| Applies To | |||
| Product(s): | PondPack | ||
| Version(s): | V8i, CONNECT Edition | ||
| Area: | Layout and Data Input | ||
| Original Author: | Mark Pachlhofer, Bentley Technical Support Group |
Problem
What is the purpose of the "Store Elevation-Flow-Tailwater tables?" calculation option?
How can I speed up calculation time by storing outlet EQT tables for ICPM outlets?
Solution
When set to "true", the "Store Elevation-Flow-Tailwater tables?" calculation option will cause the elevation-flow-tailwater tables of all Interconnected Pond Modeling (ICPM) composite outlet structure to be computed and stored, when the model is computed. This will only occur for such composite outlet structures that have the "Store elevation-flow-tailwater table?" option set to "Yes". (see screenshot below)
When EQT tables are stored as input using this option, you can select them in the outlet link properties to use for subsequent calculations. This speeds up performance of model calculation since the model will then use the stored values instead of having to re-compute the outlet rating table.
You can also choose "false" for the calculation option, then manually compute and store individual outlet EQT tables using the steps below (and then select them in the outlet link properties).
NOTE: In version 10 (circa 2008 and earlier) a check box was available in the pond route properties, to "Use EQT table?". This option allowed the user to compute the EQTW table for the individual outlet structure first and then have Pondpack re-use that table during the full network calculations, instead of re-computing it. This feature saves on calculation time and is still possible in V8i, using these steps:
If choosing to store the EQT tables, consider using a smaller tailwater and headwater increment of 0.1 ft for example (set in the composite outlet structure properties). With this, the results will be more accurate as opposed to getting interpolated results between elevation increments.
Steps to use Stored EQT
1) Go to Components > Composite Outlet Structures and create your composite outlet structure. A tailwater type of "Interconnected ponds" must be selected to use EQTW curves.
2) Click the name of your composite outlet structure and choose "Yes" for the "Store Elevation-Flow-Tailwater table?" property.
3) Select "Create new EQTW series" for the "Elevation-Flow-Tailwater" field.
4) Compute the EQTW rating curve by clicking the green compute arrow at the top. After calculation, the EQTW table will be stored in the Elevation-Flow-Tailwater manager.
5) Close the Composite Outlet Structure manager and look at the properties of your pond outlet link.
6) Select "No" for the "Has control structure?" field, "Yes" for "Use Elevation-Flow-Tailwater Table?" and select the EQTW table entry from the "Elevation-Flow-Tailwater Table" field. Now when you compute your model, it will use the stored EQTW table instead of recalculating it.