method is the wall doesn't corrode or compost over time requiring less management. These are deemed soft defenses as opposed to hard defenses that include solid concrete retaining walls that cost a fortune and are unsightly to local people. It would seem local residents, environmental agencies, local councils and budget managers are more open to a natural flow system that mimics nature and holds large volumes of water back for later draining. The biggest motivator is this method costs a fraction of the hard defenses that professional government agencies have been promoting. References Dams by type Flood barriers