Hazen Williams and Force Mains in SWMM 5

A few tips for using Hazen Williams and Force Mains in SWMM 5.   A key fact is to remember ONLY one flow in the middle of the link is computed in SWMM 5 so you may have to add Break nodes, use a smaller time step and use a flap gate depending on how often your pumps turn on.  If you do not have numerical problems with the time step you should get exactly the same head loss as you do in steady state Hazen Williams calculators when you use InfoSWMM, H2OMap SWMM and SWMM 5.

Figure 1.  Larger Tip Image 
Figure 2.  SWMM 5 compares well to the Hazen Williams Head loss calculators



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