Abstract
In the absence of a reservoir on the downstream side, river flow which increases temporarily by rainfall cannot be stored and discharged apart from requirement in the beneficial area. This unused water (excess water) occurs to some degree even in a draught year and effective use of this supply is considered as one of the countermeasures for water shortage. Setting up a regulating reservoir on the upstream side of head works is regarded as one of the methods to make effective use of excess water. The inflow to the river and water delivery loss which occurs from rainfall are stored in the regulating reservoir and supplied to the beneficial area on the downstream side as agricultural water. It is thought that the effect is achieved by increasing the cycles of the storage and discharge in a short term, though the capacity of regulating reservoir is smaller in comparison to the dam. In this study, the excess water was calculated for a canal system which has a water shortage tendency, and an operational method for the regulating reservoir to effectively utilize this excess water was examined by simulation.
