Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New coastland map could help strengthen sea defenses

08.10.2009
The 'Coastland Map' produced by scientists from Durham University and published in the Journal GSA Today, charts the post Ice-Age tilt of the UK and Ireland and current relative sea-level changes.

According to the map, the sinking effect in the south could add between 10 and 33 per cent to the projected sea-level rises caused by global warming over the next century. *

The projections are less than previous estimations for subsidence and could help local authorities to save money on sea and flood defences through the targeting of resources to areas where sea level rises will be greatest. The data and model could also be used in planning for the managed retreat of threatened coastal communities.

Since the end of the last Ice Age 20,000 years ago, land and sea-levels around the UK coastline have changed in response to the retreat of the ice sheets. As the ice melted, the release of this enormous weight resulted in the landmass slowly tilting back up in the north or down in the south, a process called isostatic adjustment.

These rises and falls come on top of any changes in sea-level caused by global warming. In Scotland, the rise of much of the coastline will offset some of the predicted rises in sea-level due to climate change.

The Durham team, led by Professor Ian Shennan and funded by the Natural Environment Research Council, looked at the relationship of peat, sand and clay sediments that have been uplifted above sea-level or are now submerged below sea level. The team radio-carbon dated samples to see how sediments formed and to calculate changes in sea-levels over thousands of years.

Eighty sites were studied around the UK and Ireland coasts. By coring and examining sediments in drainage ditches and road excavations, the team found evidence of land rises and falls from the relative elevation of sediments. These results were assessed along with previous studies of sites including the Thames, Humber, Tyne and Tees estuaries, southern England, Ireland, Wales and Scotland.

The team used the data to test models of the earth's response to ice load and this modelling technique can now be applied to other ice-affected countries with maritime boundaries, and can help predict the future of coastal areas around the world.

Prof Shennan said: "The rate of uplift north of the River Tyne to Scotland increases because the ice sheets there were thicker and heavier. The action of the Ice Age on our landmass has been like squeezing a sponge which eventually regains its shape. The earth's crust has reacted over thousands of years and is continuing to react.

"Subsidence and rising sea levels will have implications for people and habitats, and will require action to manage resorts, industrial sites, ports, beaches, salt marshes and wetlands, wildlife and bird migrations."

The new map shows how the UK and Ireland are responding to the ice sheet compression of the earth's core and the current rate of land tilt across the UK. In Northumberland, researchers found sediments from 7,000 years ago five metres below, and others from 4,000 years ago at 1 metre above the present sea level. This indicates that the sea level rose above present levels from around 7,500 years ago to 4,500 years ago, and then dropped and is continuing to fall. Sea-levels in most of Scotland peaked even higher about 4,500 years ago and have been falling ever since because the land has risen.

Sea levels 7,000 years ago were some 15 metres below the present levels in the Fenland in eastern England, and the levels are still rising. The team predicts that levels will continue to rise as the land falls, at a rate of 0.4 to 0.7 millimetres a year.

Sea-level rise brings in sediment which is soft and consolidates in coastal areas. Sea defences built on soft sediments can suffer additional subsidence due to compaction of the sediments. The Fenland is particularly affected by sediment compaction. The Thames, Bristol Channel and Kent coast are also affected as the sediment in rivers, estuaries and flood plains settles and compresses.

The three main areas of land subsidence in the UK and Ireland (see map) reflect the advance and retreat of the Scandinavian, and the British and Irish Ice Sheets.

Durham's new map and model also takes into account Newton's law of gravitational attraction and 'the Geoid effect'. Melting ice has affected the relationship between the ice, sea and land, and the mass inside the earth's mantle. These changes have produced a gravitational effect on the surface of the water in the planet's oceans.

Prof Shennan said: "When a huge mass of ice melts, the land readjusts over time but there's also a response in the earth's mantle and this affects the shape of the surface of the earth's oceans. Changes in our oceans and land uplift and subsidence will continue to have a significant effect on our coastlines this century."

Areas of falling land and rising sea levels:

Somerset, Cornwall and Devon
Dorset, Hampshire and Sussex
Kent and Essex
Suffolk and Norfolk
The Wash
Humberside and North Lincolnshire
Shetland Islands.
South Wales
Southern Ireland
Western Ireland
Areas with little land-level change
North Yorkshire; Cleveland
Mid Wales
Areas of rising land levels include:
Tyne and Wear
Northumbrian coast, Berwickshire, East Lothian,
The Firth of Forth and the Moray Forth
Fife, Aberdeenshire, Caithness
Minch and the Western Isles
Argyll, Ayrshire and the Solway Firth
Northern Irish coast
Isle of Man
Cumbria, Lancashire and Merseyside
North Wales

Carl Stiansen | EurekAlert!
Further information:
http://www.dur.ac.uk

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>