Coastal Defense: Soft Stabilization

Strategies Stabilization techniques
Hard Stabilization Soft Stabilization

Soft Stabilization techniques include the following:
(i) Beach nourishment
(ii) Sand dune stabilization
(iii) Beach face dewatering

(i) Beach nourishment:

A beach is the perfect defence against wave action and, if a beach is poor, one option may be to undertake beach nourishment.

Beach nourishment basically involves adding large quantities of material to a beach in order to build it up. beach nourishment: pictureThe material added will need to be very similar to the material naturally found on the beach and will probably come from remote sources.

Offshore dredging can provide a good source of suitable material for beach nourishment schemes or alternatively the sediment can be obtained from land based quarries.

Beach management structures may also be necessary to ensure the extra material remains on the beach, and even so some will probably be lost through the natural movement of coastal sediments.

This may mean further nourishment is required in the future to keep the beaches at the desired level. This involves importing alien sand off the beach and piling it on top of the existing sand. The imported sand must be of a similar quality to the existing beach material so it can integrate with the natural processes occurring there, without causing any adverse effects.

Beach nourishment can be used alongside the groyne schemes. The scheme requires constant maintenance: 1 to 10 year life before first major recharge. It is a better way of managing the coast rather than using the Hard Construction Techniques. However, the procedure is costly and only temporary.

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(ii) Sand dune stabilization:

Sand dune stabilization is a coastal management technique sand stabilization: schematic diagramfor preventing erosion.

Sand dunes trap sand and beach material washed and blown up, the rate of erosion is slowed and an effective flood barrier is created. Footpaths will also have to be introduced to stop trampling.

Sand dunes stabilisation is economical, environmentally friendly, does not disrupt the coastline further on, creates natural habitats for animals and plants and is not regarded as unattractive.

However, for successful dunes to be placed it must be thoroughly researched beforehand and will take a long time to establish.

Sand dunes may be stabilized through the planting of vegetation. Vegetation encourages dune growth by trapping and stabilising blown sand.

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(iii) Beach face dewatering:

Beach drainage or beach face dewatering lowers the water table locally beneath the beach face. This causes accretion of sand above the drainage system.

Beach face dewatering basically involves continuously pumping water away from the beach face.

The system is based on the idea that, when the water table under the beach face dewatering: schematic diagrambeach is lower than under the ocean, sand accretion is enhanced.

As each wave rushes up the beach, water from the wave easily drains through the dry beach, leaving part of its suspended sand load on the beach. Less water drains back into the ocean taking less sand with it.

How beach face dewatering works:

When the water table under the beach is lowered, water from the wave easily drains through the dry beach, leaving part of the suspended sand load on the beach. Thus, the beach accretes

A specially designed drainage system is installed under the beach, with pumps removing groundwater from under the beach. When considering such systems, operation and maintenance costs must be taken into account. The pumps should run continuously.

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References:
from standard technical literature & various websites including:
http://www.wisegeek.com, http://www.japantimes.co.jp,
http://www.egr.msu.edu, http://content.answers.com,
http://dcm2.enr.state.nc.us, http://www.northnorfolk.org,
http://www.english-nature.org.uk, http://www.havant.gov.uk,
http://www.coastalplanning.net, http://www.herveybay.qld.gov.au,
http://www.unesco.org, http://www.globalsecurity.org,
http://jrscience.wcp.muohio.edu & http://www.wikipedia.org

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