The Risk of Watery Reclaimations

Buildingspecifier.com’s Joe Bradbury takes a look at the growing issue of coastal erosion around the UK coastline, which is causing untold damages to homes and communities around the country.

Over the next 10 years, it is estimated that around 2,000 UK homes could fall into the sea due to coastal erosion. The wider forecast predicts we will lose over 7,000 properties (some worth over £1bn) will be lost to coastal erosion in England and Wales over the next 100 years.

The county where most homes are expected to be lost from over the next 20 years is Cornwall, with 76 properties considered high risk. Cornwall has also lost the most amount of homes to sea erosion over the last 50 years, with 132 properties collapsing or having to be abandoned due to erosion.

Throughout the course of the next century, six local authorities are expected to lose more than 200 homes each:

1. Great Yarmouth – 293
2. Southampton – 280
3. Cornwall – 273
4. North Norfolk – 237
5. East Riding of Yorkshire – 204
6. and Scarborough – 203

The east coast of Britain, in particular (from Yorkshire down to Essex) is earmarked as particularly soft and vulnerable, due to the composition of the ground and the stronger storms experienced on that side of the country.

Climate change is expected to accelerate the rate of coastal erosion overall.

An estimated 3000 km of UK coastline is eroding at an alarming rate. The UK is considered particularly vulnerable due to the fact that it has around 2300 km of artificially protected coast – the longest in Europe. Annual damages due to coastal erosion are expected to increase by 3-9 times, totalling up to £126 million per year by the 2080’s. Some 28% of the coast in England and Wales experiences erosion at rates higher than 0.1 m/year.

What can be done to help?

The answer to the increasing problem of coastal erosion is anything but simple. There are coastal defence strategies in place up and down the country, protecting 1000’s of UK households from a watery fate. However, coastal defences, such as building a wall of rock to stop waves lapping at a cliff’s base, are expensive and can have unintended consequences, such as hastening erosion elsewhere.

Unfortunately, this often means that for smaller communities in general, it’s often considered not worth the damage to the adjacent sections of the cliff or the damage to the environment that can be caused by building coastal defences.

In Britain, Shoreline Management Plans (introduced in England and Wales in 1993) serve to provide a strategic framework for decision making along the coast, especially with respect to defence, taking account of the natural coastal processes, human and other environmental influences and needs. Today the whole length of the English and Welch coast is covered by such plans; for Scotland only a part of the coast is covered by these plans. In Wales, the extent of enhanced erosion due to climate change affecting sea levels and waves is uncertain and the current view is not to build higher defences, but to utilize risk management approaches and work with nature wherever possible.

The approach to coastal protection in the United Kingdom focuses now on ‘sedimentary cells’ to reflect the adaptation needs of a regionally-varying coastline in terms of landscape, sedimentology and coastal dynamics. There are four Strategic Coastal Defence Options:

• do nothing
• maintain the existing protection line (while possibly adjusting the protection standard)
• advance the existing protection line
• retreat the existing protection line (subsequently referred to as ‘managed realignment’)

The intention is that the Shoreline Management Plans provide a ‘route map’ for local authorities and other decision makers to identify the most sustainable approaches to managing risks to the coast in the short term (0 – 20 years), medium term (20 – 50 years) and long term (50 – 100 years), recognising that changes to the present protection structures may need to be carried out as a staged process.

Methods of defence

There are multiple methods for physical management of the coast to help prevent or slow erosion.

Hard engineering are often considered to be expensive, short-term options. They also have the potential to highly impact on the landscape or environment and can be considered unsustainable.

Building a sea wall

Pros: Protects the base of cliffs, land and buildings against erosion. Can prevent coastal flooding in some areas.

Cons: Expensive to build. Curved sea walls reflect the energy of the waves back to the sea. This means that the waves remain powerful. Over time the wall may begin to erode. The cost of maintenance is high.

Building groynes (a wooden barrier built at right angles to the beach)

Pros: Prevents the movement of beach material along the coast by longshore drift. Allows the build-up of a beach. Beaches are a natural defence against erosion and an attraction for tourists.

Cons: Can be seen as unattractive. Costly to build and maintain.

Rock armour or boulder barriers

Pros: Absorb the energy of waves. Allows the build-up of a beach.

Cons: Can be expensive to obtain and transport the boulders.

Sustainable alternatives

Soft engineering options are often less expensive than hard engineering options. They are also considered more long-term and sustainable, with less of a negative impact on the environment.

There are two main types of soft engineering:

Beach nourishment

As well as being attractive to tourists, beaches are our best natural defence against erosion and coastal flooding. Beach nourishment involves replacing beach or cliff material that has been removed by erosion or longshore drift.

It’s relatively inexpensive, but requires constant maintenance to replace the beach material that is being constantly washed away.

Managed retreat

Managed retreat means that certain areas of the coast are allowed to erode and flood naturally. Usually this will be areas considered to be of low value – i.e. places not being used for housing or farmland.

The advantages are that it encourages the development of beaches (a natural defence) and salt marshes (important for the environment) and cost is low.

Managed retreat is a cheap option, but people will need to be compensated for loss of buildings and farmland.

Progress has been made

Back in March, the Environment Agency’s announced that it had reached its target of better protecting 300,000 homes from flooding and coastal erosion since 2015.

The story was picked up in The Yorkshire Post, in East Anglian Daily Times and Ipswich Star, and highlighted that the £2.6 billion investment in 700 projects had better protected nearly 600,000 acres of agricultural land and thousands of businesses and saved the economy more than £28 billion in avoided damages.

The milestone was reached with the completion of the Hull: Humber Frontages scheme, a £42 million project which will better protect the city of Hull from the devastation of tidal surges which caused flooding to hundreds of properties in 2013.

Emma Howard Boyd, Chair of the Environment Agency, said “The success of this programme is measured in numbers 700 projects, 300,000 homes, nearly 600,000 acres of agricultural land, thousands of businesses and major pieces of infrastructure, on time and within budget. But the sense of security these protections bring to people, and the benefits to nature, can’t easily be demonstrated on a spreadsheet.”

George Eustice, Environment Secretary, added “This important milestone means that 300,000 households are better protected against flooding and coastal erosion. I commend the hard work of the Environment Agency and its partners in supporting flood-hit communities.

“We know there is more to do, which is why a record £5.2 billion is being invested in 2,000 new flood and coastal erosion schemes over the next six years, to protect thousands more people, homes and businesses.”

Work is already under way on the delivery of some of the 2,000 new flood and coastal defences that will better protect a further 336,000 properties from flooding and coastal erosion by 2027, which will also see the implementation of the Environment Agency’s Flood and Coastal Risk Management Strategy.

In summary

Perhaps the biggest threat to coastal villages, towns and cities over the next 100 years is the rising sea levels due to climate change. Popular holiday destinations and vital roads in the UK could be wiped out by floods due to climate change, with many coastal and low-lying areas that could be completely submerged in water in thirty years’ time if action is not taken.

Parts of North Wales and eastern England are already predicted to be underwater by 2050 due to rising sea levels and in the south, coastal areas and river valleys would be badly affected with the M4 motorway submerged close to the Severn Bridge.

Coastal defence strategies tackle the symptoms, not the cause. In order to slow the rate that the sea level is rising we must lower our carbon footprint, protect our wetlands and allow enough natural space for rain water to soak in, rather than run off and contribute to the ocean.

Over the next 100 years we will be forced to take greater responsibility for our environment, if not for its protection then for our own!