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Water Quality : Reservoir Water Quality : User Methods : WQ Distribute Outflow
WQ Distribute Outflow
This category of methods is only applicable to the layered methods. These methods allow the user to model the physical character of the outlet works of the reservoir. This is crucial for accurate tracking of release temperatures, DO levels, etc.
* None
This is the default method and is not a valid method for calculation. An error is flagged if this method executes. This method does not instantiate any water quality slots.
* Zone of Influence
No slots are explicitly instantiated by this method but the following slots are used as a part of the calculation.
 Reservoir Length
Type: Table Slot
Units: Length
Description: 1X1 table slot representing the length of the reservoir
I/O: Required Input
 Reservoir Bottom Elevation
Type: Table Slot
Units: Length
Description: 1X1 table slot representing the elevation (above some common datum) of the bottom of the reservoir at the dam
Information: Used to calculate a mean depth at the dam.
 Release Elevation
Type: Table Slot
Units: Length
Description: 1X1 table slot representing the elevation (above some common datum) of the outlet works.
I/O: Required Input
 Thickness of Epilimnion
Type: Table Slot
Units: Length
Description: 1X1 table slot representing the thickness of the epilimnion layer
I/O: Must be input by user.
 Reservoir Geometry Coefficients
Type: Table Slot
Units: NoUnits
Description: table of coefficients which represent the a1, a2, a3, a4 coefficients.
I/O: If not input, they are generated by the function cubicFit.
 Withdrawal Zone Coefficient
Type: Table Slot
Units: NoUnits
Description: 1x1 table of a single coefficient to represent cone of influence around outlet works.
I/O: If not input, it is set to 1.0.
Slots With Required Known Data
• Outflow
• Reservoir Length
• Reservoir Bottom Elevation
• Thickness of Epilimnion
• Release Elevation
• Withdrawal Zone Coefficient
• Reservoir Geometry Coefficients Table
Slots With Output Data
• Outflow from Epilimnion
• Outflow from Hypolimnion
The method, Zone of Influence, uses a cubic function (user input coefficients or calculated from the elevation-volume table), the magnitude of the outflow, and the release elevation to define a “zone of influence” from which the outflow is taken. The fraction of total outflow attributed to the epilimnion and hypolimnion is reflected by the values set in the Outflow from Hypolimnion and Outflow from Epilimnion slots.
* Specify Outflow Fraction
This method allows you to distribute the outflows using a series of fractions with a periodic input. The following slot is added by this method.
The distribution is computed as follows:
(14.5)    Outflow from Hypolimnion = Outflow from Hypolimnion Fraction * Total Outflows
(14.6)    Outflow from Epilimnion = Total Inflows - Outflow from Hypolimnion;
 Outflow from Hypolimnion Fraction
Type: Series with Periodic Input
Units: Fraction
Description: The fraction of the total outflow that leaves the Hypolimnion
Information: The value must be specified and the value must be between 0 and 1, inclusive.
I/O: Required via input or Rules
Revised: 11/11/2019