[Jesse]

Hi Jarvus – thank you for your time and your reply.

After I posted, I thought maybe the 2D mesh was the culprit – I’m using 40 foot cell sizes, so there was 5 cells between the 2D Connection Dam and the bottom of the reservoir. I removed points from the mesh until the cells at the breach location stretched to the bottom of the reservoir. I’m just now reviewing the results, but my preliminary review suggests this method has worked.

I will also incorporate your solution of making the breach covered by only one cell.

Again, I appreciate your time!

[Jesse]

I’ve read numerous posts from you that suggest modeling a sequential dam breach suing only a single 2D Flow Area. Using your posts as a guide, I’ve been able to to do; I’m using a SA for the upstream reservoir, but am modeling the downstream reservoir as part of the single 2D flow area (and using an internal boundary condition to fill the reservoir to max level before the incoming upstream breach flow). This is a sunny-day failure and no inflow from tributaries is being modeled.

However, I’m having a problem whereby the second (downstream) reservoir is not completely emptying even though the 2D Connection breach parameters have a bottom elevation that is the same as the reservoir bottom elevation. There still is about 10 feet of water in the reservoir when the simulation ends. It’s as if the dam breach bottom only affects the inline structure width (that is, the dam crest width of 20 feet), and isn’t cutting the terrain for the dam back to the reservoir bottom (3:1 inside slope); e.g. the dam crest might be getting to the specified breach bottom elevation, but that elevation isn’t being “cut back” into the reservoir.

This problem doesn’t exist when I use a simple SA – the SA is populated with elevation-capacity relationship, and the breach bottom elevation properly drains the entire reservoir.

Any insight you can provide would be greatly appreciated. Thanks!

[Author]

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