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Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering ENVE5504 Surface Water Quality Modeling Lab 4. One-Dimensional Models Vertical Mass Transport in Dollar Bay, Michigan
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8 8 Lake Superior – 8/25/00 Vertical Resolution: Lake Superior
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Temperature and the Density of Water 1.0000 0.9995 0.9990 0.9985 0.9980 0.9975 0.9970 0.9965 0.9960 0.9955 0.9950 Density (g∙cm 3 ) 0 5 10 15 20 25 30 Temperature (°C) Maximum Density 3.94 °C
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Thermal Stratification spring summer Temperature (°C)
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Thermal Stratification
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Seasonality in Stratification and Mixing = °C
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Dollar Bay - Temperature 0 1 2 3 4 5 6 7 8 Depth (m) 0 5 10 15 20 Temperature (°C) 0 1 2 3 4 5 6 7 8 Depth (m) M A M J J A S O N D
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Productivity and Oxygen
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Trophic State and Oxygen Profiles Oligotrophic Lake Eutrophic Lake Temperature (°C)
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Dollar Bay - Temperature 0 1 2 3 4 5 6 7 8 0 5 10 15 20 Temperature (°C) 0 1 2 3 4 5 6 7 8 Depth (m) M A M J J A S O N D
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Dollar Bay – Dissolved Oxygen Depth (m) 0 1 2 3 4 5 6 7 8 0 2 4 6 8 10 12 Dissolved Oxygen (mg∙L -1 ) M A M J J A S O N D
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Onondaga Lake – Dissolved Oxygen
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Oneida Lake – Dissolved Oxygen
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Lake Erie – Dissolved Oxygen
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Gulf of Mexico – Dissolved Oxygen
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8 8 Lake Superior – 8/25/00 Vertical Resolution - Stratification
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Vertical Mass Transport
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Application to Vertical Mass Transport turbulent diffusion coefficient thermocline heat transfer coefficient
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Calculation of the Thermocline Heat Transfer Coefficient Epilimnion Heat Balance change in heat tributary heat in discharge heat out surface heat flux thermocline heat exchange
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Calculation of the Thermocline Heat Transfer Coefficient Hypolimnion Heat Balance change in heat thermocline heat exchange assumes no direct heating of hypolimnion or sediments upper mixed layer (~epilimnion) lower mixed layer (~hypolimnion) thermoclinev t ∙A s
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Calculation of the Thermocline Heat Transfer Coefficient Canceling the and C p terms, dividing by V h and expanding … And defining … Yields … uml lml
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Calculation of the Thermocline Heat Transfer Coefficient and re-arranging, yields … Which, for T h at the beginning of the calculation = Th i, yields … further re-arranging, yields … where a plot of t s versus term yields 1/v t as the slope term
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Application to Dollar Bay
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Dollar Bay - Temperature 0 1 2 3 4 5 6 7 8 0 5 10 15 20 Temperature (°C) 0 1 2 3 4 5 6 7 8 Depth (m) M A M J J A S O N D
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Dollar Bay – Dissolved Oxygen Depth (m) 0 1 2 3 4 5 6 7 8 0 2 4 6 8 10 12 Dissolved Oxygen (mg∙L -1 ) M A M J J A S O N D
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For diffusion calculation, need to choose an interval where T e is stable and T h is warming. Dollar Bay – Temperature Calculations Hypolimnion temperature mass balance.
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Sediment oxygen demand reflects the diffusion of oxygen into the sediment to meet the metabolic needs of microorganisms participating in the aerobic decomposition of organic matter. SOD is also exerted through the aerobic oxidation of reduced species byproducts of anaerobic respiration. The mass balance, for SOD alone is … Sediment Oxygen Demand uml lml
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For the SOD calculation, we need to choose the interval of oxygen depletion. Dollar Bay – Oxygen Calculations
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Time-Variable vt Values for Onondaga Lake (Doerr et al. 1996)
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