Ineffective areas?

[tjsuchoski]

I am trying to define a portion of the flood plain and overbank area that will not receive any flow, i.e. a section low section behind a levee. I have tried defining these areas as being ineffective flow areas. However, when I analyze this configuration, the HEC-RAS simulation in the program calculates the flows fine, but when I ask for the results to be displayed, the ws elevation is shown across the entire area.
Is there a way to model this without removing the cross-section data behind the levee?

[tjsuchoski]

I have determined that the ws should be shown in the ineffective areas as this will be flooded if it were say a culvert. However, I'm trying to model the flow in a channel with a levee. So how does one do this and how can the flow be limited to occurring only within the channel area and not on the back side of the levee? Also, how can it be prevented from showing up in a cross-section results?
Additionally, when I ask for the flood plain mapping to be done, the ws is also shown as extending into the low areas behind the levee. Any way to prevent this?

[Chris Maeder]

Note that you should define levee stations if you do not want HEC-RAS to account for the flow area beyond the cross section levees. Note, however, that for the floodplain mapping to restrict the flow within the leveed area, the levee cannot have any "breaks" in them to allow water to leak out. Otherwise, RiverCAD will detect where these levees are leaking, and will extend the floodplain mapping further beyond the levees.

[Wiener_H]

Hi,
I drew 2 polylines representing a left and a right levee along one reach (out of 14 reaches in the total project).
But after defining the levees and trying to run a simulation I got an error message saying the left levee is higher then the right one...
Also, is it possible the computer uses these levees for the other reaches? Or is it just for the current reach I'm working on?
Thanks

[Debajit Basu Ray]

Hi,

This error message comes when you select wrong polyline to assign levees. You should select left polyline for left levee line and right polyline for right levee line looking downstream. You might have selected levee lines looking upstream.

Thank you,

Debajit