They're doing that up on the Moors this year, building brush dams, heather, brambles and gorse mostly since they need an annual trim, into eroded run-off spills from the peat bogs. For exactly the same reasons, to stop erosion and raise the water-table in the peatland to stop it drying out. (and stop heathland fires as a result.)

I might just put in a few days of volunteer work if I'm able, although it's hard graft on the old back.