstream depth ( ) is discussed. In addition, the tsunami inundation depth and run-up in land were also investigated. For comparison of results, numerical model similar to the physical one was conducted. The numerical model was based on a set of nonlinear shallow water equation that employed second-order explicit leap-frog finite difference scheme. The use of numerical approach using shallow water equation may not yield realistic results since the wave evolution in shallow water and coastal area has not sufficiently accommodated. The comparison between the models suggested that the numerical model consistently produce slightly higher run-up than its counterpart. This was probably due to the application of shallow water equation (SWE) in the numerical model which could not entirely solve vertical convection problems, breaking waves, and turbulence-related aspects that reduced run-ups energy. A finetuning method to improve the numerical model run-ups is necessary by introducing proper artificial energy reduction mechanism in the numerical model especially at breaking condition.
