̽��ֱ�� of Cambridge - Cambridge Coastal Research Unit

Sea change for Hull

lw355 — Fri, 16 Dec 2022 08:55:44 +0000

With a changing climate and rising sea levels putting cities at risk of flooding, it’s crucial for planners to increase their cities’ resilience. A new tool has been developed to help them – and it started with the throwing of a thousand virtual hexagons over Hull.

Sea Change

sc604 — Fri, 22 Mar 2019 09:13:26 +0000

̽��ֱ��coast is an intrinsic part of British identity – and perhaps nowhere is it more at risk than in the East of England. Cambridge researchers are working with communities and organisations across the region to manage the coast for the future, by working with nature rather than against it.

Cambridge researchers learn lessons from recent storm surge

jfp40 — Thu, 16 Jan 2014 12:20:31 +0000

̽��ֱ��wet and windy weather that has battered Britain’s coasts this winter has brought misery to many, but for researchers at the ̽��ֱ�� at Cambridge the storm damage is providing vital data that could help improve future flood warnings and emergency planning.

On 5 December 2013, coastal communities along the North Norfolk coast were threatened by a significant storm surge – the result of low atmospheric pressure (which causes sea level to rise) combined with high winds pushing up the sea surface as they blow water towards the coast.

According to Dr Tom Spencer of the Department of Geography’s Cambridge Coastal Research Unit: “ ̽��ֱ��southern North Sea is very vulnerable to storm surges because of its shallow water, and winds blowing from north to south funnel the sea into the narrowing basin near the Straits of Dover.”

Predicting the impact of storm surges on coastal areas like North Norfolk, which is lined with barrier islands and gravel spits – and cut by tidal inlets bordered by mudflats and saltmarshes, is challenging. To find out how these features affected the water levels and waves that hit the area’s coastal settlements during the storm, the team from Cambridge and Birkbeck, ̽��ֱ�� of London took to the road.

Immediately after the surge, they travelled the 45km between Holme-next-the-Sea and Salthouse measuring maximum water levels with a satellite-based survey system able to resolve positions and heights to an accuracy of less than 50mm and often less than 20mm. “We looked for debris lines, erosion marks on earthen banks and floodlines on buildings – or in some cases car windscreens,” Dr Spencer explained.

They found that maximum surge heights here differed by almost 2m, depending on whether the site was exposed or sheltered, differences much larger than previously thought. “At some sites this was the critical difference between a business or a home being flooded or not,” said Dr Spencer. If these results can be incorporated into surge models and flood forecasts, they could help improve early warning systems and evacuation planning.”

̽��ֱ��December 2013 event that Dr Spencer studied came almost exactly 60 years after the disastrous storm that hit the region in 1953, claiming more than 2,000 lives around the southern North Sea – the largest death toll from flooding in Europe for 100 years.

“Looking at the atmospheric pressure charts, the 2013 and the 1953 events look similar: both were characterised by a deep low pressure system that came down the long axis of the North Sea. But while the 2013 storm was short-lived, producing waves of around 3.8m offshore from North Norfolk, in 1953 gale force winds blew for several days ahead of the surge, producing waves probably close to 8m high off eastern England,” he says.

Like the 2013 event, the 1953 storm arrived under cover of darkness. But unlike 2013, it hit over the weekend, with devastating results.

“Most people in the UK and ̽��ֱ��Netherlands were asleep in bed when floodwaters broke into their houses, many of which were single storey chalets and bungalows. Some people managed to get onto their roofs but, with the storm still raging, they died from exposure or slid into the sea,” he said. “In ̽��ֱ��Netherlands, where over 1,800 lives were lost, the radio ceased transmitting at midnight on the Saturday and although warnings were issued by telegram, these arrived at offices that were shut over the weekend.”

Much was learned from the 1953 storm: coastal defences were heightened and strengthened, and there have been major advances in storm surge forecasting and emergency planning. But, as Dr Spencer’s results show, there are still lessons to be learned from today’s floods that could help prevent tomorrow’s victims.

̽��ֱ��team’s initial assessment is published in Nature.

For researchers at the ̽��ֱ�� at Cambridge, recent storm damage is providing vital data that could help improve future flood warnings and emergency planning

These results could help improve early warning systems and evacuation planning

Tom Spencer

I Moeller

Stranded boat at Blakeney after storm surge

This work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page.

Yes

After the flood: harnessing the power of mud

hps25 — Thu, 31 Jan 2013 12:46:44 +0000

Sixty years ago tonight, a storm surge in the North Sea caused catastrophic flooding on the coast of eastern England. ̽��ֱ��‘big flood’ of 1953 inundated more than 65,000 hectares of land, damaged 24,000 houses and around 200 important industrial premises, resulting in 307 deaths in the immediate flooding phase.

In the aftermath, sea defences were developed and major protection schemes were implemented – the eventual construction of the Thames Barrier being the most conspicuous example. Warning services and emergency responses to flooding became coordinated at a national level, something which hadn’t existed in 1953.

But many of these reinforcements will reach the end of their design life in the next decade. Experts analysing storm surge height and wave activity believe the flood to be a once every 50 year event – it will happen again, they say, it is only a question of when.

Environmental changes and possible sea-level rises hadn’t been properly anticipated when protection schemes commenced, and UK coastal populations have risen by up to 90% in certain areas since 1953 – many designated as high flood risk.

“Such contexts call for more research into complexities of storm surge dynamics, strengthening of coastal planning policy and a more nuanced approach to coastal engineering,” said Dr Tom Spencer, Director of the Cambridge Coastal Research Unit (CCRU) from the Department of Geography.

̽��ֱ��CCRU are currently researching the effectiveness of the natural flood defences offered by coastal ecosystems such as salt marshes and mud flats. They suggest a ‘hybrid engineering’ approach, combining sea walls with natural ecosystems. Such ecosystems not only provide flood protection but store carbon, filter pollutants and increase biodiversity. Over recent years, these important habitats that have become “squeezed out” by rising sea levels and hard sea defences.

̽��ֱ��research is part of a six year programme involving 14 other institutions, funded by the Natural Environment Research Council. ̽��ֱ��teams are focusing on the marshlands of the Essex coast and Morecambe Bay.

“We already know that some of the Essex marshes regularly reduce the energy of waves by up to 90% over a distance of 80 metres or so,” said Dr Iris Möller, Lecturer in Physical Geography at Fitzwilliam College and co-investigator on the project.

“Hard defences are expensive and doomed to fail or incur ever-increasing costs. A key priority is the need to restore a natural coastal ‘buffer’ zone, free from human occupation and compatible with the ‘inbuilt’ ability of the coast to respond dynamically to environmental change – such as sea level rise or more frequent storms.”

̽��ֱ��researchers say they now have the technology to accurately measure wave depth and energy across marshes and mud flats, providing engineers and policy makers with the information they need to show the effectiveness of ecosystem-inclusive sea defence systems.

By installing a total of 42 wave recording devices at marshes in Essex and Morecambe Bay, with measurements controlled by solar-powered data logging systems, the team can track wave level and pressure variations as water moves across mud and vegetation. This information is continuously streamed back to Cambridge via mobile phone networks.

̽��ֱ��team are finding that the mud and plants of the marshes naturally dissipate the ferocity of waves from storms, whereas just seawalls can alter the shape of the coast artificially, causing greater erosion through energy redistribution.

̽��ֱ��Cambridge wave research is part of the Coastal Biodiversity and Ecosystem Services Sustainability project, looking at the range of benefits natural ecosystems can provide – from carbon stores to pollution sinks as well as wave buffers – and how they can integrate with traditional flooding engineering.

“It is important to understand the value of varied habitats that make up the landscape of the UK,” said Professor David Paterson, project leader from the ̽��ֱ�� of St. Andrews. “Coastal systems are some of the most sensitive to pressures of climate change”.

Adds Spencer: “It’s vital that we also investigate the role of ecosystems in coastal risk reduction and how, through ‘hybrid engineering’, both types of approach to coastal defence can be brought together to reduce risks and provide a long-term and robust response to the threat of catastrophic coastal flooding.”

On the 60th Anniversary of the ‘big flood’ that devastated the coastline of eastern England, new research shows that integrating ‘natural’ sea defences such as salt marshes with sea walls is a more sustainable and effective method of flood prevention.

Both types of approach to coastal defence can be brought together to reduce risks and provide a long-term and robust response to the threat of catastrophic coastal flooding.

Tom Spencer

Dr Iris Moller

Mudflat and marsh at Abbots Hall, Essex

This work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page.

Yes