As best I can tell, this L shaped device requires a small (maybe one foot by one foot), continuous concrete footing set flush with the bottom. It is basically comprised of two sheets of plywood to a unit; supposedly two men can erect 100 meters of this water tight wall in one hour after the footing is initially built. It can be taken apart and used again and again. A recent article in the Democrat Gazette said it is being used as a replacement for sandbags to control flooding in North Dakota. The literature did not mention what the two green striped poles hanging over the wet side of the barrier were for. Looks like a slalom gate to me.
This might have an application as a way to temporarily create some concentrated flow, like for a surfing contest. Brain gears spinning. Summer dam release flow concentration; set up wall, hold surfing event, take down; no permanent floodplain water surface increase; FEMA happy; paddlers happy; tourists happy; local businesses happy; no permanent detriment to upstream movement of aquatic species; AGFC and FWS happy; no permanent change to natural flow regime; river purists happy (no they will gripe). Spinnnnnnn gears spinnnnnn.
Captain Aleve, alias Mike Coogan