Coastr

Coastal management

Coastal management (also coastal protection or sea defence) is defence against flooding and erosion by the sea. There are many different ways to protect the coast but I have specifically chosen four.

Groynes

Groynes are artificial structures often made of concrete and/or rock barriers or walls perpendicular to the sea. It is used to interrupt water flow and limit long shore drift. In the ocean, groynes create beaches, or avoid having them washed away by long shore drift. In a river, groynes prevent erosion and ice-jamming. Ocean groynes are generally perpendicular to the shore, extending from the upper shore or beach into the water. All of a groyne may be under water. In this case it is called a submerged groyne. The areas between groups of groynes are called groyne fields. A groyne creates and maintains a wide area of beach or sediment on its updrift side, and reduces erosion on the other. It is a barrier to stop sediment transport in the direction of the longshore drift. This causes a build-up, which is often accompanied by accelerated erosion of the downdrift beach, which receives little or no sand from longshore drift. Groynes do not add additional material to a beach, but merely retain some of the existing sediment on the updrift side of the groynes.

Seawall

Seawall is a hard and strong coastal defence constructed on the inland part of a coast to reduce the effects of strong waves. Seawalls may be constructed from a variety of materials, most commonly reinforced concrete, boulders, steel and gabions. A downside of a seawall is its expensive cost to build. Today, seawalls cost between £2000 to £5000 per metre. Modern concrete seawalls tend to be curved to reflect the wave energy back out to sea. Poor designs require constant maintenance as waves erode the base of the seawall. A range of seawall types are made in relation to wave energy, resembling cliff and beach profiles. Vertical seawalls are built in particularly exposed...