Enhancing Agricultural Water Management with SWMM: A Comparative Analysis of Gate Control Strategies in South Korea

Efficient management of agricultural irrigation is increasingly important amid growing climate-driven water challenges. This study aims to propose various modeling approaches for estimating agricultural water usage, demand, and return flow using the Storm Water Management Model (SWMM). A comprehensive assessment of the agricultural water distribution was conducted by considering factors such as water supply, demand, irrigation return flow, and water deficit. The study area consisted of four reservoirs situated in different regions of South Korea's four major river basins that reflect a variety of hydrological and irrigation conditions. The SWMM simulates an agricultural water supply and distribution network based on data such as rainfall, evapotranspiration, infiltration, and canal losses. Two water management scenarios were examined: Scenario A, which represents a conventional, non-optimized irrigation operation in which water distribution follows fixed, rule-based allocations without any dynamic control or feedback mechanisms, and Scenario B, in which gate operations were scheduled and controlled according to empirical operational guidelines to improve the efficiency of water distribution. The results indicate that Scenario B significantly enhanced the water distribution efficiency, leading to increased ponding depth rates and reduced water deficits. Additionally, the irrigation return flow was reduced in Scenario B, demonstrating improved water-use efficiency. The analysis highlights the importance of systematic water management strategies, such as gate control regulations, to stabilize the water supply in agricultural areas. These findings provide valuable insights into policy development and practical applications of sustainable agricultural water management.