A storm data is a single rainfall curve that represents one rainfall event for a given recurrence interval. The rainfall curve can be represented in one of three ways.

• Intensity
• Incremental
• Cumulative

Once the storm data is created it can either be used locally at a catchment, or it can be used globally by selecting Components > Storm Data > Global Storm Events. This will apply the storm data to the current scenario. This storm data will then be applied to all catchments during analysis that do not have localized rainfall. Because Drainage and Utilities dynamically routes flow through the system, it requires a complete storm hyetograph (i.e. a table with rainfall vs. time). There are many methods including actual historical storms and synthetic storms. These can be entered as cumulative precipitation or incremental precipitation.

For background on rainfall data, see the Modeling Rainfall chapter in Stormwater Conveyance Modeling and Design or the Wet weather flow chapter in Wastewater Collection System Modeling and Design. Both books are published by and available from Bentley Institute Press.

A storm data can be created one of two ways, both from within the Storm Data dialog box:

• You can manually create a storm data by selecting Cumulative, Incremental, Intensity, or IDF Storm Data when selecting New to create a new curve in the Storm Data dialog.
• You can construct a storm data from a dimensionless rainfall curve stored in the associated Dimensionless Rainfall Curve engineering library. To do so select From Dimensionless Curve when selecting New to create a new storm data in the Storm Data dialog box.

To add a storm data:

1. Select Components > Storm Data.
2. You can define a local storm data for a specific catchment in the Rainfall section of the catchment’s Property Editor. Set Use Local Rainfall? to True, then select the ellipses (<...>) from the Local Storm Data submenu.
3. In the Storm Data dialog box, click the New button, then select the type of storm data you want to create from the submenu (Cumulative, Incremental, Intensity, IDF Storm Data, or From Dimensionless Curve).
4. Define Cumulative, Incremental, Intensity, and IDF storm data on the Data tab by performing the following steps:
5. For Cumulative, Incremental, and Intensity storm data, type the Start Time, Increment, and End Time in the Time Settings dialog box, then click OK. The Time Settings dialog box appears as soon as you select one of these storm data from the New submenu. For Cumulative, Incremental, Intensity, and IDF storm data, type the number of years in the Return Event field. For Cumulative, Incremental, and Intensity storm data, enter Depth or Intensity data values in the table. The Time values are automatically filled in based on the time settings you defined for the storm data. To edit the time settings, click the Edit button on the Data tab. For an IDF Storm Data, enter Time and Intensity data values into the table. Pressing Tab or Enter after typing a value creates a new row in the table.
6. To define a From Dimensionless Curve storm data, perform these steps:
7. Select From Dimensionless Curve from the New submenu. The Engineering Libraries dialog box appears, showing the Dimensionless Rainfall Curve Library. Click the plus sign next to the library to expand it, select the dimensionless rainfall curve you want to use, then click Select. The Rainfall Curve Import Settings dialog box appears. Select the Storm Data Data Type (Intensity or Depth), the Storm Data Depth Type (Incremental or Cumulative), then type values for Depth and Duration. Click OK to close the Rainfall Curve Import Settings dialog box. The storm data appears in the Storm Data dialog box. Double-click the event to edit the import settings.
8. In a Cumulative Dimensionless Depth rainfall curve, time is in hours and depth is dimensionless. In a Cumulative Dimensionless rainfall curve, both time and depth are dimensionless.
9. You can save your new storm data in Drainage and Utilities’ Engineering Libraries for future use. To do this, perform these steps:
10. Select the storm data you want to save. Click the Synchronization Options button, then select Export to Library. The Engineering Libraries dialog box appears. Use the plus and minus signs to expand and collapse the list of available libraries, then select the library into which you want to export your new storm data. Click Close.
11. Perform the following optional steps:
12. To delete an event, select the event label then click Delete.
13. To rename an event, select the event label you want to rename, click Rename, then type the new name for the event.
14. To view a report on an event, select the event label for which you want a report then click Report.
15. To graph the rainfall for an event, select the event label for which you want a graph then click Graph.
16. Click Close to close the Storm Data dialog box.

To add a storm data in the Engineering Libraries:

1. Select Components > Catalog > Engineering Libraries to display the Engineering Libraries dialog box.
2. Click the plus sign next to the Storm Data Library to expand the list of items (categories and folders) included in that library. You can add new items to a category or a folder, add new folders to categories, and add new categories to libraries.
3. Right-click a category or folder in the Storm Data Library and select New Item. The new item appears at the bottom of the list of items in the selected category or folder.
4. Define the new storm data in the Editor pane on the right as described in the following steps:
5. Select the type of storm data from the Storm Data Type submenu (Time vs. Depth, Time vs. Intensity, or Rational Method IDF Curve).For Time vs. Depth or Time vs. Intensity storm data, type the start time, increment, and end time in the appropriate fields. For a Time vs. Depth storm data, select the depth type from the Depth Type submenu (Incremental or Cumulative).For a Time vs. Depth storm data, click the Ellipses (...) button next to the Depths field, then enter Time vs. Depth data in the Storm Data dialog box. Click OK to close the Storm Data dialog box when you are done. For a Time vs. Intensity storm data, click the Ellipses (...) button next to the Intensities field, then enter Time vs. Intensity data in the Storm Data dialog box. Click OK to close the Storm Data dialog box when you are done. For a Rational Method IDF Curve storm data, click the Ellipses (...) button next to the IDF Curve field, then enter data values in the Rational Method IDF Curve dialog box. Click OK to close the Ration Method IDF Curve dialog box when you are done.
6. To create a Dimensionless Rainfall Curve in the Engineering Libraries, perform these steps:
7. Right-click the category or folder in the Dimensionless Rainfall Curves library in which you want to store your new dimensionless rainfall curve, then select New Item. The new item appears at the bottom of the list of items contained in the category or folder. Select the new item, then define the curve in the Editor pane. Select the Dimensionless Time Type (Time or Dimensionless Time), then type values for the Start Time, Increment, and End Time. Click the Ellipses (...) button next to the Dimensionless Depth field. The Rainfall Curve Dictionary dialog box appears. Time or Synthetic Time values are automatically inserted into the data table based on the start time, increment, and end times you entered. Type values for Depth, then click OK. Click Close to close the Engineering Libraries.
8. Click Close. Your storm data is now part of the Engineering Libraries and can be re-used any time.