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 NASA examines newly formed Tropical Depression 3W in 3-D
26.04.2017 | NASA/Goddard Space Flight Center

nachricht Early organic carbon got deep burial in mantle
25.04.2017 | Rice University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>