COST-BENEFIT ANALYSIS OF CONSTRUCTION OF COASTAL DEFENSE FACILITIES AND RELOCATION FOR TSUNAMI RISK REDUCTION －CASES STUDY OF OTSUCHI TOWN AND HAMAMATSU CITY－

Abstract

 Since the Great East Japan Earthquake in 2011 occurred, coastal defense facilities such as sea wall have been constructed over Japan. However, the relocation to inland area from the area which is expected to be flooded by tsunami is one of the fundamental measures, but there is an issue that it needs a large amount of money to build new buildings and infrastructures. From the above-mentioned backgrounds, we examined the better way for tsunami risk reduction through the cost-benefit analysis of the construction of coastal defense facilities and the relocation to inland area targeting at Otsuchi Town and Hamamatsu City. As a result of the analysis using the GIS data of anticipated inundation by the administration, the cost-benefit ratio of the former was generally larger than that of the latter in both areas, but we could not immediately conclude that both services have the cost-effectiveness enough to put into action and there is still room for improvement such as downsizing the size of the facilities and implementing the relocation to inland area in the long term leading.