Would anyone be able to direct me to the right tool or tools that will take a POLYLINE (or polyline raster) overlain with a DEM raster, and obtain a 5 feet HIGHER area than the height of the floodplain boundary? Many places say to use the Euclidean Allocation tool, but the documentation for that is lacking -in my opinion. It does not perform the function I'm seeking. Thank you.
This is probably oversimplistic, but can't you make contours of your DEM and extract the contour line you're interested in? It seems to me that your floodplain polyline should all fall at one elevation, but this may not be the case...
