Coastal Erosion & Flooding Strategies (DP IB Geography)
Revision Note
Written by: Grace Bower
Reviewed by: Bridgette Barrett
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
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
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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