Baymouth bar
A baymouth bar is a depositional feature as a result of longshore drift. It is a spit that completely closes access to a bay, thus sealing it off from the main body of water.
These bars usually consist of accumulated gravel and sand carried by the current of longshore drift and deposited at a less turbulent part of the current. Thus, they most commonly occur across artificial bay and river entrances due to the loss of kinetic energy in the current after wave refraction.
Sand Bypass Systems
In most cases, a Sand Bypass System is built to prevent these bars forming across the entrance of human-made seaways, eliminating the danger to commercial and recreational boats passing through.
The world's first permanent Sand Bypass System was built on the Gold Coast in Queensland, Australia.