"When these plants are abundant, they are generally associated with soil disturbance, lack of soil cover or overgrazing."
We're planning to put in brush dams this winter. The scary thing about brush dams is you can have a "blow-out" if the first flood is a really big one, bringing all the brush downstream where you don't necessarily want it - in our case probably right in the middle of our driveway. I'm hoping we'll get a few smaller floods first so the brush dams can get nice and packed in and collect some soil and - I hope - grow some plants.
We weren't building swales at the time, just moving dirt. We were working on a hillside that is Milton silty clay loam (Mtd3) and it was compacted enough that the claw was needed to break up the ground. Each bucket full was dropped to the side; later we moved the earth elsewhere. Unless the soil was very moist there really wasn't a problem with it sticking in the bucket.
I don't think the swails will prevent flooding, but they would help retain water on your land after a rain or a flood.
Here's an article about building swales with a bulldozer: http://permaculture.org.au/2009/11/30/keyline-swal...f-lawtondarren-doherty-hybrid/
Sounds to me like a berm that keeps the excessive water off of your property might solve the flooding issue.