Abstract
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.
Highlights
Through industrial development, groundwater resources have been built in rural areas through new land development, groundwater use and river renovation, and this flow has changed water availability due to river regulation in more than half of the world’s rivers [1].due to such development small and medium-sized streams face severe stream drying phenomena because of the distortion of the hydrological circulation system [2].Agricultural reservoirs in small river basins located upstream of rural areas have been severely dried
Agricultural reservoirs are the critical source of water for the supply of irrigation water to paddy fields, and are mainly filled with precipitation during non-irrigation periods, which run from October to the end of March
We attempted to assess the potential impact of agricultural water management in terms of reservoir operation and watershed hydrologic processes
Summary
Groundwater resources have been built in rural areas through new land development, groundwater use and river renovation, and this flow has changed water availability due to river regulation in more than half of the world’s rivers [1].due to such development small and medium-sized streams face severe stream drying phenomena because of the distortion of the hydrological circulation system [2].Agricultural reservoirs in small river basins located upstream of rural areas have been severely dried. Groundwater resources have been built in rural areas through new land development, groundwater use and river renovation, and this flow has changed water availability due to river regulation in more than half of the world’s rivers [1]. Due to such development small and medium-sized streams face severe stream drying phenomena because of the distortion of the hydrological circulation system [2]. To mitigate the stream drying phenomena, including the water quantity and water quality of small and medium-sized streams, environmental flow release (EFR) is necessary
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
