Note that the floodplain mapping should not run out of memory unless you have an extremely large AutoCAD drawing and your computer has limited memory.
You can also break your existing reach into separate reaches. In that way, you should be able to get around this problem.
If you have any additional questions or need any further information, please contact me directly.
Sincerely,
Chris E. Maeder, M.S., P.E.
Senior Technical Engineer
chris.maeder@bossintl.com