We have a serious beaver problem also. I have the plans for that drainage system you mentioned and it seems quite workable. With this system the beaver are allowed to damage property.
For land owners like us that have a beautiful aspen forest by the lake it is just sickening to go out one morning and see several 30 foot tall aspens laying on the ground.
The best way to save the trees is to kill off the beaver by shooting, trapping or other means. Yes they do come back, so the problem is perpetual.
A neighbor who has the “they were here first” attitude lets them run wild. What was once a half acre slough is now a 25 acre lake which killed thousands of trees and made it so the typical wildlife such as deer, turkey, raccoon etc etc etc have less habitat for their survival.
The dams are made of tree limbs, mud and rock. Over the years they gradually build to 10 - 15 feet high which means just an awful lot of water behind them. When the tree limbs and other organics start to rot the dam weakens and busts flooding downstream wiping out more trees, crops and property.
I shoot the bastards on sight!!!
I have 3 acres of land that is now usable for pasture land that was once lake or swamp and all it cost me was three 22lr rounds. I shoot them on site.
If you just tried to reason with the beavers* violence wouldn’t be necessary...