A STUDY ON COST BENEFIT AND DROUGHT DAMAGE REDUCTION BY A DESALINATION PLANT IN FUKUOKA PREFECTURE

Abstract

 Demands for seawater desalination facilities are increasing all over the world with population increase and economic development. It is important to evaluate the effectiveness of the facilities with respect to water supply and social benefit according to the reduction of drought damages by considering changes in population and water use per capita in the future as well as the facilities' operation cost. This study analyzes cost benefit of a desalination facility in Fukuoka Prefecture namely Mamizu Pia. In particular it compared its social benefit in reducing drought risk in Fukuoka metropolitan area and total cost including the operation cost. The estimated net present value is 48.73 billion yen and cost benefit ratio is 1.66 if we assume 30,000 m³/day of water production by Mamizu Pia. Moreover, with the desalination facility, the most severe water supply restriction in 1978 could be mitigated by 80 % in the daily water supply and almost the same reduction in the drought economic damage.