Can anyone here direct me to a resource on swales and how to safely implement them into a landscape? I've done a bit of research and know that the spacing between swales is contingent on the amount of rainfall per year. I also think that the overflow channel might mitigate the chance of a land slide or a mass wasting event as geologists put it. Mark Shepherd has referenced an urban swale that some folks in Wisconsin built without doing their research. It broke and flooded, causing tons of damage to the surrounding buildings. Does anybody here have tales of swales breaking and how to fix that potential problem? I've heard folks ask Ben Falk about this potential problem on his landscape but never have I heard a solid answer from him.
Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
posted 4 years ago
When my swales or check-dams have broken, it's been during thunderstorm caused flash flood events. And at that time there is already so much water, mud, boulders, and vegetation flowing that a little bit more is inperceptible. The materials flow downstream until they get hung-up on some obstruction or other. That might be a few feet, or a few miles. The flow of water tends to be concentrated on the point of failure, so ravine formation is typical just below the point of failure. Stilling pools or rip-rap just below spillways really helps with structural integrity during flash flows.