Bentley StormCAD CONNECT Edition Help

New Return Event from Chicago Storm Data

To add a new return event from Chicago Storm Data, follow these steps:
  1. Open Storm Data from the Storm Data button on the Components Tab.
  2. Create a new Time-Intensity group.
  3. Click the new button above the list on the right and click "New Return Event from Chicago Storm Data…"

The dialog consists of the following input:

  • General Input
    • Label: Enter a distinguishing label for the storm event.
    • Return Event: Enter the frequency of the event.
  • Chicago Storm Input
    • Data Format: Choices are Equation (default) and table.
    • Equation
      • Intensity Unit: The unit that the equation input parameters are based on. The calculation of the intensities is in this unit. The results are converted to inches per hour for storage and then converted to the current display units.
      • Coefficient A, Constant B and Exponent C: The parameters for the Chicago storm equation.
      • The duration, time interval and peak time ratio are required and used to generate the hyetograph based on the equation data.
      • The Sherman I-D Equation is used to calculate the hyetograph.

    • Table
      • Enter in the tabular data as an I-D curve. The data is used to generate a hyetograph.
      • The difference between each time value in the I-D curve must be the same.
      • A minimum of three points is required.
      • The alternating blocks method is used to calculate the hyetograph using I-D table data. See <link> for additional details.
      • Import button
        • The import drop-down button has two options:
          • From File: You can import from a txt, csv or InRoads IDF file.
          • Import from IDF Table: Select a user defined IDF Table to import the data from. Only user defined IDF Tables can be selected.
        • If the selected IDF table does not have a constant time interval, you are prompted to enter one.

        • Quadratic interpolation is used to calculate the intensities for the times started at the first time of the IDF Table to the last time at the specified interval to "normalize" the IDF curve.
  • IDF Curve
    • The graph will show the intermediate IDF curve that is calculated before creating the hyetograph.
    • Valid data must be entered for the curve to appear.
    • If the equation data form is used, a red error icon will appear to the right of the field if the value is invalid.
  • Generating the Hyetograph
    1. After entering in the data in the dialog, it is validated.
    2. When all data is valid, a new hyetograph is generated based on the input.
    3. Hyetograph from Equation Data
    4. Hyetograph from Table Data
Parent topic: Storm Data Dialog Box