Qualitative and quantitative assessment of reservoir water resources under the eutrophication using CE-QUAL-W2

Abstract

This study examines the eutrophication phenomenon in the Ekbatan Dam (Hamadan, Iran) under 11 qualitative–quantitative scenarios. The two-dimensional model CE-QUAL-W2 was used to simulate the hydrodynamics and water quality parameters of the reservoir from 2019 to 2020. After assessing the current state of eutrophication in the Ekbatan Dam, eleven scenarios were analyzed, including reductions in inflow, outflow, and input pollutants. The results indicate that phosphate reduction under scenarios 9, 10, and 11 is minimal, while the highest phosphorus levels occur in scenario 8, where the inflow rate is reduced by 45%. Additionally, the findings suggest that eutrophication risks remain high from autumn to late February, with elevated phosphate concentrations observed. A 15% reduction in phosphorus input (scenario 9) leads to a notable decrease in phosphate levels compared to the current state of the reservoir. The lowest nitrate levels are observed in scenarios with reduced inflows and pollutant inputs, whereas the highest nitrate concentrations are associated with scenario 8. Overall, scenarios involving a 15% reduction in phosphorus and nitrate demonstrate better outcomes for mitigating eutrophication in the reservoir. These findings highlight the importance of studying and managing phosphorus to control the eutrophication process in the Ekbatan reservoir.