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Objects and Methods : Level Power Reservoir : User Methods : Rating Curves Modification
Rating Curves Modification
This category is dependent on having Flat Top Surcharge method selected in the Surcharge Release category. Methods are used to optionally modify the Rating Curves table.
* None
This is the default method, no modification to the Rating Curves is made.
* Specify Rating Curves using Elevation
When the Specify Rating Curves using Elevation method is selected the following slot is added.
Slots Specific to This Method
 Rating Curves using Elevation
Type: Table Slot
Units: Elevation vs Flow vs Flow
Description: This table represents the Rating Curves Table with Elevation as the independent variable instead of Storage as shown on the Rating Curves table. Thus, The table relates Elevation, Induces Surcharge, and Free Flow Rating Curve.
Information: Specified only
I/O: Not linkable
Method Details 
When this method is selected, at the beginning of the run, the reservoir uses the following process to generate the Rating Curves based on the Rating Curves using Elevation slot.
1. Copy all the data in the Rating Curves using Elevation table to the Rating Curves table. This resizes and/or rebuilds the table, as necessary.
2. For each row in the Rating Curves using Elevation table, the Elevation is looked up on the Elevation Volume Table to determine the Storage.
3. Storage is written to the Rating Curves table. The Induced Surcharge Curve and Free Flow Rating values were already copied from the Rating Curves using Elevation table.
4. The Rating Curves table is marked as “has Source Slot”. This makes the slot read-only, with cross hatching over the value.
Note:  These values are automatically generated based on Reservoir.Rating Curves using Elevation.
Within the Flat Top Surcharge method, the original Rating Curves (storage based) tables are used for all computations.
Revised: 08/02/2021