Beaver Dam Weir Coefficient

[Scott Miller]

The Weir Equations in HEC-RAS post in The RAS Solution has a usable diagram for effective coefficient. It takes the relative width and relative depth of a weir into account, but what about roughness? How should characteristics of a beaver dam or debris berm be taken into account (if modeled)?

[Luis Partida]

If it is 1D, I would increase the roughness coefficient of the US and DS cross sections. If it is 2D I would also adjust the associated cells roughness coefficient assuming they were small enough to not impact adjacent cells.

Another option could be to model the weir as a cross section with Lids. In this instance you could correlate an exact cross section with a weir and associated roughness coefficient. You could also add a minor loss coefficient to the model in the Table of the geometry data editor.

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