Coastal Erosion & Flooding Strategies (DP IB Geography)

Revision Note

Coastal Management

Coastline Management

  • Sediment (littoral) cells divide the coastline 

  • This cell system makes it easier for coastal planning and management 

  • Each cell has its own system of coastal planning and management

    • In England and Wales, there are 11 cells

  • Management strategies protect our coastlines from emerging threats:

    • Flooding 

    • Coastal erosion

Shoreline Management Plans

  • A Shoreline Management Plan (SMP) operates in each cell

  • SMPs consider the effects of different management strategies

  • They aim to produce better management strategies in each cell 

  • There are 4 main types of shoreline management:

    • Hold the line – using hard or soft engineering to stop the shoreline retreating from erosion

    • Managed retreat moving the coastline to a point further inland (realignment)

    • Advance the line – moving the coastline further into the sea 

    • No active intervention a typical “do-nothing”, letting natural processes occur

  • The type of management strategy depends on: 

    • The threat of coastal erosion and rising sea levels

    • How much economic or agricultural value the land may have

    • Cultural or social value the land may have

    • Environmental and ecological value

    • Cost of management strategies 

Coastal cells of England and Wales

Map of England showing major sediment cells and cell boundaries. Key indicates blue dots for sub-cell boundary, dashed red for major cell boundary, and arrows for sediment flow.
Coastal cells of England and Wales

Integrated Coastal Zone Management (ICZM) 

  • Within the coastal system, a change in one place may impact another 

  • The ICZM takes these issues into account with coastal management planning

  • The ICZM is useful for understanding the coast as an entire system of marine processes, people, the environment, and onshore and offshore activities

  • The ICZM aims to balance and manage all issues and viewpoints by:

    • Assessing what is occurring at the coast

    • Identifying all those affected and managing plans accordingly

    • Ensuring sustainability

    • Balancing the natural and the human

    • Discussing future changes and what could occur

    • Allowances for changing plans

  • This means a solution will benefit all stakeholders

Hard Engineering

  • Hard engineering is a method of coastal management

  • These are man-made structures that help to reduce the risks of coastal erosion and flooding

  • They significantly change natural coastal processes

  • They are typically expensive and damage the environment

  • Hard engineering solves issues at one point on the coast, but exacerbates issues in another area

Types of Hard Engineering 

Management strategy

Definition

Advantages

Disadvantages

Groynes

Wooden, metal or rock barriers lining the beach, perpendicular to the ocean 

Increase sediment build-up by trapping the sediment moved by longshore drift

Builds up and widens beaches

Reduces erosion in particular areas

Other areas experience increased erosion as groynes block sediment movement

They are unnatural and unattractive and prevent leisure activities

Expensive and require management

Revetments

Wooden, metal or rock slopes which absorb /deflect wave energy

Reduce erosion 

Cheaper than other hard-engineering methods

May need maintenance

Can be unattractive and prevent beach access

Sea walls

Huge concrete structures that absorb/deflect wave energy

Their curved surface protects the land from flooding caused by storm waves

Protect tourist areas e.g. beach huts

Prevent erosion 

Unattractive

Very expensive – including maintenance

Wave energy moves elsewhere, causing erosion 

Gabions

Rocks enclosed by mesh at the bottom of cliffs

Absorb wave energy

Cheaper 

Metal wires may be subject to corrosion or breakages

Unattractive and unnatural 

Riprap (rock armour)

Large boulders at the shoreline

Absorbs wave energy

Doesn’t need lots of maintenance so cost-effective in the long run

Looks more natural 

Hazardous if rocks move

Expensive to transport materials

Coastal barrages

Dam-like structures, partially submerged under the water

Keep the water level more consistent

Used for hydroelectricity 

Expensive

Not environmentally friendly

Soft Engineering

  • Soft engineering harnesses the power of nature to protect coastlines

  • It is much less damaging to the environment than hard engineering

  • It’s sustainable – it’s cheaper and more long-term

Types of Soft Engineering 

Management strategy

Definition

Advantages

Disadvantages

Beach nourishment/replenishment

Expanding the beach by moving sediment into an area that has been subject to erosion

Improves the visual aspect and functionality of beaches

Protects cliffs from erosion and inland areas from flooding risks

Requires repeated replenishment

May have negative effects on the area where sediment was removed

Cliff regrading/stabilisation 

Changing the shape of cliffs, e.g. changing the steepness of a slope

Reduces erosion and landslides

Adding vegetation can give it a more natural look

Expensive

Can cause habitat loss

Managed retreat (coastal realignment)

Leaving the shoreline to retreat naturally. Letting natural processes take over and breach current defences

Natural flooding defences can develop, e.g. salt marshes

Sustainable and cheap

People may lose housing or land

Can cause social issues

Relocation of housing is costly

Ecosystem support e.g. dune regeneration

Adding vegetation and managing natural processes

Stabilises soil, which reduces erosion risks

Looks natural and brings ecological benefits

Cheap and sustainable

Can be easily affected by adverse weather or climate change

Non-native species can impact the soil

Case Study: Holderness

Holderness Coast

Map of East Yorkshire coast showing locations of Bridlington, Skipsea, Hornsea, Mappleton, Great Cowden, Withernsea, Easington, Spurn Head, prevailing wind, and longshore drift.
The Holderness Coast
  • Located in the East Riding of Yorkshire, running from Flamborough Head to Spurn Point, the Holderness Coast is home to features of erosion and deposition, such as caves, arches, stacks, stumps and spits

  • One of the fastest-eroding coastlines in Europe

  • Soft clays make up the coastline, causing a coastal retreat of around two metres per year

  • Much land has already vanished over the past few hundred years

  • The Holderness Coast is an important place to preserve, but it is under enormous pressure and in vital need of management

Shoreline Management of the Holderness Coast

  • In 1991 in Mappleton, groynes were built to save the town and surrounding roads from coastal erosion:

    • Cost-benefit analysis showed it was cheaper to buy groynes than to rebuild a new road

    • This caused reduced sediment loads further down the coast. Increased erosion washed farmlands and livelihoods away 

  • This produced different perspectives on holding the line or doing nothing

  • Politicians and councillors held “do-nothing” views, purely from a financial perspective because it would significantly reduce costs

  • Locals favoured “holding the line”, with fears of losing their homes and farmland 

  • Spurn Head is a spit on the Holderness coastline. Here, due to storm erosion, a “do-nothing” approach was decided upon

  • Holderness Borough Council benefitted from reduced costs to protect Spurn Head

  • “Do-nothing” forced the local community to relocate

  • The Yorkshire Wildlife Trust had concerns about the importance of habitats and ecosystems and the heritage of the area

  • This Shoreline Management Plan may have been effective for some but was a failure for others

ICZM at the Holderness Coast

  • In 2000, the East Riding Yorkshire Council set up the ICZM for the East Riding Coastal Area

  • This ICZM was created because of Holderness’ main issues:

    • High erosion rates

    • Declining industries

    • Threats to communities

  • The ICZM aims to manage social, environmental and economic problems across the entire Holderness coastline

  • It also planned to re-evaluate the effectiveness and limitations of the Shoreline Management Plan

Effects and perspectives

  • The 100-page ICZM document for the East Riding coastal area sets out its ICZM strategies 

  • The document outlines differing categories for its action plan

  • Each category contains multiple policy action plans

An example of policy action plans in each category

Category

Policy action plan

Involving and implementing

Publishing the ICZM

Managing coastal change

Remove current defences that are unsafe

Transport 

Park and ride and public transport improvement

Tourism

Encourage sustainability for local businesses through guidance strategies 

Recreation 

Education programmes, warning signs and water quality information

Land use planning

Design guides for coastal villages

Rural issues

Community partnership development

Environment/nature conservation

Education and campaign on marine litter

Archaeology and the historic environment 

Create a project for coastal zone assessment to guide management decision-making

Fisheries

Improved policing of illegal activities e.g. dredging

Power generation 

Discuss the potential for wind and wave energy

Business and industry

Training and upskilling

Examiner Tips and Tricks

You don’t need to memorise the entire ICZM for East Riding. Just make sure you are aware of the reasons why the ICZM was needed and a few examples of strategies and policies.

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