Description

The maximum combined outflow of a reservoir, including outlet works or turbine release, and any possible regulated, unregulated, and/or bypass spills.

Type

NUMERIC

Arguments

Type

Meaning

1

OBJECT

the reservoir object for which to calculate

2

NUMERIC

the end of timestep pool elevation (HW or headwater)

3

DATETIME

the timestep at which to calculate

Evaluation

This function calls the getMaxOutGivenHW() function on the given reservoir object at the given timestep, and provides it with the end of timestep pool elevation. This ending HW is averaged with the previous timestep’s ending Pool Elevation to yield an average HW over the timestep. The average HW is then used to compute the following outflows:

• release (if the object is a StorageReservoir): The maximum release is determined from a table interpolation in the Max Release table using the average HW as the lookup in the Pool Elevation column.
• turbine release (if the object is a LevelPowerReservoir or SlopePowerReservoir): The maximum turbine release is determined based on the selected PowerCalculationCategory Method. This calculation is iterative, since the maximum outflow impacts the reservoir tailwater elevation and operating head, which affect the maximum turbine release. The selected tailwaterCalculationCategory Method is used to determine the tailwater elevation.
• No Power Turbine Flow : The turbine release is determined from a table interpolation in the Max Flow Through Turbines table using the average HW as the lookup in the Reservoir Elevation column.
• plantPowerCalc : The turbine release is determined from a table interpolation in the Max Turbine Q table using the operating head as the lookup in the Operating Head column. If the average HW is less than the Minimum Power Elevation , the turbine release is zero.
• unitGeneratorPowerCalc : The turbine release is the sum of the maximum releases for each available turbine, as specified in the Generators Available and Limit table. Each turbine’s maximum release is determined from a table interpolation in the Full Generator Flow table using the
• unregulated spill (if an unregulated spillway Method is selected on the object): The maximum unregulated spill is determined from a table interpolation in the Unregulated Spill Table using the average HW as the Pool Elevation .
• regulated spill (if a regulated spillway Method is selected on the object): The maximum regulated spill is the user input Regulated Spill at the given timestep or is determined from a table interpolation in the Regulated Spill Table using the average HW in the Pool Elevation column. Note, if the MonthlySpillCalc Method is selected, the result of getMaxOutflowGivenHW is the value in the Maximum Controlled Release table slot.
• bypass (if a bypass spillway Method is selected on the object): The maximum bypass is the user input Bypass at the given timestep or zero, if no bypass is input.
• All of the individual outflows are then summed to calculate the maximum outflow.

Evaluation cont.

• operating head as the lookup in the appropriate unit type’s Head for Type n column. If the average HW is less than the Minimum Power Elevation, the turbine release is zero.
• PeakPowerCalc and PeakBasePowerCalc : The turbine release is the peak flow over the entire timestep. This is calculated by iterating the selected tailwaterCalculationCategory Method and operating head calculation with a table interpolation in the Best Generator Flow table using the operating head as the lookup in the Head for Type 1 column.
• LCRPowerCalc : Because this power Method has no turbine release limit, a maximum Outflow cannot be calculated. RiverWare issues an error message and aborts the execution of this rule.

Mathematical Expression

Comments

The Tailwater Base Value is added as an automatic dependency of this function. Since the function evaluation depends on this slot, any change to its values, may impact the function result.