Document Type : Research Paper
Authors
1 Department of Civil Engineering, University of Zanjan, Zanjan, Iran
2 Assistant Professor, Department of Civil Engineering, University of Zanjan, Zanjan, Iran
Abstract
In this study, by modeling water temperature and some quality parameters using the CE-QUAL-W2 numerical model during different months of the year in the Talvar Dam reservoir, the thermal stratification and mixing times were determined. According to the temperature profile in thermal stratification period, epilimnion, metalimnion and hypolimnion depths were determined. Water quality of the dam reservoir was evaluated using Iran Water Quality Index for Surface Water Resources - Common Parameters (IRWQISC) and Iran Water Quality Index for Surface Water Resources - Toxic Parameters (IRWQIST). For calculation of IRWQISC, some parameters were used including Fecal Coliform, Phosphate, Nitrate, Turbidity, BOD, COD, DO, EC, pH and for calculation of IRWQIST, some parameters were used including Arsenic, Iron, Chrome and Manganese. Considering the effects of thermal stratification on water quality in different points of dam reservoir (hypolimnion, epilimnion) and at different times, a new method was used to evaluate water quality in dam reservoirs based on water quality index. In this method, water quality index was calculated in hypolimnion and epilimnion at different times. In this way, during thermal stratification period of the dam reservoir, the water quality indices were calculated separately for the hypolimnion and epilimnion. Moreover, during mixing period, these indices were calculated for the entire reservoir. Results of the present study showed that water quality of the dam reservoir lied in the relatively good and good class in terms of common parameters (59.9 ≤ IRWQISC ≤ 77), and in the medium and relatively bad class in terms of toxic parameters (30.2 ≤ IRWQIST ≤ 50.2).
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