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Coastal management strategies
Coastal management aims to protect homes, businesses and the environment from erosion and flooding. Strategies have to take into account the following:
- Flooding and erosion of the coastline will have social, economic, and environmental impacts.
- The amount of money available is limited, so not everywhere can be protected.
- Choosing which places can be defended and how is based on cost-benefit analysis. Consequently, the money available is usually used to protect larger settlements and critical industrial sites.
To achieve this, the following options are available.
Hard and soft engineering
Hard engineering involves building artificial structures that aim to prevent erosion. The structures are usually at the base of a cliff or on the beach. They effectively prevent erosion in the desired area, but they are expensive and have a significant environmental impact due to the use of concrete and other artificial materials. In addition, reducing erosion in one area of the coastline may exacerbate erosion elsewhere. Therefore, their only impact is to change where erosion is occurring.
Soft engineering aims to work with and complement the physical environment by using natural coastal defence methods. They manage but do not necessarily prevent erosion. Soft engineering uses ecological principles and practices, which have less of a negative impact on the natural environment. As a result, it is less expensive to implement and maintain and creates more long-term and sustainable solutions than hard engineering projects.
The table below shows the common types of hard engineering.
Hard engineering options | |||
---|---|---|---|
Type | Definition | Advantages | Disadvantages |
Sea wall | Large walls constructed from concrete, steel, or stone are located along the shoreline of a beach. | Protects cliffs from upland erosion and is a barrier to flooding. | Waves can erode the wall defeating its purpose and is expensive to implement and maintain. |
Groyne | Wooden fence-like barriers are built at right angles at the beach. | Prevents longshore drift, flooding, and erosion. Allows beaches to build up. | Can create erosion further down the coast. Unattractive and expensive. |
Gabion | Bundles or rocks in metal mesh located at cliff bases. | Reduces the impact of waves. | Inexpensive hard engineering structure, but not very effective or attractive. |
Revetment | Slanted structures made from concrete, wood or rocks along a cliff. | Prevents cliff erosion as it absorbs wave energy. | Expensive to implement. Can create a strong backwash. |
Coastal/Tidal barrage | Partly submerged dam-like structures that control the tidal flow. | Create a more consistent water level that can be used for hydroelectricity. | Has a substantial impact on the environment. Expensive to implement and maintain. |
Rock armour (rip rap) | Large boulders or rocks piled up on a beach in front of a cliff or sea wall. | It absorbs the energy of waves and helps build up beaches. | Expensive to implement and maintain. |
Cliff stabilisation | Metal bars are inserted in cliffs to reinforce them. | Improves the strength of the cliff and prevents rocks from falling | Can create a metal mess |
Table 1 |
And here are some common types of soft engineering.
Type | Definition | Advantages | Disadvantages |
Beach nourishment | The beach is made wider by using sand and shingle. | Increases the distance a wave has to travel, thus slowing it down and preventing erosion. | Sand and shingle must be sourced from somewhere else, usually by dredging. Requires maintenance and can be expensive. |
Managed retreat | Certain areas of the coast are allowed to erode and flood naturally. | Natural eroded material encourages the development of beaches and salt marshes. Low cost. | Required to compensate people who lose buildings and farmland. |
Dune stabilisation | Planting dead trees in the sand to stabilise dunes. | Widens the beach/dune, therefore, slowing down waves and preventing erosion. | Trees need to be sourced and require maintenance. |
Dune regeneration | Creating new sand dunes or restoring existing ones. | Dunes act as a barrier and absorb wave energy reducing erosion and protecting against flooding. | Dunes are a barrier to beach access and creating new dunes results in a land loss. |
Afforestation | Stabilising dunes by planting trees. | This minimises sand drift and erosion. | Planting non-native species can affect the nutrients in the soil. |
Mangrove planting | Planting mangroves along the shore. | Mangrove roots keep soil in place, which dissipates wave energy and prevents erosion. | Mangroves are non-native to some areas and can become invasive. |
Coral reef preservation and enhancement | Protecting existing reefs. | Coral reefs reduce wave energy. | Man-made reefs can cause contamination. |
In general
Hard engineering can be expensive, and it disrupts the natural process.
Soft engineering is a more sustainable management strategy than hard engineering because it has a lower environmental impact and economic cost.
Governance approaches
Approximately two-thirds of the world’s population live within a few kilometres of the coast. However, they increasingly face a threat from rising global sea levels, although there is uncertainty about the scale and timing of the rise. There is an increased frequency of storms and the possibility of increased erosion and flooding. Given its importance, careful consideration needs to be given to managing the coastline to ensure that its resources are utilised wisely while preserving its natural beauty and processes.
Therefore, coastal management must be sustainable. In other words, the strategies should not cause too much damage to the environment, people’s homes and livelihood and shouldn’t cost too much.
To achieve this, the following are taken into consideration:
Cost-benefit analysis (CBA)
This takes place before any coastal management takes place. The anticipated cost of the coastal management plan is compared to the expected benefits of a scheme. These may include the value of land, homes and businesses that will be protected. Cost and benefits may be tangible (monetary value) or intangible (other effects such as visual impact). For a CBA, the expected benefits must outweigh the costs for a project to go ahead.
Shoreline Management Plans (SMPs)
An SMP has been created for each sediment cell in the UK to help with coastline management.
There are 11 sediment cells in England and Wales. These do not exist in Scotland and Northern Ireland, where the devolved governments and local authorities are jointly responsible for coastal protection.
Each SMP identifies all the natural and human activities that occur within the coastline area of each sediment cell. The sediment cells are closed for the purposes of management, although there will be some exchanges between the different sediment cells.
Four ways of managing coastlines are:
Sustainable Integrated Approach (SIA)
As the negative impacts of many shoreline management plans (SMP) have become evident, sustainable integrated approaches are becoming more widely used. These are holistic strategies; it is recognised that all the different sections of the coastline are interlinked and function together as a whole. Smaller areas are not considered separately, unlike traditional methods.
Managing the coast sustainably includes:
- Managing natural resources like fish, water, farmland to ensure long term productivity.
- New employment for people who face unemployment because of protection measures.
- Educating communities about the need to adapt and protect the coastline for future generations.
- Monitoring coastal changes and then using adaptation or mitigation to respond to the observed differences.
- Ensure consideration is given to everybody when changes are proposed and then adopted.
Integrated Coastal Zone Management (ICZM)
This is another method of sustainable coastline management. This is where all coastline elements (land, water, people, and the economy) are managed with one integrated strategy. Its aims are:
- Protect the coastal zone in a relatively natural state whilst allowing people to use it and develop it in different ways.
- Local, regional, and national levels of authority must work and manage coasts together.
- It recognises the importance of the coast for people’s livelihoods.
- That coastal management must be sustainable, whereby economic development is essential but is not prioritised over the protection of the coastal environment.
- It must involve all stakeholders, plan for the long term, and work with the natural processes and not against them.
- It recognises that sediment eroded in one location may form a protective beach elsewhere. Therefore a decision to protect one coastal community may not outweigh the disadvantages of exposing another community to increased erosion.
- It is a dynamic strategy where decisions are re-evaluated if the environment or demands on the area change.
Coastal management involves decisions that will affect peoples lives. These effects can be positive or negative. However, it inevitably means that it will divide stakeholders into two groups.
- Winners – people who have gained from the decision which have been made either economically (property saved) or environmentally (habitats conserved), or socially (communities).
- Losers – people who have not had their property saved or see the coastline being “concreted over” through defensive measures, which they see as a negative environmental impact.
Fortunately, the UK has frameworks in place for dealing with coastal management. Sadly, the most vulnerable people and coastlines are the losers in less developed countries as they have no way of claiming compensation or there is no coastal management approach in place.
In Phuket in Thailand, erosion has caused the loss of beaches. Local villages use ad hoc methods to try and stop the power of the waves, and hoteliers have resorted to sandbagging their resort area.
Coastal Management - Key takeaways
- Management of the coastline is necessary to protect them from coastal erosion, flooding, and rising sea levels.
- Coastal management must be sustainable; any strategy adopted must not cause unnecessary damage to the environment, people’s homes and livelihood and should not cost too much.
- Coastline management strategies involve hard or soft engineering.
- Before any management strategy is adopted, a Cost-Benefit analysis is done.
- Governance approaches include Shoreline Management Plans (SMPs), Sustainable Integrated Approaches (SIA) and Integrated Coastal Zone Management (ICZM).
References
- Fig. 2: Groynes at Mundesley in Norfolk, UK. This is a hard engineering method in coastal management (https://en.wikipedia.org/wiki/File:Groyne_at_Mundesley,_Norfolk.JPG) by MichaelMaggs (https://commons.wikimedia.org/wiki/User:MichaelMaggs) Licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/deed.en)
- Fig. 3: Gabion reinforced with earth in Sveti Rok, Croatia (https://en.wikipedia.org/wiki/File:SvetiRok.jpg) by Antonio Canfora (no profile) Licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/deed.en)
- Fig. 4: Wooden revetment (https://en.wikipedia.org/wiki/File:Sturdy_revetments_-_geograph.org.uk_-_1119250.jpg) by Evelyn Simak (https://www.geograph.org.uk/profile/14840) Licensed by CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0/deed.en)
- Fig. 5: Tidal barrage in France (https://en.wikipedia.org/wiki/File:Rance_tidal_power_plant.JPG) by User:Dani 7C3 (https://commons.wikimedia.org/wiki/User:Dani_7C3) Licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/deed.en)
- Fig.8: Beach grass to stabilise dunes at beaches (https://en.wikipedia.org/wiki/File:Helmgras_kijkduin_februari_2005.JPG) by User:Ellywa (https://commons.wikimedia.org/wiki/User:Ellywa) Licensd by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/deed.en)
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Frequently Asked Questions about Coastal Management
How effective is coastal management?
Coastal management is effective in that whichever method is chosen as a management approach protects homes and businesses from being damaged and even destroyed by coastal erosion or flooding. However, they may inhibit longshore drift and speed up the erosion process elsewhere.
Why does the coastline need to be managed?
The coastline needs to be managed to protect against increasing coastal erosion, flooding and sea-level changes
What are the different types of coastal management?
There are two types of coastal management, hard engineering, which involves building structures to protect the coast. Or soft engineering, which works with nature, using natural materials, or allowing nature to take back areas.
How could a coastline be managed?
A coastline could be managed by hard engineering approaches such as a sea wall made of concrete with steel reinforcement and deep pile foundations. It can have a stepped or “bullnose” profile. It acts as a physical barrier against erosion and flooding. Modern sea walls are designed to dissipate wave energy.
What are some coastal management strategies?
Beach nourishment – artificially replacing the sediment on the beach.
Dune regeneration – creating new sand dunes or restoring existing ones. Beach stabilisation – planting dead trees in the sand to stabilise it.
Groyne – Building wooden fence-like barriers at right angles to the beach.
Coastal barrage – partly submerging dam-like structures that control the tidal flow.
Riprap – Large rock boulders piled on the beach in front of the cliff or sea wall.
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