Coastal Processes: Human Impacts and Implications

Social Consequences and Displacement

Buying a home is usually a lifelong investment, but for some coastal residents, it becomes a nightmare as the cliff edge approaches. Social displacement occurs when people are forced to abandon their homes due to environmental hazards.

• On the Holderness Coast, the shoreline retreats at an average of 2 metres per year because the cliffs are made of unconsolidated boulder clay.
• Since Roman times, over 30 villages along this coast have been lost entirely to the sea.
• In the Norfolk village of Happisburgh, more than 26 houses have been lost in recent decades, and its 14th-century church is highly threatened, leading to a deep loss of cultural heritage.

This physical threat is worsened by demographic ageing in coastal towns.

• Around 21% of coastal residents are aged 65 or over (compared to 18% inland).
• This creates high social vulnerability, as elderly populations often have lower physical mobility for evacuations and live on fixed pensions, meaning they cannot afford property-level flood defences.
• The constant threat causes severe psychological "blight", leaving communities feeling trapped and fragmented.

Economic Impacts on Livelihoods and Infrastructure

A single collapsed railway line can cost the national economy over a billion pounds. The economic consequences of coastal processes are vast, categorized into direct (structural damage) and indirect (business closures) economic loss.

• The 2014 collapse of the Dawlish rail line in Devon severed Cornwall's transport link for two months, costing the UK economy £1.2 billion.
• National energy security is also at risk; the Easington Gas Terminal handles 25% of the UK's total gas supply but sits just 25 metres from the eroding Holderness cliff edge.
• Farmland, valued between £12,000 and £50,000 per acre, is regularly lost; for example, one farmer at Ringborough Farm lost half of his 145 acres to the sea, forcing him to diversify his business to survive.

Residents also face a severe financial penalty known as insurance blight.

• While the UK government's Flood Re scheme caps flood insurance excesses at £250 for eligible homes, it does not cover land lost to coastal erosion.
• Because there is no national compensation for erosion, homes in high-risk zones become completely uninsurable and unsellable.
• When comparing impacts globally, developed nations like the UK face high monetary losses due to expensive infrastructure, whereas developing nations like Bangladesh (which lost between US$1.7 billion and US$2.31 billion in Cyclone Sidr) suffer higher proportional economic losses and greater loss of life.

Environmental Consequences: Coastal Squeeze

What happens when natural habitats have nowhere left to go? As sea levels rise against man-made sea defences, ecosystems experience coastal squeeze.

• This process traps natural buffers like saltmarshes and sand dunes against concrete walls, preventing them from migrating inland and causing their destruction.
• This is devastating for conservation, placing 1,531 hectares of English coastal SSSI (Sites of Special Scientific Interest) floodplain habitats at immediate risk.
• Losing these habitats removes natural protection; healthy saltmarshes can reduce wave energy by up to 80%.
• Rare species are directly threatened, such as the Bittern bird on the Suffolk Coast, which relies on vulnerable freshwater reedbeds.

The Impact of Coastal Management Strategies

Every time you build a sea wall to protect one town, another village downdrift might suffer the consequences. Intervening in coastal processes involves either hard engineering or soft engineering.

• Hard engineering is expensive and creates stakeholder conflict. At Mappleton, two granite groynes costing £2 million were built to protect 20 local jobs and the vital B1242 road.
• However, this caused Terminal Groyne Syndrome downdrift at Great Cowden, starving the beach of sediment and accelerating erosion from 1 metre/year to 3 metres/year, destroying 100 holiday chalets.
• Alternatively, managed retreat allows low-value land to flood to create natural defences.
• The Medmerry project in West Sussex cost £28 million to construct a 7 km inland embankment, but it sustainably protects 348 homes while creating new saltmarsh habitats.

Calculating Coastal Recession

Geographers calculate the severity of erosion by determining the rate of coastal recession over time.

$$\text{Recession Rate} = \frac{\text{Distance of Retreat (m)}}{\text{Time Period (years)}}$$

A section of the Holderness cliff retreats 15 metres between 2015 and 2025. Calculate the annual rate of recession.

Step 1: Identify the values.

• Distance of retreat = 15 m
• Time period = $2025 - 2015 = 10$ years

Step 2: Substitute into the equation.

• $\text{Recession Rate} = \frac{15}{10}$

Step 3: Calculate and state the units.

• $\text{Recession Rate} = 1.5\,\text{m/year}$