Irrigation and Water Engineering

Irrigation and Water Engineering

Simulation of Thermal Stratification and Dissolved Oxygen Dynamics in the Zayandeh-Rud Reservoir under Inflow Variation Scenarios Using the CE-QUAL-W2 Model

Document Type : Original Article

Authors
Seyedeh Hadis Shahrokhi 1
Hassan Torabi podeh 2
Amir Hamzeh Haghiabi 3
Pooneh Saeidi 4
1 Candidate in Hydraulic Structures, Department of Water Engineering, Faculty of Agriculture, Lorestan University,
2 Ph.D. Student In Water Structure of Lorestan University, Khorramabad, Iran
3 Professor, Department of Water Engineering, Faculty of Agriculture, Lorestan University
4 . PhD. Environmental Science/Engineering Water Resources track, Tarbiat Modares University
10.22125/iwe.2026.584109.1925
Abstract
Dissolved oxygen and thermal stratification are among the most critical parameters controlling water quality and ecosystem stability in reservoir systems. In arid and semi-arid regions, these processes are intensified by drought, climate change, and particularly declining water levels and reduced inflows. In the present study, the thermal and oxygen responses of the Zayandeh-Rood Reservoir to inflow variations were investigated using the two-dimensional longitudinal-vertical numerical model CE-QUAL-W2. The primary objective of this study was to assess the impact of inflow reduction on reservoir water level, thermal stratification stability, the vertical distribution of dissolved oxygen (DO), and the identification of critical elevations associated with severe water quality deterioration. The model was calibrated and validated using observational data from the 2020–2021 water year.The results indicated that the water level simulation achieved high accuracy after correcting the reservoir bathymetry (stage-volume relationship) and optimizing parameters, yielding a Mean Absolute Error (MAE) of 2.7 cm" and a Root Mean Square Error (RMSE) of 3.3" cm" . Furthermore, the model demonstrated excellent agreement with observed values during thermal and dissolved oxygen calibration; for temperature, the MAE and RMSE reached 0.64^∘ C and 0.81^∘ C , respectively, while for dissolved oxygen, the MAE and RMSE values were 0.89mg/L and 1.12mg/L , respectively.
Keywords
Zayandeh-Rud Reservoir
:thermal stratification:Residence time: climate change
: CE-QUAL-W2
Subjects
 
Adrian, R. O. Reilly., H. Zagarese, S. B. Baines, D. O. Hessen, W. Keller. and G. A. Weyhenmeyer. 2009. Lakes as sentinels of climate change. Limnology and Oceanography, 54(6), 2283-2297.
Azadi, F., P.-S. Ashofteh, and X. Chu. 2020. Evaluation of the effects of climate change on thermal stratification of reservoirs. Journal pre-proof.
Cole, T. M., and S. A.  Wells. 2015. CE-QUAL-W2: A hydrodynamic and water quality model for rivers, estuaries, lakes, and reservoirs. Version 3.7. US Army Corps of Engineers.
Ebrahimi, M., E. Jabbari, H. Abbasi. et al. 2015. Simulation of thermal structure in Baft Dam reservoir using CE-QUAL-W2. Journal of Civil Engineering and Urbanism, 5(1), 07-11.
IPCC. 2021. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the. Intergovernmental Panel on Climate Change.
Jane, S. F., G.J. Hansen, B.M. Kraemer, P.R. Leavitt, J.L. Mincer, R.L. North, and R.I. Woolway. 2021. Widespread deoxygenation of temperate lakes. Nature, 594(7861), 66-70.
Mi, C., T. Shatwell, J. Ma, Wentzky, B. Xu. Y. Boehrer, K. Rinke. 2020. The formation of a metalimnetic oxygen minimum exemplifies how ecosystem dynamics shape bio- geochemical processes: a modelling study. Water Res.
Noori, R., R. Berndtsson, J. F. Adamowski, and M. Rabiee Abyaneh. 2018. Temporal and depth variation of water quality due to thermal stratification in Karkheh Reservoir, Iran. Journal of Hydrology: Regional Studies, Volume (19), 279–286.
O’Reilly, C. M., S. Sharma, D. K. Gray, S. E. Hampton, J. S.Read, R. J.Rowley, and G. Zhang. 2023. Rapid and highly variable warming of lake surface waters around the globe. Nature Climate Change, 13(5), 456-464.
Sadeghian, A., S.C. Chapra, J. Hudson, H. Wheater, K.-E. Lindenschmidt. 2018. Improving in-lake water quality modeling using variable chlorophyll a/algalbiomass ratios. Environ. Modell. Softw. 101, 73–85.
Wetzel, R. G. 2001. Limnology: Lake and River Ecosystems (3rd ed.). Academic Press.
Woolway, R. I., and C. J. Merchant, 2019. Amplification of lake surface warming by lake size: Implications for high-latitude lake eutrophication. Geophysical Research Letters, 46(1), 162-171.
Woolway, R. I., S. Sharma, G. A. Weyhenmeyer, A. Creighton, T. Shatwell, and J. D.Lenters. 2021. Phenological shifts in lake stratification under climate change. Nature Communications, 12(1), 2318.
Zhang, Y., X. Liu, and, J. Chen. 2022. Reservoir sediment nutrient release under hypoxia: A review of mechanisms and controlling factors. Journal of Environmental Management, 318, 115598.
Ziaei, M., B. Mohammadnezhad, M. Taheriyoun, A. Karimi, and S. Amiri. 2019. Evaluation of eutrophication in Zayandeh-Rood Dam reservoir using numerical modeling. Journal of Environmental Science and Technology, 21(5), 112-126.