HEC-RAS 1D/2D _ Different Water Surface Elevation between 1D and 2D

[AliR]

We are running a HEC-RAS 1D / 2D model for modeling the floodplain.
When drawings profile line for a specific cross-section in the floodplain we see different water surface elevations between 1D and 2D.

We have tried adjusting the weir coefficient and also the weir submergence decay exponent without any success to in removing the drop between the 1D and 2D.

Any input would be greatly appreciated.

[Anonymous]

On the weir editor, make sure the weir flow reference is set to water surface not energy. If it is energy that might explain the difference.

You might also try setting the lateral structure to 2D equation domain and see if that gives better results

[cameron]

Make sure that the 1D/2D iteration option is turned on as that will force the wse to try and match. You may also want to adjust the weir coefficient to get a better match or just use the 2D equation for the weir which may be the best option, but watch out for the lateral structure bug with bridges.

(https://www.hec.usace.army.mil/software/hec-ras/known_issues.aspx)

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