Dam Break Analysis at Culvert Locations

[traggatmot]

Hello,

I am performing a dam break analysis at culverts located at stream road intersections, assuming they have become clogged and are acting like dams, until they are breached. Accordingly, I do not put a culvert in the model, but instead am putting in a Weir as a SA/2D Area connection, and setup a breach plan for the structure. Here is my question:

Can I simply have the weir structure setup without having to remove the road material? Or do I have to carve out the road, with the area removed from the DEM equal to the width/length of the weir / dam I wish to model, before putting in the weir?

In other words, does putting in a SA/2D Area connection override the cell values that are present in the mesh that were generated form the DEM? Or does it not, and I have to alter the DEM to remove the road and road fill to the extent of my weir?

Thanks,
Tom

[Anonymous]

There are two separate issues, the cells and the faces.

The flow from one cell to the next is controlled at the faces. The weir you enter overrides the faces along the length of the weir. The faces are adjusted to represent the breach.

Adding a weir does not change the cell volume tables. This isn’t usually an issue, unless the cells are very small.

For your situation, having the road already in the terrain is probably better as the cell volume table will be more accurate. The breach will lower the adjacent cell. I would post a picture, but I’m not sure how to do that. So as long as you don’t have more than two cells on the road embankment, I think you should be ok.

I would leave the road in and try it and see if the results look reasonable.

[Author]

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