Dear Merle :

Note that when you define roughness coefficients at a cross-section, you need to define it for the left overbank, channel, and right overbank (unless you are using multiple horizontal roughness coefficients). RMS / RiverCAD will then propagate the roughness on upstream until you define it again at another cross-section. The roughness values will only be displayed at the cross-sections that you have defined them at, although the software will continue to propagate the defined values on upstream. However, don't make the mistake of defining only a left overbank
roughness and not the others. Otherwise, the HEC-2 and HEC-RAS software will assume that you have defined a roughness of 0.0 for the channel and right overbanks.

If you have any additional questions or need any further information, please contact me again.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com