Engineering evaluation of hypolimnetic aeration using AEM3D for water-quality improvement in a stratified drinking-water reservoir

Climate warming is intensifying thermal stratification in drinking-water reservoirs, restricting vertical mixing, accelerating hypolimnetic oxygen depletion, and promoting redox-driven nutrient release. To address these challenges, this study evaluated hypolimnetic aeration in Oberon Reservoir (OR), Australia, using field observations (2023–2025) and three-dimensional hydrodynamic and water-quality simulations with the Aquatic Ecosystem Model 3D (AEM3D). The study provides an engineering assessment linking thermal dynamics, oxygen-transfer performance, nutrient suppression, energy consumption, and renewable-energy integration within a stratified drinking-water reservoir. Following calibration and validation under baseline conditions, the model was applied to three operational scenarios: no aeration, continuous aeration (100 L/s; 24 h day −1 ), and solar-powered aeration (100 L/s; 6 h day −1 ). Model performance was strong for water temperature (WT) and dissolved oxygen (DO), with RMSE values below 0.5 °C and 0.3 mg/L, an NSE value of 0.86–0.99, and correlation coefficients exceeding 0.94. Under baseline conditions, persistent stratification restricted oxygen transport, resulting in hypolimnetic oxygen depletion and nutrient accumulation. Continuous aeration increased bottom-water DO from 3.0 to 6.0 mg/L, corresponding to approximately 100% oxygen recovery, while reducing ammonium (NH₄ + –N) and inorganic phosphorus (P) concentrations by 25.8% and 28.1%, respectively. Solar-powered aeration achieved 77% oxygen recovery and maintained substantial water-quality improvements while reducing energy consumption by approximately 75% (1104 to 276 kWh day −1 ) relative to continuous operation. These findings demonstrate that hypolimnetic aeration can effectively suppress anoxia, reduce internal nutrient loading, and improve water quality, while solar-assisted aeration provides a low-carbon and energy-efficient strategy for enhancing reservoir resilience under future climate conditions.