Proposal of Siphon Operation Guidelines for Reducing Downstream Flood Damage in Small Agricultural Reservoirs

Climate change has altered rainfall patterns, thereby increasing the frequency of extreme floods and threatening small agricultural reservoirs with insufficient discharge facilities. Most reservoirs lack flood control gates, making them vulnerable to excessive inflow. Thus, portable siphons provide a practical alternative. This study used the U.S. Army Corps of Engineers River Analysis System developed by the Hydrologic Engineering Center. (HEC-RAS) to analyze the effects of siphon specifications and pre-release duration on reservoir discharge and downstream inundation, thereby presenting optimized siphon operation guidelines. The results showed that increasing the number of siphons and extending the pre-release periods effectively reduces peak discharge and inundation. Based on these findings, an allowable flood threshold was established to minimize downstream damage and prevent reservoir failure. Site-specific siphon operation standards can enhance emergency discharge systems for aging reservoirs.