One of the limitations of using Dry Weather Flow (DWF) in SWMM 5 and InfoSWMM is that the same DWF pattern is repeated every 24 hours for either a Weekday or Weekend. This pattern can be changed by multiplying by the Daily and/or Monthly pattern but the same core hourly pattern stays the same. There is an alternative, however, and the alternative is to use a time series over a period of days or weeks that matches either your monitored data or a weekly dry weather pattern.
Here is an example of how this is used. The base DWF pattern is over a 24 hour period (Figure 1). The two day result is copied from the InfoSWMM report manager and applied as a multiple day pattern in the time series editor (Figure 2). The Scenario Manager of InfoSWMM allows two runs: (1) DWF Pattern only and (2) DWF Pattern + Time Series for Two Days (Figure 3). The Output Report Manager of InfoSWMM shows that the Inflow Time Series + DWF is twice the DWF only (Figure 4). It shows that the the multiple day pattern is the same as the DWF pattern for two days.
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