Chris,

You have answered a couple other questions regarding RMS for our floodplain project. I initially provided Manning's coefficients (0.035) only at the downstream section (assuming subcritical flow) for the left, center and right banks, and analyzed the floodplain. Later, I added a different coefficient (0.028) for the right overbank for a portion of the floodplain that lies in a golf course. This involved 19 cross sections in the middle of the project (out of a total of 57 cross sections). Again, I ran the analysis and calculated the water surface. However, when I revised this coefficient in the golf course to 0.03, the water surface elevation process ended in a fatal error, and I had to change the cross sections back to 0.028.

My questions are:

1. Are Manning's coefficients entered for only some cross sections read by RMS (and HEC-RAS) instead of the default coefficients entered only at the downstream cross section?

2. Is it impossible to later change this coefficient?

3. Do have any idea why this coefficient does not display on the first 6 cross sections (from downstream), but does on the remainder? The first section to display is at the end of a row.

Thanks for your time,

Merle Miller
Cape Environmental Management, Inc.
10010 San Pedro Ave., Suite 345
San Antonio, TX 78216
(210) 377-2008