SWMM5, InfoSWMM

Subject: How to make Multiple Storm Events in InfoSWMM and How to Use them in the Scenario Manager

Step 1. Make a new Time Series to hold the data points for your new Rainfall Time Series in the Operation Tab of the Attribute Browser.

Step 2. Populate the Rainfall Distribution with a SCS Type II Hyetograph with a 1 inch rainfall total

Step 3. Now Clone the created Rainfall Distribution and make 10, 25, 50 and 100 year storm events each with 1 inches of rainfall in a cumulative distribution.

Step 4. Now use the Block Edit command and convert each of the newly created hyetographs to 4, 7, 10, 15 and 20 inch cumulative rainfall totals from the original 1 inch rainfall total (for example).

Step 5. Now create a Raingage for each of the newly created hyetograph time series using the DB Editor under the Raingage Table in Hydrologic Data

Step 6. Link the Time Series to the new Raingages and define the type (cumulative), units (inches) and hyetograph interval (15 minutes)

Step 7. Make 4 New Scenarios for the different return period hyetographs, the Base Scenario will use the 5 year or 4 inch SCS II rainfall.

Step 8. Use the DataSet Manager and make 4 new Subcatchment DB Tables in which each Subcatchment Set uses a different return period hyetograph.

Step 9. Run the Batch Simulator for all 5 scenarios including the Base Scenario.

Step 10. You can use the Output Report Manager to see the Rainfall for all of the Batch Runs to check if the proper rainfall was used for each Scenario Simulation.