AB Dam

I cannot answer this question specifically, because I’m not precisely familiar with those damns, the river that they dam, the terrain that they’re built in, or how far they are, and what position their floodplain is from civilization.

But as a general rule –

If a dam is instantly taken away (however it’s done), the reservoir of water behind the dam will be instantly released. The potential energy of the stored water (which is a lot, bigger and bigger as the reservoir gets bigger, especially as it gets taller) is quickly converted into kinetic energy in the form of water rushing down river. This will be very powerful, and very fast, and so it will gouge out the river channel, making it deeper and wider (this won’t just be done by water, but the force of the water will pick up large rocks and carry them along, which will help gouge out the river bottom). Depending on the size of that dam, the effects could be catastrophic to the immediate environment, wiping out fish, wiping out animals and plants near the banks of the river.

Downstream, (again, this depends on the size of the first dam) the force of the water could be enough to break the second dam, which would just add more force, and more energy to the water running downstream, making the effects even bigger (the potential to break the second dam lies in the size and shape of the second damn’s reservoir – if there is a long reservoir behind the damn, that will help to better “absorb” the force, which could save the second dam).

If that second dam breaks, then it will gouge out the riverbed even worse, as I already stated, and just like the second dam, could potentially destroy the third dam. It could theoretically be an enormous “domino effect” which would more than likely end up effecting human cities downstream.

There is a link below to explain about the destruction cause by the failure of the Teton Dam. It will give you lots of interesting information.