What is the best way to model a flood plain analysis in this scenario. The project I am working on is filling a channel in the flood plain. We are not allowed to raise the water over 1 foot. I saw in Chapter 6 about modeling. But not sure how to handle when I am actually filling the existing channel and creating a new one. Do I run the proposed and existing separately and just compare the values.
I would do exactly that. You typically want a calibration model with the existing conditions anyway. After you have that save the geometry file as something else and manually edit the cross sections. This alteration shouldn’t effect your delineation because all you really want is the WS elevation anyway.