Scenario‐based water balance analysis of estuary reservoir for multipurpose water supply

Abstract In the circumstance of increasing industrial and municipal water demand, estuary reservoirs are one of the critical water resources that can be a solution. Therefore, we simulated the water balance model of an estuary agricultural reservoir to evaluate the impact of additional industrial water release on its performance. We considered runoff and treated water as water inflow and irrigation requirement in paddy fields and water use in the hydrogen plant as water release. Runoff and irrigation water requirements were estimated using the Tank model and the FAO modified Penman method, respectively. Industrial water demand was surveyed at 32,000 m 3 day −1 throughout the year. The results show that the reservoir's reliability increases as the water loss and irrigation area decrease with reusing the return flow, which is hardly affected by the industrial water supply. The trend of resiliency resembles reliability; however, the industrial release has the most significant impact when lower water loss is applied and the paddy area is decreased. Vulnerability gets worse when additional purpose water is released. In other words, the more water the reservoir releases, the more severe the drought gets. Therefore, the engineer and operator should consider the expected risks presented as reliability, resiliency and vulnerability in the design and management of the reservoir.