Coastal Management

Coastal Management Broad Categories

May lead to land/coast being

lost.

May require a range of engineering

solutions.

Within a staged and

managed way.

Defences are built

out at sea.

CoastalManagement Broad Categories

DoNothing

ManagedRetreat

AdvanceThe Line

Allow natural processes.

Allow naturalProcesses.

Defendthe Coastline

HoldThe Line

Keep status quo.

Coastal Management Solutions

CoastalManagement Solutions

Beach Nourishment*

Sand Dune Stabilization

Rip Rap

Gabions

Groynes Sea walls

Breakwaters

Hard Engineering Solutions Soft Engineering Solutions

*Also referred to as “Beach Renourishment’.

Revetments

Tidal Barriers

Hard and Soft Engineering SolutionsHard Engineering Solutions

Soft Engineering Solutions

Hard engineering techniques are the MOST obvious of the Coastal Management Solutions and are the most obtrusive (stand out but not in a good way; an eye sore) on natural processes.

They INTERRUPT the natural processes or ‘TONE DOWN’ the energy of the waves to lower their IMPACT on the coastline.

Soft Engineering Solutions attempt to work with natural process to ENCOURAGE the coast’s NATURAL DEFENCES. These solutions have a lower IMPACT on the coast and how it would look without human interference.

At times, these solutions are not always appropriate due to the level of protection needed.

Hard Solutions: BreakwatersBreakwater

BREAKWATERS are usually large structures that are built to protect an area from particularly severe storms.BREAKWATERS are often built where there is a need to protect a PORT or HARBOUR but can also act to preserve beaches.BREAKWATERS differ from SEA WALLS as they are built in the water extending the NATURAL SHAPE of a HEADLAND.BREAKWATERS are expensive to construct and severely interrupt NATURAL PROCESSES.

Breakwaters

Hard Solutions: GabionsGabions

GABIONS are metal cages that a filled with stones.GABIONS can be used to STABILIZE the bases of CLIFFS that are particularly vulnerable to erosion.GABIONS are not expensive to install.GABIONS though DO NOT offer long term protection for the coastline.GABIONS offer an immediate response to erosion that has occurred or is at risk of occurring.GABIONS can pose a safety risk to those accessing the beach/coast.

Gabions

Hard Solutions: GroynesGroynes

A GROYNE is a wall made either of concrete, stone or strong wooden posts and planks.A GROYNE extends from the coastline to the level of low tide.GROYNES act as ‘sand traps’ interrupting the NATURAL MOVEMENT of SEDIMENT* (sediment collects on the side of the GROYNE where the sediment is moving from) by LONGSHORE DRIFT.A series of GROYNES are usually built along a coast to maintain a stretch of beach.GROYNES are often found in areas that are frequently used by humans.

Keep in mind: interrupting the movement of sediment can have impacts further along the coast, causing more erosion.

*SEDIMENT: sand and/or pebbles

Groynes

Hard Solutions: RevetmentsRevetments

REVETMENTS are concrete (or in some cases wooden) structures that are built along the base of a cliff. REVETMENTS are slanted and act as a barrier against waves; similar to a SEA WALL.REVETMENTS allow water and sediment to pass through an this gives the beach further protection.REVETMENTS absorb the energy of the waves, and help prevent the cliffs from being eroded.REVETMENTS can also have rippled surfaces that help dissipate the wave energy.REVETMENTS more often than not are successful at reducing coastal erosion.REVETMENTS are expensive to build but once built don’t require as much maintenance as a SEA WALL.

Revetments

Hard Solutions: Rip Rap (Rock Armouring)Rip Rap

RIP RAP is large boulders of rock that are placed along the edge of the coastline.Their role is to DISSIPATE the wave’s energy before it reaches the coastline with the end result the EROSIVE POWER of the wave is greatly decreased.

RIP RAP can make access to the beach/coastline difficult and interrupt the movement of sediment.RIP RAP is a cost effective way to manage the coast but it needs to be MAINTAINED especially if the supporting SEDIMENT underneath is removed by the waves.

NOTE: RIP RAP can also be used to build other structures such as sea walls, revetments (sloping structures) or groynes.

Rip Rap

Hard Solutions: Sea wallsSea walls

A SEA WALL is usually found in places where there are VIOLENT WAVES or where there is a risk of INUNDATION (flooding) of the coast.

There are different types of SEA WALL that are used.Older SEA WALLS tend to be flat and made out of STONE and CONCRETE.Modern SEA WALLS are often recurved and made from REINFORCED CONCRETE; the CURVED SURFACE rebound the wave back out to the sea which further dissipates the energy of the waves.

Sea walls

Hard Solutions: Tidal (Flood) BarriersTidal (Flood) Barriers

TIDAL BARRIERS are also known as FLOOD BARRIERS.TIDAL BARRIERS can be big, retractable walls built across estuaries (estuary: the tidal mouth of a large river, where the tide meets the stream) that can be used as a floodgate to prevent storm surges.TIDAL BARRIERS are very effective but they are also very expensive.

Tidal (Flood) Barriers

Soft Solutions: Beach (re)NourishmentBeach (re)Nourishment

BEACH (RE)NOURISHMENT is the supplying of additional SEDIMENT (sand and/or pebbles) to maintain SEDIMENT levels.

This is required when:The SEDIMENT INPUT through EROSION is LOWER thanthe OUTPUT via LONGSHORE DRIFT.Orto keep the beach maintained for TOURISM as a beach brings economic and social benefits.

In MAINTAINING a BEACH you are also offering a level of protection to the LAND behind it.

BEACH (RE)NOURISHMENT can be an expensive procedure due the volume of SEDIMENT required. BEACH (RE)NOURISHMENT offers limited protection for the coastline.BEACH (RE)NOURISHMENT needs to be maintained i.e. added at regular intervals preferably during the summer months.

Beach (Re)nourishme

nt

Soft Solutions: Sand Dune StabilizationSand Dune Stabilization

SAND DUNES offer DEFENCE against the power of the sea.SAND DUNES are also a vital habitat for a vast range of organisms.SAND DUNES occur naturally with large amounts of sediment input.SAND DUNES are naturally flexible; they will advance and retreat.If SAND DUNES are threatened then it may be necessary for some stabilization to be put into place.

This STABILIZATION can take many forms including:• Introducing soil fixing plants;• Offering additional support to existing species OR• Introducing small scale temporary defence in front of the SAND DUNE system.

SAND DUNES can quickly become unstable if threatened by EROSION from some other source or if the EROSION increases.

An example of this DESTABLIZATION: • HUMAN IMPACT: Simply, people walking on the SAND DUNES .

Sub aerial processes (weathering) can quickly blow away the top layer of soil and destroy vegetation. There is also the risk that the SAND DUNES can become TOO STABLE and no longer able to sustain or provide the range of habitats that make the SAND DUNES such an important habitat.

Sand dunes

Webography and Resources

Assembled by: A. Ballas

• Beach Breakwater

• Beach Gabions

• Beach Groynes

• Beach Renourishment

• Beach Revetments

• Beach Rip Rap

• Beach Sand Dunes

• Beach Sea Walls

• Geography Fieldwork