The Effectiveness of Tsunami Walls in Mitigating Tsunami Impact

Abstract Indonesia, an archipelago with the second-longest coastline in the world, is faced with a serious tsunami threat. Therefore, the construction of sea walls is one of the mitigation efforts that need to be considered, and its effectiveness needs to be studied further. The purpose of this study is to examine the hydrodynamic characteristics of tsunami waves when interacting with seawalls through DualSPHysics numerical modeling with the Smoothed Particle Hydrodynamics (SPH) method to understand the effectiveness of seawalls. Tsunami waves are modeled with the dambreak model. Simulations were conducted at model scale with variations in seawall height (Hw) versus reservoir water depth (Ho) at ratios Hw/Ho = 0.00, 0.33, 0.50 and 0.67. Observations focused on the changes in wave speed after seawall overtopping compared to the condition without seawall. The data obtained show that the effectiveness of the seawall in reducing tsunami wave velocity varies depending on the ratio between seawall and tsunami. Higher ratios are generally more effective in reducing the wave speed, but low ratios can lead to an increase in speed under certain conditions. The implementation of the results of this study is illustrated using a scale of approximately 1:50 to illustrate its practical application. This study provides important insights in the design of effective and efficient coastal protection structures for tsunami hazard mitigation in coastal areas of Indonesia.