Monday, September 12, 2016

New Events Editor In EPA SWMM 5.1.011 and InfoSWMM Non Steady Period Dialog

The Events Editor in SWMM 5 (Figure 2) is activated when the Events sub-category of simulation Options is selected for editing from the Project Browser.   InfoSWMM has the same feature but it called Non Steady Period (Figure 1)

It is used to limit the periods of time in which a full unsteady hydraulic analysis of the drainage network is performed. For times outside of these periods, the hydraulic state of the network stays the same as it was at the end of the previous hydraulic event.  Although hydraulic calculations are restricted to these pre-defined event periods, a full accounting of the system's hydrology is still computed over the entire simulation duration. During inter-event periods any inflows to the network, from runoff, groundwater flow, dry weather flow, etc., are ignored. The purpose of only computing hydraulics for particular time periods is to speed up long-term continuous simulations where one knows in advance which periods of time (such as representative or critical storm events) are of most interest.

The new tab for Non Steady State periods in InfoSWMM and H2OMap SWMM allows you to use the  Skip steady State option for selected  time periods.

If selected and the change in lateral inflow or node volume or node depth is higher that the defined tolerance for any single node in the collection system, then hydraulic routing will be conducted, otherwise the steady state condition will be assumed.  (See Improved Dry Weather Computation Efficiency for more information.)

Skip Steady State Period - Select to skip steady state period and use the tolerances below or leave blank to use internal default tolerances. (Note: Internal default tolerance: Lateral Inflow = 0.00001 cfs, Node Depth = 0.00001 ft, Node Volume = 0.01 ft3.)

Lateral Inflow Tolerance - minimum change in lateral inflow per simulation timestep for hydraulic routing to be performed.

Figure 1 - InfoSWMM Non Steady Periods

Figure 2 - Event Editor in EPA SWMM 5.1.011

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