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The Coastal

Erosion Problem

 

Coastlines all around the world

are eroding and the combination of severe storms and subsequent littoral drift is stripping sand, shingle and soil from beaches and coastal cliffs, first carrying it offshore and then down-coast. It is nevertheless recognised that wide natural beaches are the best protection against wave attack. Their shallow slope and long run-out width encourages dissipation of wave energy, hence protecting cliffs and dunes from damage. However, many beaches remain subject to storms, followed by littoral drift moving beach material along the coast. This narrows the affected beach and reduces the resistance of adjacent dunes and cliffs to storm damage.

 

Conventional coastal defences such as sea walls, groynes and breakwaters can often exacerbate erosion caused by scouring at their base and vortex generation at the ends. For a more detailed explanation, click on Conventional Sea Defences. To appreciate the scale of this worldwide problem, download World Market for Coastal Protection. It should be noted that coastal erosion persists independently of the threats of climate change or sea-level rise, though these threats might make it worse. A lasting solution to coastal erosion could open the door to land reclamation, and a positive defence against sea-level rise.

A Lasting Solution                                                Erosion at Birling Gap – Photo: John Allen

 

Naturally stable beaches exist all around the world. They are crescent-shaped bays with rocky headlands at each end and they do not suffer from erosion. Storms will remove material from the beach but it does not escape from the bay and is returned to rebuild the beach. This has led to the idea of artificial stable bays, first proposed around 1965 and first created in Singapore in 1972. The concept is to install a row of islands offshore that naturally collect drifting sediment between them and the shore. This creates a string of stable bays between the islands, which become headlands. The first artificial stable bay scheme used short breakwaters as headlands and an initial charge of sand to supplement the drift. It has survived for 40 years in a benign location.

 

The only problem with this idea, as explained in Stable Bay Technology, is the vulnerability of the breakwaters themselves to being undermined by the same processes that undermine other conventional structures. The headlands need to be as stable as the beaches. The solution is to replace the breakwaters with circular islands. For a full explanation of how this works, click on Shoreform Stable Bays. For a summary, download A Unique Solution to Coastal Erosion. No alternative option offers its permanence, cost-effectiveness or simplicity of operation.

The Global Problem

      With the possible exception of polar regions, all worldwide coastal zones are affected by erosion, even those considered to be stable on the adjoining European map.  The number and extent of the "managed retreat" coastal reaches on the UK map show the degree to which coastal recession has been accepted as inevitable.

The Shoreform solution offers real

stability as an alternative scenario.

The airport at Rio de Janeiro located in the downtown area of the city (Image: Claudio Freitas Neves).

Storm damage on the western coast of France during winter storm Xynthia (Source Roberts, 2010a).

The UK Coastal Flooding

Image credit:

European Environment Agency (EEA) is an agency of the European Union

 

2015

Revision 180216

The use of circular artificial islands as sediment accretion devices is protected

by UK and International patents awarded or pending to Shoreform Limited.

Every effort has been made to acknowledge relevant copyright holders. In the event of any omission please contact Shoreform Ltd.