Rain Barrel LID Fluxes in SWMM 5.0.021

 

Subject:  Rain Barrel LID Fluxes in SWMM 5.0.021

 

The fluxes are limited in a Rain Barrel Low Impact Development (LID) control in SWMM 5.  The fluxes only include (Figure 1 and Figure 2):

 

1.      Total Inflow,

2.      Surface Outflow,

3.      Drain Outflow and

4.      Final Storage

 

The fluxes are also listed in the LID Performance Summary Table in the output text file.

 

  ***********************

  LID Performance Summary

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                                   Total      Evap     Infil   Surface    Drain      Init.     Final     Pcnt.

                                  Inflow      Loss      Loss   Outflow   Outflow   Storage   Storage     Error

  Subcatchment      LID Control       in        in        in        in        in        in        in

  -----------------------------------------------------------------------------------------------------------

  S1                RainBarrels    110.95      0.00      0.00     62.95     28.15      0.00     23.11    -2.94

 

Figure 1. Flux Pathways for a Rain Barrel LID


 

Rain Barrel LID Drain Outflow in SWMM 5.0.021

 

Subject:  Rain Barrel LID Drain Outflow in SWMM 5.0.021

 

 The drain outflow in a Rain Barrel LID is defined by the user defined drain coefficient and drain exponent and the simulation storage depth  The storage outflow does not occur until it has been dry for at least the drain delay time in hours.

Figure 1.  Storage Outflow or Drain Outflow for a Rain Barrel LID

 

Figure 2. You can see the effect of the Drain Delay in the output file for LID Simulation.

 

 

What is Hours Above Full Normal Flow in SWMM 5?

Subject:  What is Hours Above Full Normal Flow in SWMM 5?

 

The Conduit Surcharge Summary Table in the Report text file or Status Report lists a column of results called “Hours above Full Normal Flow”.  This is the number of hours the flow in the link was above the REFERENCE full flow as calculated by Manning’s equation.  The flow in the link can be above full flow even if the link is not a full depth if the head difference across the link is high enough.  The head difference is the water surface elevation at the upstream end of the link minus the water surface elevation at the downstream end of the link.  The capacity or d/D of the link varies from 0 to 1 with 1 being a full pipe or link.

Figure 1.  Hours above Normal Flow in SWMM 5 Links

 

Figure 2. Flow versus Full Flow in SWMM 5