Hydrodynamic and Water Quality Modeling for Sustainable Aquaculture Practices

Best management practices are critical for mitigating the detrimental effects of aquaculture on water quality under climate change. This study evaluates the effectiveness of wastewater management practices from 11 flow-through trout farms and their impact on the water quality of the Aras River. The river has experienced a notable increase in nutrient concentrations, largely due to high discharges of nutrients and suspended solids from intensive aquaculture operations. A hydrodynamic and water quality model was used to predict and manage pollution from trout farms under various applicable scenarios, showing excellent agreement with observed data. Our approach uniquely integrates rigorous hydrodynamic modeling with field data from 11 trout farms, enabling a robust scenario-based assessment of management strategies. Key scenarios simulated include variations in river flow and adjustments in farm production capacities. The most effective strategy resulted in increasing river flow (e-flows) while reducing trout farms’ production capacity. Specifically, a 25% increase in river discharge reduced nitrate-nitrogen (NO ₃-N) and phosphate-phosphorus (PO ₄-P) concentration by 37 and 16.7%, respectively, while a 50% reduction in trout farm production capacity significantly improved downstream water quality. These quantitative outcomes offer insights into scalable, effective nutrient pollution control, underscoring the need for improved capacity planning, sustainable practices, and holistic management of land-based aquaculture systems.