1D No-Rise analysis problems

[RAS_]

Hello,

I'm working on a 1D HEC-RAS no rise analysis for a site, after construction (long story). Development included changes in the overbank at one XS, mostly cut. Pink is post-project on the graphic below.

The floodway run doesn't have a rise, as one would expect here. The 100-year run has a significantly decreased WSE for two XS upstream (0.1', 0.2') but slight increased WSE (0.04') at the third upstream XS.

In my mind, this is a "no rise" but the model needs a few changes to prove this.

Adding (interpolating) XS upstream seems to help but not sure how this is received on the FEMA end.

Thoughts?


w

 

[Ekenny_G]

No interpolated XS allowed in FEMA model. However, the No-Rise you mentioned is very close. You can play around with adjusting bank stations either up or down to eliminate the small increase.

 

[gbam]

Maybe evaluate your Corrected Effective model for ineffective flow areas and assess the proposed condition. We are doing that exact thing for one of our projects. Not sure if it applies, but worth a check.