The plan to save Norfolk coast will only put off the inevitable

The coast near Bacton, Norfolk. Image: Getty.

This summer, the UK’s Norfolk coast underwent a transformation that has only been seen once in the world before. A giant sandscaping scheme saw 1.8m cubic metres of sand added to the area’s beaches to reshape them as a way of reducing coastal erosion. This is an amazing engineering defence, designed to increase the resilience of the adjacent cliffs to erosion. But it may have a sting in its tail in a generation’s time.

Bacton cliff was created from a mixture of debris left by large ice sheets thousands of years ago. Unprotected, the cliffs erode at a rate of a metre a year. The area’s current sea defences including groynes – barriers that stretch out from the shore to limit the movement of sediment – slow down the erosion, but don’t stop it. This means that during extreme storm events, such as in 2013-2014, some five metres to ten metres of cliff can be lost overnight.

Perilously close to the cliff edge is a nationally important Bacton gas terminal, supplying up to one third of the UK’s natural gas after it is brought ashore from the North Sea gas fields. Years of erosion have left just 15 metres between the terminal and the cliff edge. Coastal oil and gas facilities threatened by erosion often have hard rock armouring or groynes placed immediately in front of the cliffs they sit on.

However, history tell us this can actually increase erosion on the adjacent coast. Sand gets trapped between groynes and cannot move to offer protection elsewhere. This means engineers cannot simply build more or bigger groynes in front of the Bacton terminal.

The Zand Motor (or Sand Engine) in the Netherlands. Image: Zand Motor/Flickr.

A common alternative solution is to nourish beaches with extra sand or shingle. This helps build a bigger beach to stop the waves reaching the cliff and so reduces erosion. But this only lasts a short period of time before the new sand is washed away.

In 2011, the Netherlands piloted mega-sand nourishment or “sandscaping”, known as the Zand Motor (or Sand Engine), creating a new 1km by 2km beach near The Hague. The 21.5m cubic metres of sand was designed to protect the coast for 20 years, but is now expected to last longer. The Zand Motor also brought some unexpected benefits. Instead of just being seem as a giant coastal protection scheme, it also has become a place for recreation such jogging or kite surfing.

Bacton is now attempting a similar sandscaping. If all the sand being used were piled a metre high, it would cover an area the size of 200 football pitches. In practice, the sand dune will be built up to seven metres high in places.

The benefits of the scheme are immense. Although principally protecting the gas terminal, the dune will extend up and down the coastline around it, protecting 100 homes and the coastal road to the south. Tourism may also increase, with benefits and business opportunities for those nearby.

Yet while resilience to erosion and flooding will increase for now, the sand will slowly be moved by the waves, and in a few decades the sandscape will be gone. Local residents and businesses may expect that a second sandscaping project will follow. But, presently, no such security exists. The long-term issues of a retreating coastline will manifest itself once again in a generation’s time.

The council’s Shoreline Management Plan includes options to try to take further measures to hold the current coastline, do nothing, or realign the coastline landwards of its present position by removing defences as they reach the end of their life. The long-term plan for Bacton and nearby villages in 40 to 90 years is for coastal retreat. This means defunct defences will be removed and the coast will be allowed to erode naturally. Part of the coastal road and nearby homes will be lost to the sea.

This will be preceded by a transition period, which will be vital to allow local residents to adjust to the idea of coastal change. But the sandscaping project could do exactly the opposite as it raises expectations of long-term protection and could discourage people from coming to terms with the problem.


Community adjustment

The local authority is all too aware of the issues of retreating from the coast. Time and money is needed to assess the options and invest in coastal communities, so they can better cope with the transition. At nearby Trimmingham, a new village hall and community hub opened in 2018 to replace one near the cliff edge. Elsewhere, government support to relocate or “roll back” dwellings is helping householders or small businesses with the practicalities of adapting to the eroding coast.

The sandscaping project may raise the hopes of other coastal communities outside Norfolk that similar schemes could help them too. But the huge costs mean sandscaping is only likely where there is significant non-government investment – £12m of the £22m cost of the Bacton sandscaping scheme was funded by the gas terminal operators. This means we may only see sandscaping next to large, nationally important infrastructure.

Managing the coastline will only get harder as sea levels rise and budgets are squeezed. Engineers can’t keep protecting the whole coast indefinitely, and difficult decisions will have to be made over what to protect, how and for how long. The Bacton sandscaping can buy time to prepare people for a slow, dignified retreat. But while the community may have won the battle against erosion, it will ultimately lose the war.

The Conversation

Sally Brown, Senior Research Fellow, University of Southampton.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

Green roofs improve cities – so why don’t all buildings have them?

The green roof at the Kennedy Centre, Washington DC. Image: Getty.

Rooftops covered with grass, vegetable gardens and lush foliage are now a common sight in many cities around the world. More and more private companies and city authorities are investing in green roofs, drawn to their wide-ranging benefits which include savings on energy costs, mitigating the risk from floods, creating habitats for urban wildlife, tackling air pollution and urban heat and even producing food.

A recent report in the UK suggested that the green roof market there is expanding at a rate of 17 per cent each year. The world’s largest rooftop farm will open in Paris in 2020, superseding similar schemes in New York City and Chicago. Stuttgart, in Germany, is thought of as “the green roof capital of Europe”, while Singapore is even installing green roofs on buses.

These increasingly radical urban designs can help cities adapt to the monumental challenges they face, such as access to resources and a lack of green space due to development. But buy-in from city authorities, businesses and other institutions is crucial to ensuring their success – as is research investigating different options to suit the variety of rooftop spaces found in cities.

A growing trend

The UK is relatively new to developing green roofs, and governments and institutions are playing a major role in spreading the practice. London is home to much of the UK’s green roof market, mainly due to forward-thinking policies such as the 2008 London Plan, which paved the way to more than double the area of green roofs in the capital.

Although London has led the way, there are now “living labs” at the Universities of Sheffield and Salford which are helping to establish the precedent elsewhere. The IGNITION project – led by the Greater Manchester Combined Authority – involves the development of a living lab at the University of Salford, with the aim of uncovering ways to convince developers and investors to adopt green roofs.

Ongoing research is showcasing how green roofs can integrate with living walls and sustainable drainage systems on the ground, such as street trees, to better manage water and make the built environment more sustainable.

Research is also demonstrating the social value of green roofs. Doctors are increasingly prescribing time spent gardening outdoors for patients dealiong with anxiety and depression. And research has found that access to even the most basic green spaces can provide a better quality of life for dementia sufferers and help prevent obesity.

An edible roof at Fenway Park, stadium of the Boston Red Sox. Image: Michael Hardman/author provided.

In North America, green roofs have become mainstream, with a wide array of expansive, accessible and food-producing roofs installed in buildings. Again, city leaders and authorities have helped push the movement forward – only recently, San Francisco created a policy requiring new buildings to have green roofs. Toronto has policies dating from the 1990s, encouraging the development of urban farms on rooftops.

These countries also benefit from having newer buildings, which make it easier to install green roofs. Being able to store and distribute water right across the rooftop is crucial to maintaining the plants on any green roof – especially on “edible roofs” which farm fruit and vegetables. And it’s much easier to create this capacity in newer buildings, which can typically hold greater weight, than retro-fit old ones. Having a stronger roof also makes it easier to grow a greater variety of plants, since the soil can be deeper.


The new normal?

For green roofs to become the norm for new developments, there needs to be buy-in from public authorities and private actors. Those responsible for maintaining buildings may have to acquire new skills, such as landscaping, and in some cases volunteers may be needed to help out. Other considerations include installing drainage paths, meeting health and safety requirements and perhaps allowing access for the public, as well as planning restrictions and disruption from regular ativities in and around the buildings during installation.

To convince investors and developers that installing green roofs is worthwhile, economic arguments are still the most important. The term “natural capital” has been developed to explain the economic value of nature; for example, measuring the money saved by installing natural solutions to protect against flood damage, adapt to climate change or help people lead healthier and happier lives.

As the expertise about green roofs grows, official standards have been developed to ensure that they are designed, built and maintained properly, and function well. Improvements in the science and technology underpinning green roof development have also led to new variations on the concept.

For example, “blue roofs” increase the capacity of buildings to hold water over longer periods of time, rather than drain away quickly – crucial in times of heavier rainfall. There are also combinations of green roofs with solar panels, and “brown roofs” which are wilder in nature and maximise biodiversity.

If the trend continues, it could create new jobs and a more vibrant and sustainable local food economy – alongside many other benefits. There are still barriers to overcome, but the evidence so far indicates that green roofs have the potential to transform cities and help them function sustainably long into the future. The success stories need to be studied and replicated elsewhere, to make green, blue, brown and food-producing roofs the norm in cities around the world.

Michael Hardman, Senior Lecturer in Urban Geography, University of Salford and Nick Davies, Research Fellow, University of Salford.

This article is republished from The Conversation under a Creative Commons license. Read the original article.