Water Quality Modeling and Evaluation of Nutrient Control Strategies Using QUAL2K in the Small Rivers

Background: Qual2k is a stream water quality model and was used to evaluate the water quality of the Kine-Vars River and assess the response of the river to nutrient management strategies. Methods: For that purpose, 7 sample stations were selected and surface water samples were collected in the winter and summer of 2012 and were analyzed for temperature, dissolved oxygen, biological oxygen demand, ammonia–nitrogen, nitrate–nitrogen, organic nitrogen, organic phosphorus, and inorganic phosphorus. Results: Results showed that the Kine-Vars River is saturated with N and P and is classified as eutrophic. The simulated data showed that the total nitrogen and total phosphorus loads of the studied river need to be reduced by 76% and 93%, respectively, to reach water quality objectives. Conclusion: Application of nutrient control strategies can reduce the nutrient loads significantly but is not sufficient to change the river classification from eutrophic to oligotrophic in a short time; thus, additional nutrient control measures are necessary.