Reporting weighted Runoff Coefficient for catchments that use the Multiple Subareas option

  Product(s): StormCAD, CivilStorm, SewerGEMS
  Version(s): 10.03.04.53 and earlier
  Area: Output and Reporting

Problem

When using the "Multiple Subareas" option for the "Area Defined By" field in the properties of a catchment, why does the "Runoff Coefficient (Rational)" show as blank / yellow in Flextables? How can I report the weighted / composite Rational C for a catchment that uses multiple subareas?

Solution

Currently a weighted (composite) Rational Runoff Coefficient field is not available. This is planned to be addressed in a future version (reference # 932400) 

In the meantime, you can set up a formula-derived User Data Extension (UDX) as a workaround:

1) Go to Tools > User Data Extensions

2) Right click on Catchment > Add Field, name it something like "Rational C (Weighted)"

3) On the right side, populate:

- Name (this can be similar to the label)

- Category (where you want it to appear in the properties grid list)

- Field order index (where it should appear in that section compared to the other fields - a high number indicates lower in the list)

- Field Description (informational message to appear at the bottom of the properties when clicking the field)

- Alternative (which alternative to store the data - the User Data Extensions alternative should be fine since this is a computed field)

4) Select "Real (Formula)" as the Data Type, click in the "Formula" field and click the ellipsis button (...)

5) In the formula editor, scroll down the list to "Catchment CA" and double click to add to the formula. Click the divide button to add the divide symbol or type '/', then scroll up to and double click the field "Area (Unified)". Make sure the units match (such as Acres)

6) Click OK, then select the storage units:

- Dimension - No Units

- Storage Unit - (blank)

- Numeric Formatter - Coefficient


7) Click OK to create the User Data extension. Review the properties grid or flextables. be sure to compute the model first, as the Catchment CA field is a computed field. The model will need to be re-computed after making a change, in order for this to update.

Note: you can share this user data extension with other users (for use in other models) using the export/import options at the top of the User Data Extensions manager.

Example Model

You can download an example model with this set up using the below link. Note that you must have version 08.11.05.58 or greater in order to open this model.

Sample_2_weightedRunoffCoefficient.zip

See Also

Using Modelbuilder to import or export catchment Subarea data

Creating Formula-based User Data Extensions

Creating Custom Calculated Results with Formula User Data Extensions

Recommended
Related