Building a DWF Pattern in InfoSWMM and InfoSWMM SA

Building a DWF Pattern

Time Patterns allow external Dry Weather Flow (DWF) to vary in a periodic fashion. They consist of a set of adjustment factors applied as multipliers to a baseline DWF flow rate or pollutant concentration. The different types of time patterns include:

  • Monthly – one multiplier for each month of the year
  • Daily – one multiplier for each day of the week
  • Hourly – one multiplier for each hour from 12 AM to 11 PM
  • Weekend – hourly multipliers for weekend days

Each time pattern must have a unique alpha-numeric identifier (up to 32 characters with no embedded spaces or special characters) and an optional (recommended) description. There is no limit on the number of patterns that can be created. Each dry weather inflow (either flow or quality) can have up to four patterns associated with it, one for each type listed above. In this tutorial, you will build an hourly DWF pattern. At any timestep, the loading at a junction is the average value multiplied by the current pattern multiplier.

You will enter 24 multipliers for an average day loading pattern andInfoSWMM InfoSWMM SA will apply each multiplier for a 1-hour period during the simulation.

1. Select the OPERATION tab from the InfoSWM InfoSWMM SA Browser, click once on TIME PATTERN and then right-click and select the “New” command.

2. You are then prompted to enter a new ID and description for the pattern. Enter “DWF, Dry Weather Flow” in the PATTERN ID field and choose the “OK” button.

3. The PATTERN dialog box now appears on the screen. From the drop-down combo-box, select “3:Hourly” for PATTERN TYPE. Then, you may enter the following 24 pattern multipliers (representing a residential neighborhood). The factor is limited to 24 hourly multiplicative patterns.

Hour or Factor 1 Hour or Factor 2 Hour or Factor 3 Hour or Factor 4 Hour or Factor 5 Hour or Factor 6
0.65 0.65 0.65 0.75 0.90 1.2
Hour or Factor 7 Hour or Factor 8 Hour or Factor 9 Hour or Factor 10 Hour or Factor 11 Hour or Factor 12
1.45 1.8 1.5 1.1 1.0 1.1
Hour or Factor 13 Hour or Factor 14 Hour or Factor 15 Hour or Factor 16 Hour or Factor 17 Hour or Factor 18
1.0 0.9 0.85 1.05 1.2 1.1
Hour or Factor 19 Hour or Factor 20 Hour or Factor 21 Hour or Factor 22 Hour or Factor 23 Hour or Factor 24
1.05 1.0 0.90 0.85 0.75 0.60

4. To define the twenty-four multipliers for Time Pattern DWF, perform the following:

· Enter the pattern factors as defined above and press the ENTER key to apply the change.

· As you add the multipliers the graph will be automatically updated on the dialog box.

· Click on the “Save” button at the top of the dialog box to apply the factors to the Time Pattern ID DWF. The following picture illustrates how the pattern should appear on the dialog box.

5. Choose the “OK” button to close the PATTERN dialog box. Pattern ID DWF now contains 24 multipliers and is ready for use.

Refer to the Working With Data Objects à Time Patterns topic in the on-line InfoSWMM InfoSWMM SA Help for more information on patterns and their use in InfoSWMM InfoSWMM SA .


Now that a Time Pattern of loading multipliers has been defined, the pattern can be assigned to the nodes. This could be done using several ways including assigning for one node at a time using the ATTRIBUTE Browser, using the DB EDITOR, and using GROUP EDITING. In this section of the tutorial, you will use the GROUP EDITING ON SELECTION feature.

1. Click on the InfoSWMM icon or from the InfoSWMM H2OMap SWMM InfoSWMM SA CONTROL CENTER toolbar and then choose the GROUP EDITING ON SELECTION command from the EDIT menu or alternately click once on the GROUP EDITING ON SELECTION icon from the InfoSWMM InfoSWMM SA EDIT NETWORK toolbar. The cursor changes in to a red rectangle.

2. Select all network elements in the collection system by dragging the mouse so that the selection region covers all data elements. The selected components will change color (the default color is yellow). Right mouse click and select “Enter”. The GROUP EDITING dialog box will now appear.

3. Choose the INFLOW tab on the GROUP EDITING dialog box, and then click on the DRY WEATHER tab. Type “0.05” in the AVERAGE VALUE field, and select the “DWF, Dry Weather Flow” pattern for the TIME PATTERN field.

4. Click on the “Apply” button to accept the changes, and close the dialog box by clicking on the “Close” button. Now all nodes in the “Tutorial” project are assigned the “DWF” pattern.

Refer to the Working with Data Objects à Inflow topic in the InfoSWMM H2OMap SWMM InfoSWMM SA on-line help for more information on dry weather flow.

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