Under the microscope: coast to coast

‘Britain is an island’

How many times have you heard that said before?! It’s a phrase with many connotations, but in simple, scientific terms, it translates to the UK having more than 19,000 miles of coastline. We are surrounded on all sides by the ocean, and that is an interaction of great interest to coastal researchers.

Our coastline is the scene of some of the most energetic – even violent –conditions in the natural environment. It acts as a natural barrier to the sea, but as we have seen in recent years (particularly here in South West England), it cannot always withstand the forces it faces. From huge amounts of sand being stripped from beaches and dunes to the rapid erosion of cliffs, we have recorded some unprecedented damage with practically all coastal communities to some degree affected by issues such as flooding and coastal retreat.

The winter storms of 2013–14, in particular, were a wake-up call for our coastal communities – and even those inland, when you consider that the damage to the railway line in Dawlish caused services to be disrupted by two months, with an economic loss to the region estimated to be between £60 million and £1.2 billion.

The impact can be devastating and profound. Many key businesses are located close to the coast – from nuclear power stations to surf clubs (not surprisingly both of which are very interested and involved with our work). It’s a situation exacerbated by the country’s propensity to erect new buildings and/or extensions in the coastal region, such as the 15,000 new houses that went up between 2005 and 2014 in coastal areas at significant risk of flooding and/or erosion.

‘Not fit for purpose’ was the stark assessment of the Committee on Climate Change when it examined the state of our current methods for protecting coastal communities. That is one of the reasons why our work has gained increasing impetus over the years. We need to be able to understand coastal dynamics if we are to move from reactive protection measures to proactively future-proofing our coastline.

This includes data on waves, tides, wind, beach profiles and aerial photography – all available on the internet. But the rest we gather ourselves and that’s one of the things that has defined us in recent years.

So what do we do at the beach? 

Well, essentially, we survey it, meaning we take many measurements that enable us to create a detailed picture of what the beach looks like, or, its topography. This survey work has changed over the years. Initially, we did it all on foot or using a quad bike. But increasingly we use drones or unmanned aerial vehicles (UAVs), which provide us with much better coverage and a similar accuracy. On foot and with a quad we can gather several thousand ‘points of data’ in a day, but from the air, that figure becomes hundreds of thousands. For the underwater part of the beach, we use a boat equipped with a single or multi-beam echosounder, which provides us with bathymetric data.

If we combine the beach topography with the underwater bathymetry and repeat measurements over different periods, for example before and after a storm, we can apply what we call a ‘total sediment approach’. It’s like counting every single sand grain, or pebble in a coastal system and how it changes over time. We survey the dunes with the UAV, and the beach with the quad and on foot, while the boat does the underwater bit. We then merge these different survey data sets together to provide a complete digital elevation model. By comparing the before and after model, we can then calculate the amount of sediment losses and gains, and the direction of transport – not a trivial task.

We also install specialist equipment in the surf zone, which provides us with some really rich data. This frame, for example, is loaded with over 100 individual sensors and meters that record the flow depth and velocity, the turbulence intensity, the position of the seabed and the amount of sand in the water. Our team will assemble the frame on the beach and position it around the low water mark. As the tide comes in, the waves begin to cover it and we can begin to see how the water and sediment move around in the surf and swash zone, and how that changes the beach.

Cameras and scanners are also key devices in our inventory as these can record data without getting in harm’s way. They are therefore ideal for monitoring extreme events. What is really important with coastal flooding is not just where the water level is but how high the waves run up and down the beach – what we call the ‘wave run-up’.

Using the cameras and the scanner, we can plot both the wave height and how far they run up the beach. On Chesil Beach in Dorset, for example, we were recording six- to seven-metre waves, which are really big, and a run-up of 10–14 metres. This gives you a feeling of how wave action can be amplified, especially on steep gravel beaches. Especially in the South West, with its large storm waves and many steep gravel beaches, it is this energetic run-up action that generally results in coastal flooding.

Today, we face some harsh realities

Our climate is changing, and the resulting rise in sea level and potential increase in storminess is having significant coastal impacts. Over time, this will only get worse, and we, as a society, have some very difficult decisions to make. There are countless homes and businesses – like those in Torcross, near Slapton – that rely upon adaptation strategies, ranging from ‘hard’ protection, such as sea walls, or more sustainable solutions such as nourishing our beaches with sand and gravel from elsewhere. But as sea levels rise, so too does the cost to the public purse: it cannot hold back the rising sea forever. Coastal Change Management Areas (CCMAs) can play a key role here. The National Planning Policy Framework requires councils to identify CCMAs, which are coastal areas likely to be affected by erosion and flooding due to climate change over the next 100 years. Residential development is ruled out in these exclusion zones, and so too is redevelopment or enlargement. We are working with several councils to help them with CCMAs – they are not straightforward to define, but they do represent a step in the right direction.

It is imperative that we future proof our dynamic coast, and for that, we need to implement an appropriate buffer zone to inform coastal planning decisions. These buffer zones will need to be site-specific and science based. They will also require regular updating in light of new data, understanding and predictions of climate change and its consequences. That is why the Coastal Processes Research Group will continue to play a key role in this field, mapping the terrain so we can better protect our coastlines now and for future generations.

We also ran a separate project looking at the impact of storms on beaches close to nuclear powerstations. The group had dedicated wave watchers who would be on high alert when a storm was forecast. They would monitor the conditions during the week and the group could then make an informed decision about whether the storm was worth ‘catching’. And when we made the call, it would mean jumping into the van and transporting all of the kit to the beach to begin the set-up. 

We became known as ‘The Storm Chasers’, and our work attracted a significant degree of interest from the media. It’s physically demanding work, but being able to respond in this way has enabled us to gather some exceptional data. Our most recent ‘chase’ came in September 2019 when we monitored the remnants of Hurricane Lorenzo, a Category 5 storm, from the beach at Crantock, near Newquay.

Coastal research tends to focus on the more exciting aspects of coastal change, such as extreme erosion. But the recovery of the coast from erosion is equally important, because if it cannot recover fully, it is vulnerable to subsequent storms. After the 2013–14 winter, we received emergency funding from the Natural Environment Research Council (NERC) to investigate not only the impacts of the extreme storms, but also the post-storm recovery of the beaches. We found that by 2016, beaches such as Perranporth in Cornwall had recovered just half of the sand lost in 2013–14. So one of the major themes behind our work since, and funded by yet another NERC grant, has been to understand and predict the rate of recovery and the role of subaerial and submerged sediment stores in the recovery process. We have based much of this work at Start Bay, in Devon, and Perranporth – which has been a great location for us over the years, dating back to when we studied rip currents with the RNLI around a decade ago.