Hydraulic performance of multibarrel culvert under inlet control

[Calvin Leung]

I am conducting the hydraulic performance analysis for both multibarrel and single-barrel culvert systems under inlet control. In current practice, single-barrel culvert design procedures have been applied to multibarrel culverts by treating each of the barrels in the multibarrel culvert as a single culvert and summing the individual flow capacities(superposition). However in the real situation, multibarrel culvert does not have the same hydraulic performance as a single-barrel culvert because the amount of inlet flow contraction associated with each culvert in a multibarrel culvert is less than the flow contractions experienced by a single-barrel culvert. Therefore, the method of superposition does not apply to multibarrel culvert. I want to know if HEC-RAS utilizes the method of superposition or have the ability of modelling the real situation considering the effect of contraction when analyzing a multibarrel culvert.

Thank you so much!!!

[user]

One way I can think of is adjusting the ineffective flow area before and after the multiple culverts.

[Anonymous]

So HEC-RAS evaluates the flow capacities of a multibarrel culvert by treating each of the barrels as a single culvert and summing up their flow capacities?

[user]

Yes. If you want the individual flow for culverts of different sizes , just specify more culvert groups . At the end , you would get the summation of their flows.

[Author]

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