An Empirical Model of Efficiency Analysis on Flood Prevention Investment in Japan

This paper aims to evaluate the comprehensive efficiency of flood disaster prevention investment from 1955 to 1999 by developing and applying an integrated evaluation model. Our analysis results have clarified some important issues currently being discussed in Japan. Firstly, the average values of normalized flood losses decreased greatly between the 1955‐1961 period and the 1984‐1999 period. Secondly, the ratio of human loss to total loss caused by floods in Japan may be less than 10%, based on the concept of the value of statistical life (VOSL) and values estimated from the risk‐money tradeoff. The proportion of intangible effect to total loss increased from less than 10% before the 1970s to approximately 20% after that period. Finally, flood prevention investment in Japan effectively reduced losses caused by flooding before the 1960s; however, since the 1980s, investment has changed from an efficient mode to an inefficient mode, not only from the economic standpoint, but also from that of total flood loss saving.