This study aims to develop a reservoir operation rule adding downstream environmental flow release (EFR) to the exclusive use of irrigation water supply (IWS) from agricultural reservoirs through canals to rice paddy areas. A reservoir operation option was added in the Soil and Water Assessment Tool (SWAT) to handle both EFR and IWS. For a 366.5 km² watershed including three agricultural reservoirs and a rice paddy irrigation area of 4744.7 ha, the SWAT was calibrated and validated using 21 years (1998–2018) of daily reservoir water levels and downstream flow data at Gongdo (GD) station. For reservoir water level and streamflow, the average root means square error (RMSE) ranged from 19.70 mm to 19.54 mm, and the coefficient of determination (R²) and Nash–Sutcliffe efficiency (NSE) had no effect on the improved SWAT. By applying the new reservoir option, the EFR amount for a day was controlled by keeping the reservoir water level up in order to ensure that the IWS was definitely satisfied in any case. The downstream mean wet streamflow (Q95) decreased to 5.70 m³/sec from 5.71 m³/sec and the mean minimum flow (Q355) increased to 1.05 m³/sec from 0.94 m³/sec. Through the development of a SWAT reservoir operation module that satisfies multiple water supply needs such as IWR and EFR, it is possible to manage agricultural water in the irrigation period and control the environmental flow in non-irrigation periods. This study provides useful information to evaluate and understand the future impacts of various changes in climate and environmental flows at other sites.

中文翻译：

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考虑韩国农业水库的灌溉水和环境流量，通过修改 SWAT 水库操作来改善下游流量

本研究旨在制定一个水库运行规则，将下游环境流量释放 (EFR) 添加到从农业水库通过运河到稻田区的灌溉水供应 (IWS) 的独家使用中。在土壤和水评估工具 (SWAT) 中添加了一个水库操作选项来处理 EFR 和 IWS。对于包括三个农业水库和 4744.7 公顷稻田灌溉面积的366.5 km ²流域，使用 21 年（1998-2018 年）每天水库水位和贡多 (GD) 站下游流量数据校准和验证了 SWAT。对于水库水位和流量，平均均方根误差 (RMSE) 范围为 19.70 mm 至 19.54 mm，决定系数 (R ²) 和 Nash-Sutcliffe 效率 (NSE) 对改进的 SWAT 没有影响。通过应用新的水库选项，通过保持水库水位上升来控制一天的 EFR 量，以确保在任何情况下都绝对满足 IWS。下游平均湿流流量 (Q95)从 5.71 m ³ /sec下降到 5.70 m ³ /sec，平均最小流量 (Q355)从 0.94 m ³增加到 1.05 m ³ /sec/秒。通过开发满足IWR和EFR等多种供水需求的SWAT水库运行模块，可以在灌溉期管理农业用水，在非灌溉期控制环境流量。本研究为评估和了解其他地点气候和环境流量的各种变化的未来影响提供了有用的信息。