ASSESSMENT OF COASTAL LEVEE HEIGHT USING PROBABILISTIC TSUNAMI HAZARD ASSESSMENT AND ECONOMIC VERIFICATION

Abstract

 In addition to the deterministic tsunami assumptions based on historical tsunamis, a probabilistic approach has been developed for hazard assessment by considering large number of tsunami scenarios. In coastal areas where tsunamis are feared to strike, if levees are raised only based on assumed tsunami height, raised levees may affect the daily life, bread-and-butter job, and use of beach. This study evaluated the maximum inundation depth using a probabilistic tsunami hazard assessment method for the southern coast of Tokushima Prefecture, and the efficient coastal levee height was quantitatively estimated by a costbenefit analysis of coastal levee raising considering the future changes in population and business locations in the hinterland. The results show that the net benefit of levee raising is positive in the areas where population and assets are concentrated and industry is developed. It is confirmed that there are some areas where the benefits can be expected even if the temporary height of levee is raised lower than planned height.