HEC-RAS discharge under bridge - Left overbank

Enter the portion of the total left overbank discharge that flows under the structure from HEC-RAS output in cfs (cms).

When the overbank sections are relatively small, and where the channel is likely to move laterally within the structure, consider analyzing the flow as being all channel flow without overbank sections.

For some cases such as (1) bends; (2) large overtopping flows over approach roadways; or combinations of (1) and (2), the flow distribution under the bridge becomes complex and HEC-RAS may not be able to properly model these conditions. Under these conditions, user can override the discharge under the bridge to account for such complex flow patterns. Several examples of such problems and suggested solutions are presented in the ABSCOUR Users Manual, Chapter 11, Appendix A. This approach is generally recommended for sensitivity analyses rather than for final scour evaluations.