Within the Nutrient Options and Parameters frame (2217607194) settings for many of the basic nutrient parameters may be made. The nutrient parameters have been grouped by nutrient type and can be edited by clicking on the respective button. For example, the user would click on the Nitrogen button to edit the nitrogen default settings. If the user implements kinetic zones then those values will be used in place of these values, however, the default values are still displayed in this form. For example, this can mean that the COD decay rate may be different in two places, however, the kinetic zone value will take precedence.
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Figure 1. Water Quality tab: Nutrients.
The user may also specify the Sorption Options. The default is "None" and parameters cannot be modified. However, if Total Active Metal (TAM) Based or Cohesive Sediment Based radial buttons are selected, the user may alter these nutrient sorption parameters with the Modify Parameters button.
The atmospheric wet deposition concentrations for the constituents being simulated with the kinetic module selected are edited via the Wet Deposition button. The dry deposition mass fluxes are edited via the Dry Deposition button.
The user can also configure reaeration options Open General Options by RMC on the Water Quality module and select General Options (Figure 1).
Dry Deposition and Wet Deposition are boundary conditions in the Water Quality module. The concentrations of water quality components from both boundary conditions are included in the EFDC+ computations. By default, these concentrations are initially set to zero and can be modified using EFDC+ Explorer. The following steps explain how to change the atmospheric deposition conditions.
In the Atmospheric Deposition section, the user can modify the concentrations of different water quality components. To do this, LMC on the Dry Deposition or Wet Deposition buttons (Figure 4) then input non-zero values in the table displayed in which the water quality parameters are shown. Click OK to save changes.
Click OK to close the General Options option, then save the model.
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Figure 4: Wet and Dry Deposition settings
EE will automatically initialize the water quality module using values in the code. However, it is often convenient to initialize a new model using data from another EFDC+ Explorer model with similar conditions. This is done using the Initialize WQ Parameters from File in the Miscellaneous frame as shown in Figure 5. This operation should only be conducted once at the start of the water quality model construction. This process overwrites all of the current model's settings.
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Figure 5. Miscellaneous frame.
The user can also configure reaeration options (Figure 6) in this frame. The drop-down menu provides 5 options, including constant (WQKRO), constant + wind-generated, O'Connor-Dobbins (1958), Owens & Gibbs (1964), and Owens & Gibbs (modified). Each option will assign a default reaeration value.
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Figure 6. Reaeration options.
The saturation concentration of DO in water increases as pressure increases. This means that water at lower altitudes can hold more dissolved oxygen than water at higher altitudes. Allowance for the effect of elevation on the DO of the waterbody to DO, can be set in DO Saturation Options frame (Figure 7) The user can select different options from the drop-down list of the Formulation option. Options include Garcia and Gordon (1992), Chapra et al. (1997), and Genet et al. (1974). There are three options in the Elevation Adjustment drop-down, including to not use using the elevation adjustment, as well as the Chapra et al. (1997), and Zison et al. (1978) adjustments.
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Figure 7. DO Saturation Options
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