Subject: The Pump flow is based on the lookup table you enter for the pump (Figure 1). At each iteration during each time step of the solution SWMM 5 will look up the flow for thepump based on the current control variable across the pump. The control variable for the pump can be one of four variables:
1. The volume of the upstream wet well,
2. The depth of water at the upstream node or inlet node without interpolation between data points,
3. The downstream water surface elevation across the pump minus the upstream water surface elevation, and
4. The depth of water at the upstream node or inlet node with interpolation between data points.
The pump summary table in the rpt file will tell you how often the pump was used, the maximum flow, the average flow, the total volume of the pump, the power usage and the percent of the time off the entered pump curve. You can also plot the pump flow versus the inlet depth to see how often the pump was off the pump curve (Figure 2).
Figure 1: Plot of Head and Flow for Pump PUMP1@82309e-15009e over time along with the input and output table for the pump.
Figure 2: Plot of Head versus Flow for Pump PUMP1@82309e-15009e