Weir flow

[JUNGJJ]

I have a situation where a bridge is also acting like a Broad Crested weir. The bridge ghas an opening of riughly 34' wide and a deck width of 9'. First off I do not beleieve the water should be pooling this high as I have observed close to 100 yr storm and the outcome is not what is being generated by HEc-Ras. The other thing that is trowing me for a loop is that from onside of the bridge to the other the water depth going over the bridge decreases 2.5'. Any ideas of what exactly might bee my goof in modeling?

may be the critical depth is hydraulic control, and the critical depth
is 2.5' lower than the normal depth of the other side.

Hope this might help
AbbAs Fawaz P.E.
AFawaz@pbsj.com