Feasibility of Low Water Level Management in Irrigation Ponds: Focusing on Baseflow and Water Storage Recovery Periods in Oro River Basin, Tottori

抄録

Japan has about 150,000 irrigation ponds, primarily located in areas with low rainfall and regions lacking nearby rivers. These ponds primarily supply irrigation water for paddy fields and serve as year-round sources of domestic and fire-fighting water. In recent years, Japan has experienced an intensification and increase in the frequency of heavy rainfall events from summer to autumn (July to September), leading to an increase in the number of water-related disasters. These irrigation ponds have also suffered an increase in disasters caused by heavy rainfall. To address this issue, one of the flood control methods for irrigation ponds is "low-water-level management". By maintaining lower water levels, it is expected that the risks of dike breaches due to overtopping will be minimized, and peak flow from the spillway will also be mitigated. However, implementing low-water-level management may lead to the potential risk of not being able to secure a sufficient water supply for irrigation. This study evaluated the feasibility of implementing low-water-level management across 52 irrigation ponds in the Oro River Basin in Tottori City, Tottori Prefecture. We calculated the recovery period for water storage using only baseflow to determine whether it is possible to maintain low water levels without compromising the necessary water supply. The results indicate that low-water-level management can be implemented in many ponds without significant concerns regarding water availability, supporting its potential as a flood control measure.