Subject:  RDII Initial Abstraction in SWMM 5

The initial abstraction in each of the three components of RDII in SWMM 5 are updated at each time step.  The initialabstraction (ia) is:

ia = iaMax - iaUsed

based on the maximum amount of ia, the ia used (iaUsed), the recovery rate (iaRecov) and the month and class of RDII.  You can enter a value for iaMax, iaInit and iaRecov for each month.

The iaUsed at the beginning of the simulation is set equal to iaInit

and if there is no rainfall

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