Offset Elevations in SWMM 5

Introduction

 A new button command in SWMM 5 will allow you to calculate the link offsets in terms of elevation instead of the default method of offset depths.  This ability duplicates the SWMM 4 capability of using either depths or elevations for the link offsets. 

If command button Offsets (Figure 1) is used then all of the link offsets will be calculated from the node invert elevation and the user input offset depth (see Figure 2). 

                                   Figure 1.  Offsets Command Button.

                               Figure 2.  Inlet and Outlet Offsets will be in terms of Elevation not Depth.
 

Figure 3.  Turn off the Checkbox for Link Offsets in Depths to use the new Offset Elevations in the Tab SWMM 5 Options=>Advanced Dialog.

The checkbox "Link Offsets in Depths" (Figure 3) allows the engine to use either:

• Depths as Offsets (the default), or 
• Elevations as Offsets

The engine will recalcuate the link Offsets as depths in the engine if the checkbox "Link Offsets in Depths" if turned OFF.  The internal offsets are shown in the XSection Summary Table (Figure 4).

   ********************
  * Xsection Summary *
  ********************
  Conduit          Shape               Yfull     Wmax    Afull    Qfull          Z1          Z2  Barrels  Flow Limit
  ----------------------------------------------------------------------------
  8040             CIRCULAR             4.00    12.57     1.00     4.00        0.00        0.00     1       73.65
  8060             CIRCULAR             4.00    12.57     1.00     4.00        0.00        2.20     1       53.27
  8100             CIRCULAR             4.50    15.90     1.13     4.50        0.00        0.00     1       78.06
 

Figure 4.  Turn off the Checkbox for Link Offsets in Depths to use the new Offset Elevations.

SWMM 4 to SWMM 5 Conversion Notes

If the parameter  JELEV > 0 on the BB line of SWMM 4 then the translator will automatically  use the SWMM 4 Link offset elevations in SWMM 5; the Checkbox ""Link Offsets in Depths" will be turned OFF; and the command button Offsets does not have to be checked in the SWMM 5 GUI.

This is how the JELEV parameter was used in SWMM 4:

*      JELEV  :  Input elevations instead of depth for variables ZP1
*                and ZP2 on data line C1 and elsewhere in the data inputs
*                = 0  Enter conduit depth offset (ZP values), default.
*                = 1  Enter absolute elevation of conduit offset ZP1
*                     and ZP2 only.
*                = 2  Enter elevations in place of depths for conduit ZPs and
*                     for initial water elevations on D1 line.
*                = 3  Enter elevations in place of depths for conduit ZPs,
*                     initial water elevations of D1 lines, and surface area/
*                     elevation data in place of surface area/depth data on
*                     E2 lines
*                = 4  Enter elevations in place of depths throughout program
*                     including pipe ZPs, junction initial depth YO,
*                     surface area/elevation on E2 lines, orifice ZP,
*                     variable orfice control depth, weir YCREST and YTOP,
*                     and pump station control depths.