Coastal Protection Structures
Coastal Protection structures are constructed principally to protect the coastal line. They are useful for changing current and sand movements but also to redirect rivers and streams. These structures are built to:
- Slow down or prevent coastal erosion
- Increase access or mooring sites (marinas, bridges, causeways and boat ramps)
- Support coastal sub-division (power poles and storm water pipes)
Types of Coastal Protection Structures
Various structures are employed for the coastal protection. Some of the basic structures are described in the following:
This type of coastal protection is built along the shoreline to prevent it from the detrimental influence of ocean waves and flooding which are caused by the storms. The construction of these structures include materials like rubble mound, granite masonry, or reinforced concrete. Seawalls are classified into the following depending on the arrangement:
- Curved face seawall
- Stepped face seawall
- Rubble Mound Seawall
Construction of these type of structures include materials like cement , timber, steel .These may not be strong enough to be exposed to substantially strong wave actions. Their main purpose is to retain earth but while designing these structures, the designer should consider the scouring at the base of the structure. Another purpose of these structures is to protect the upland area against damage from wave action. Two major types of Bulkheads are gravity structures and anchored sheet pile walls.
These structures reduce the erosion effects till the shoreline by changing the offshore current and wave patterns Groins are built by concrete, stone, steel or timber. These structures are categorized depending on the length, height and permeability. Moreover, groins are usually constructed vertically to the shoreline and they can either be impermeable or permeable.
Jetties are also normally built of materials such as concrete, steel, stone, timber, and sometimes asphalt is also used in its construction as a binder. These structures are located at river estuary or harbor entrances and are constructed into deeper water to oppose the formation of sandbars and limit the currents.
Breakwaters are classified into 3 major types which are namely:
- Rubble mound
These protect the coastal area, anchorage and harbor from the wave actions but also create safe environment for mooring and to operate ships.