Abstract
To decide the timing and the method of repair of the irrigation tanks, the method to evaluate the life cycle cost (LCC) of the tank was proposed by using the annual failure probability and the amount of the loss which were derived from the disaster data at Awaji Island in 2004. It was found that as the tank was repaired at the earlier timing, LCC of the tank at the 80th year became lower when a single tank was examined. The effect of LCC was also influenced by the repair cost. As LCC of the multiple tanks in an area, the total LCC became large in the case that the maximum budget became small and the period of repair became long, while the investment effect became high. The uniform annual cost of repair could be planned if the repair of each tank was carried out in a single year or the budget of repair was restrained to relatively small value.
