Hydraulic open channel modeling question HEC-RAS? SWMM?
Hydraulic open channel modeling question HEC-RAS? SWMM?
(OP)
I've got a tricky hydraulic open channel modeling problem (see the attached rough sketch). Essentially I have a large open channel that carries the 10- and 50-year storms, then a large swale parallel to the open channel to help convey the 100-year storm. However, the swale cannot extend past our property, so we are looking at putting in a very large pipe to move the water from the swale into the main channel. I have a HEC-RAS model from the county for the main channel, but I'm guessing HEC-RAS cannot model the dead-end swale + large culvert. Would SWMM work for this? Or do you have any other ideas for how I could model the water surface elevations? The overall goal of the project is to mitigate for a big mound of dirt next to the main channel. Widening / improving the channel is not really an option.
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RE: Hydraulic open channel modeling question HEC-RAS? SWMM?
Another option would be to calculate the losses at the pipe externally then hard code a starting condition.
RE: Hydraulic open channel modeling question HEC-RAS? SWMM?
The SWMM model would be useful in being sure that your swale doesn't overflow at more frequent storms, the HEC-RAS model would be useful at showing the effects of the floodplain.
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RE: Hydraulic open channel modeling question HEC-RAS? SWMM?
During a large storm, the pipe will be submerged and flow overtopping, so HEC-RAS seem ideal for the 100-year. You will just make the Large swale your "main channel" and flow path thru the culvert and then back to the main channel. Add cross sections upstream and downstream of the pipe culvert.