Canal Flow
This category controls how the flow through the canal is calculated. Two of the user methods in this category are implementations of canal flow equations used by TVA. The Canal Flow Table method is the only generic method that can be used for canals other than the Tellico and Barkley Canals in the TVA system.
NoneThis method is the default for this category. It results in an error if it is selected and a run is begun.
There are no slots specific to this method.
Canal Flow TableThis method is a general method that can be used to solve any canal whose flow can be described using the Canal Flow Table. This method takes the average pool elevation of the lower Reservoir and the difference in average elevation between the two Reservoirs and uses linear interpolation to determine Canal Flow from the Canal Flow Table.
Slots Specific to This Method
Delta Elevation
Type: AggSeriesSlot
Units: Length
Description: Average elevation difference between the two reservoirs for the current timestep
I/O: Output only
Links: Not linkable
Lower Elevation
Type: SeriesSlot
Units: Length
Description: The average elevation of the lower reservoir for the current timestep
Information: This slot is necessary because the height of the water in the canal effects the flow rate.
I/O: Output only
Links: Not linkable
Canal Flow Table
Type: TableSlot
Units: Length, Length, Flow
Description: Three-dimensional table used to find canal flow by interpolation
Information: First column is Lower Elevation (can have several entries with the same lower elevation); second column is Delta Elevation; third column is Canal Flow. This table provides information regarding several possible Lower Elevation and Delta Elevation values and the corresponding Canal Flow at these operating points.
I/O: Input only
Links: Not linkable
Elevation 1 Adjustment
Type: ScalarSlot
Units: Length
Description: Adjusts the Elevation 1 value by a user-specified amount.
Information: Automatically set to zero if not input. This slot was added to handle the Barkley Canal calculations. This slot is not necessary for most users.
I/O: Optional; defaults to zero if not input
Links: Not linkable
Method Details
Note: The canal flow solution requires that the slot minimum and maximum be set in the Pool Elevation slot configuration on both linked reservoirs. Also the quality of the solution for Canal Flow is sensitive to the slot convergence values in the slot configuration for all series slots on the Canal object. It is recommended that the slot convergence be set to 0.00001 Percent for all Canal series slots.
1. The method checks to see if an Elevation 1 Adjustment value is given. If no value is input, Elevation 1 Adjustment is set to zero; otherwise, the Elevation 1 value is adjusted by the given amount.
2. Delta Elevation is computed as follows.
abs(average elevation 1 - average elevation 2)
3. Lower Elevation is set to the lower value of either average elevation 1 or average elevation 2.
4. Once Delta Elevation and Lower Elevation are known, the Canal Flow can be found directly from the Canal Flow Table. The appropriate direction of flow is determined based on the average elevation of the two reservoirs.
– A negative flow implies flow out of the Reservoir.
– Flow is from the reservoir with the higher average elevation to the reservoir with the lower average elevation.
Tellico Canal EquationThere are no slots specific to this method.
Note: The canal flow solution requires that the slot minimum and maximum be set in the Pool Elevation slot configuration on both linked reservoirs. Also the quality of the solution for Canal Flow is sensitive to the slot convergence values in the slot configuration for all series slots on the Canal object. It is recommended that the slot convergence be set to 0.00001 Percent for all Canal series slots.
The basic equation for this method is in user units:
• FlowLower
Flow into the reservoir with the lower pool elevation (in cfs).
• hlower
Pool Elevation of the lower reservoir (in feet).
• hdiff
Absolute value of difference in Pool Elevation between the two reservoirs (in feet).
If the difference in Pool Elevation is smaller than 0.01 feet, a linearized version of this equation is used.
Barkley Canal EquationThere are no slots specific to this method.
Note: The canal flow solution requires that the slot minimum and maximum be set in the Pool Elevation slot configuration on both linked reservoirs. Also the quality of the solution for Canal Flow is sensitive to the slot convergence values in the slot configuration for all series slots on the Canal object. It is recommended that the slot convergence be set to 0.00001 Percent for all Canal series slots.
The basic equation for this method is in user units.
• FlowLower: Flow into the reservoir with the lower pool elevation (in cfs).
• hlower: Pool Elevation of the lower reservoir (in feet).
• hdiff: Absolute value of difference in Pool Elevation between the two reservoirs (in feet).
If the difference in Pool Elevation is smaller than 0.01 feet, a linearized version of this equation is used.
Barkley must be connected to the Reservoir 1 slots, Flow 1 and Elevation 1. This requirement is due to an adjustment of -0.08 feet made to Elevation 1 because of physical considerations.
Revised: 08/02/2021