Please enable JavaScript.
Coggle requires JavaScript to display documents.
Coastal Erosion - Coggle Diagram
Coastal Erosion
Groins
Groins are long, wall-like structures that are constructed of stone rip rap, timber pilings, or steel sheet pilings. They are built along beaches that extend out into the ocean.
Groins act as barriers to longshore currents to control the movement of sand particles. The groin reduces the velocity of the longshore current on contact, causing the current to offload part of its sediment load on the up current side of the groin.
As a result, the adjacent beach builds up. Groins can be effective in preventing beach erosion, but it has their drawbacks.
As the longshore current passes the groin, it picks up additional sediment on the down current side of the structure which causes local erosion. Once one groin is installed, another is needed at the beach next door.
Jetties
Jetties are long structures constructed of stone, timber, steel, or concrete. They are built perpendicular to the shoreline and extend out into the ocean.
Their main function is to prevent sand from flowing into a ship channel, which would make the channel shallow over time. This is because shallow waters cause ships to run aground.
Jetties prevent storm waves and littoral drift from entering protected channels. They are also beneficial in preventing erosion. They can redistribute sand that builds up against the jetty along the beach.
Breakwaters
As the name implies, breakwaters are barriers to waves. They are built offshore to protect part of the shoreline, prevent erosion, and allow the beach to grow.
Thanks to the dissipation of wave energy, the material carried by longshore currents are deposited behind the breakwater to protect the shore. The downside of using this method is that the beach behind the breakwater often grows because it is not protected by the structure.
Note that the amount of deposition depends on two factors: the site characteristics and the design of the breakwater. The design of the breakwater may either be fixed or floating, depending on tidal range and water depth.
Seawalls
Although seawalls are effective in preventing erosion, they can only protect the coast where they are installed along.
Seawalls are an effective way to prevent beach erosion. These are structures that are built along the coastline to prevent waves from ever coming into contact with the sand/shore on the opposite side.
Vegetation
You can also use natural means to control erosion – one of which is by planting vegetation. Strategic planting of seagrass and other coastal plants helps prevent erosion.
This is because the roots of these plants help anchor the sand and ensure that it is not washed off in erosion. The downside to planting vegetation is that the beach may not be as functional as it once was, especially if its purpose is to entertain tourists.
Geotextile Installation
Geotextile wall is a popular and highly effective method of controlling erosion and improving soils over which roads, earth-retaining structures, embankments, and pipelines are built.
Geotextiles come in various types, including warp-knitted structure, open mesh woven geotextile, or nonwoven geotextile. The application will determine the type of geotextile wall that will be used.
Beach Nourishment
Beach nourishment is an artificial method of preventing beach erosion. It involves depositing sand on the beach to increase its width. This solution is temporary and does not require a structure; however, it is very expensive.