A MACRO-ANALYSIS OF SEAWALL EFFECTIVENESS IN SMALL COASTAL AREAS

Abstract

 This study provides a comprehensive analysis of the effectiveness of coastal levees in small low-lying areas expected to be impacted by tsunamis originating from the Nankai Trough earthquake. By considering the population of the hinterland protected by levees as a measure of their value, a database was created to assess levee efficiency in numerous small coastal areas using elevation and population mesh data. Inundation heights from tsunami flooding calculations were used to determine the affected population, and this population, divided by the length of the levee, served as an index for levee efficiency. The levee index of each coastal lowland was quantitatively evaluated for varying levee heights. Additionally, the total cost of levee construction was calculated by adjusting levee heights to ensure the levee index was equal across all regions. Key factors affecting levee efficiency were also discussed. This study presents a framework for a macroscopic analysis of the efficiency of coastal levee construction and renewal in small coastal lowlands.