Volume 19, Issue 2 (9-2026)
Iran J Health Environ. 2026, 19(2): 281-298 |
Back to browse issues page
Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:
Ameri Far Z, Jamal A, Nourieh N. Simulation of water quality stress in the Qotur river under low-flow conditions: source
apportionment of point and non-point pollution using the QUAL2Kw model and the IRWQIsc index. Iran J Health Environ. 2026; 19 (2) :281-298
URL: http://ijhe.tums.ac.ir/article-1-7174-en.html
URL: http://ijhe.tums.ac.ir/article-1-7174-en.html
1- Department of Environmental Health Engineering, TeMS.C., Islamic Azad University, Tehran, Iran
2- Department of Environmental Health Engineering, TeMS.C., Islamic Azad University, Tehran, Iran ,n.norieh@iau.ac.ir
2- Department of Environmental Health Engineering, TeMS.C., Islamic Azad University, Tehran, Iran ,
Abstract: (515 Views)
Background and Objective: The Qotur River, the main source of agricultural water in Khoy, faces increasing water quality stress due to urban wastewater discharge. This study aimed to simulate and analyze the water quality stress of this river under low-flow conditions using the QUAL2Kw model and the IRWQIsc index.
Materials and Methods: The study was conducted over a 38.92-km reach of the Qotur River with five main stations and two point sources (the Khoy wastewater treatment plant outlet and the Qareh-Sou River). Sampling was carried out during two low-water periods (November and December 2024), and parameters including DO, BOD₅, COD, NH₄⁺, EC, and FC were measured. The QUAL2Kw model was run with manual calibration and validation.
Results: The model showed acceptable accuracy in reproducing observed data (RMSE for DO and BOD₅ were 1.46 and 1.73 mg/L, respectively). After the point source inputs, downstream BOD₅ and NH₄⁺ increased to 33 mg/L and 5600 µgN/L, respectively, while DO decrease to 7.3 mg/L. A 79 percent reduction in discharge and non-point source inputs (livestock farming) were identified as the primary factors sustaining the pollution, and non-point sources accounted for 75 percent of the increase in downstream BOD₅.
The geometric mean of the IRWQIsc index in the two periods was 33.01 and 30.93 (classified as "relatively poor"), declining to "poor" at the terminal stations. Ammonium and fecal coliforms contributed the most to the reduction of the index.
Conclusion: Providing environmental flow and controlling livestock runoff are essential measures to improve the water quality of the Qotur River.
Materials and Methods: The study was conducted over a 38.92-km reach of the Qotur River with five main stations and two point sources (the Khoy wastewater treatment plant outlet and the Qareh-Sou River). Sampling was carried out during two low-water periods (November and December 2024), and parameters including DO, BOD₅, COD, NH₄⁺, EC, and FC were measured. The QUAL2Kw model was run with manual calibration and validation.
Results: The model showed acceptable accuracy in reproducing observed data (RMSE for DO and BOD₅ were 1.46 and 1.73 mg/L, respectively). After the point source inputs, downstream BOD₅ and NH₄⁺ increased to 33 mg/L and 5600 µgN/L, respectively, while DO decrease to 7.3 mg/L. A 79 percent reduction in discharge and non-point source inputs (livestock farming) were identified as the primary factors sustaining the pollution, and non-point sources accounted for 75 percent of the increase in downstream BOD₅.
The geometric mean of the IRWQIsc index in the two periods was 33.01 and 30.93 (classified as "relatively poor"), declining to "poor" at the terminal stations. Ammonium and fecal coliforms contributed the most to the reduction of the index.
Conclusion: Providing environmental flow and controlling livestock runoff are essential measures to improve the water quality of the Qotur River.
Send email to the article author
| Rights and Permissions | |
 |
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. |
