HW stage at SA/2D Area Connection

[Anonymous]

Hello everybody.
I have a doubt regarding the way HEC-RAS calculates the HW-Stage at SA/2D Area Connection in case of 2D simulations.

In my case I have a dam (inside a 2D area) with 5 gates whose opening/closing is “Based on upstream WS”. By checking the Stage-HW values reported into the “Stage and Flow Hydrographs” table I noticed that gates opening was wrong. In particular they opened when the stage HW written in table was lower than the reference value specified in the boundary contidions rules.
I noticed drawing a profile line parallel to the upstream side of the dam, that the WSE varies (0.8m of difference between left and right) and I found out that the HW stage value reported in table was more or less corresponding to the lower values of 2D cells along dam profile. Thus I imagine that the gate opening/closing is based on the WSE recorded at 2D cells directly connected to each single gate.
So here it comes my question. Is my analysis correct? If yes, why does the table reports the minimum value of WSE upstream of the dam and not for example the mean value (maybe it would be better to report the minimum, the medium and the maximum).

Thanks

[Lonnie A]

Your analysis is correct. It’ll use the cell that correspondss to the station of the gate for control. They had to pick something to pull the data from and easiest was to use the lowest cell for reporting which usually would be the one you’d want when you have a culvert.

[Anonymous]

Thank you for your explaination. Glad to know that my analysis was correct.
Best wishes

[Author]

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