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Objects and Methods : Reservoir Methods : User Methods : Operating Levels
Operating Levels
This category enables the user to specify operating levels for the reservoir. Operating levels serve as a normalizing metric for reservoir contents. This metric is used by reservoir-balancing algorithms to determine the relative “fullness” of reservoirs. On individual reservoirs, it also serves to identify the elevations that correspond to pool boundaries, such as the top of the conservation pool or the top of the flood pool.
* None
This is the default method; no slots are instantiated and no calculations are performed.
* Conservation Pools
This method allows the user to specify that there is a conservation pool for this reservoir.
Slots Specific to This Method
 Operating Level Table
Type: PeriodicSlot
Units: Time vs Length at Operating Levels
Description: Table describing the seasonal variation of elevation in a reservoir at each of the user-designated operating levels.
Information: number of rows defined by the number of date points (user input); number of columns defined by the number of operating levels (user input). Each column represents the time-varying elevations for a particular Operating Level. The integer value of the Operating Level is in the first row (header) of each column. An elevation value is input for each operating level on each date point. All entered values have units of length. User can select whether to interpolate between values in time, or to have constant values until the next timestep.
I/O: Required input
 Operating Level
Type: SeriesSlot
Units: None
Description: The computed operating level
Information: This slot is computed using the pool elevation and the Operating Level Table
I/O: Output only
 Operating Level Storage Table
Type: PeriodicSlot
Units: Time vs Volume at Operating Levels
Description: Table describing the seasonal variation of storage in a reservoir at each of the user-designated operating levels.
Information: Each column represents the time-varying storage for a particular Operating Level. The integer value of the Operating Level is in the header of each column. This table is generated from the Operating Level Table and has the same number of rows and columns. The values in the table are storage values (looked up from the elevation volume table) whereas the values in the Operating Level Table are elevations. This slot is computed at run-time so it is read-only to the user. All changes should be made in the Operating Level Table.
I/O: Output only
 Top of Conservation Pool
Type: ScalarSlot
Units: None
Description: Operating level (as defined in Operating Level Table) corresponding to the top of the conservation pool.
Information:  
I/O: Input
 Bottom of Conservation Pool
Type: ScalarSlot
Units: None
Description: Operating level (as defined in Operating Level Table) corresponding to the bottom of the conservation pool.
Information: Used by some conservation pool operations algorithms, along with the Top of Conservation Pool slot, to identify the volume in the conservation pool.
I/O: Input only
 Conservation Pool Initial Empty Space
Type: SeriesSlot
Units: None
Description: The inflow required to fill the conservation pool at the beginning of timestep, based on the ending storage at the prior timestep, taking into account evaporation, precipitation, and so on.
Information: This slot is computed at the beginning of the timestep; evaporation rates and other such factors that are not already defined at the beginning of timestep will not be taken into account in this computation. This slot is used by the water rights allocation solution algorithm to compute physical constraints and by storage accounts to compute allocation requests.
I/O: Output only
 Conservation Pool Storage
Type: Series
Units: Volume
Description: This is the computed volume of water in the conservation pool.
Information: This value is always non-negative.
I/O: Output only
 Conservation Pool Full Storage
Type: Series
Units: Volume
Description: This is the possible volume of water that could be stored in the Conservation pool. It is computed as the Storage at the top of the conservation pool minus the storage at the bottom of the conservation pool
Information:  
I/O: Output only
 Conservation Pool Storage Fraction
Type: Periodic Slot
Units: Fraction
Description: The values in the periodic slot represent the percentage of the conservation pool storage at each level (column) in the Operating Level Table.
Information: It has identical dimension including dates and levels as the Operating Level Table. This table will be populated at beginning of run. The Operating Level Table will be its “source” slot.
I/O: Output only
Method Details  
At the beginning of run, the Conservation Pool Storage Fraction is populated as follows: For each date (row) and each level, n, (column), the equation to compute the fraction:
Note:  The Conservation Pool Storage Fraction is limited to be always between 0 and 1 (0% to 100%).
At the end of each dispatch method, the Operating Level series slot is computed by looking up the pool elevation and date on the Operating Level Table.
Next, Conservation Pool Full Storage is calculated as follows.
The Conservation Pool Storage is computed as follows:
If the Operating Level is greater than the Top of the Conservation Pool,
else if the Operating Level is less than the Bottom of the Conservation Pool,
else
* Conservation and Flood Pools
This method allows the user to specify that there is a conservation and a flood pool for this reservoir.
Slots Specific to This Method
This method is an extension of the Conservation Pool method, and selecting this method causes all the slots for Conservation Pool to become available, along with the following.
 Top of Flood Pool
Type: ScalarSlot
Units: No Units
Description: Operating level (as defined in Operating Level Table) corresponding to the top of flood pool.
Information:  
I/O: Required input
 Flood Pool Storage
Type: Series
Units: Volume
Description: This is the computed volume of water in the flood pool.
Information: This value is always non-negative.
I/O: Output only
 Flood Pool Full Storage
Type: Series
Units: Volume
Description: This is the possible volume of water that could be stored in the Flood pool. It is computed as the Storage at the top of the flood pool minus the storage at the top of the conservation pool.
Information:  
 Flood Pool Storage Fraction
Type: Periodic Slot
Units: Fraction
Description: The values in the periodic slot represent the percentage of the flood pool storage at each level (column) in the Operating Level Table.
Information: It has identical dimension including dates and levels as the Operating Level Table. This table will be populated at beginning of run. The Operating Level Table will be its “source” slot.
I/O: Output only
Method Details  
At the beginning of run, the Conservation Pool Storage Fraction is populated as described above. Then, the Flood Pool Storage Fraction is populated as follows: For each date (row) and each level, n, (column), the equation to compute the fraction is:
Note:  The Flood Pool Storage Fraction is limited to be always greater than 0. But, it can be larger than 1 (100%). For levels above the flood pool, the percentage will be greater than 100%.
At the end of each dispatch method, the Operating Level series slot is computed by looking up the pool elevation and date on the Operating Level Table. Next, all slots associated with the Conservation Pool are computed and set as described above. Then, Flood Pool Full Storage is calculated as follows:
The Flood Pool Storage is computed as follows:
If the Operating Level is less than the Top of the Conservation Pool,
else
Note:  The Flood Pool Storage may be larger than the Flood Pool Full Storage. This indicates the reservoir is above the flood pool and is surcharging.
Revised: 08/04/2020