農業用水の効率的配分を実現する「弾力的用水供給モデル」の提案

抄録

Irrigation water demand has tended to be concentrated during certain hours of the day, particularly in the morning and the evening, in response to an increase in the number of part-time farmers. On the other hand, the volume of supplied water is customarily fixed all day regardless of the fluctuation in demand. This results in a temporal and spatial imbalance of supply and demand, that is, a short supply occurs in the downstream area during the peak demand hours, despite the excessively supplied water is wasted during the low demand hours. In this study, authors proposed an “elastic water supply model” to realize more efficient irrigation water distribution and saving the usable water resource. The model was applied to the study field, K river basin, S city, Niigata prefecture, where water resource is chronically tight for the size of the beneficiary area of the irrigation water. The model evaluation was conducted by numerical simulation performed on the basis of the field survey concerning the time-series water demand fluctuation and arrival time of irrigation water. The result shows that the elastic water supply model functions to satisfy the peak demand requirement as well as to save water resources by 33% under the condition of installing regulating ponds with an appropriate capacity in the midstream of trunk irrigation channels for the sake of compensating the delay in the arrival of irrigation water.