SCIENTISTS AT Newcastle University are using satellite technology to produce the first accurate map of Britain's movements with tidal changes.
The country 'bounces' with the tide. As the weight of water increases on the continental shelf around Britain's coast, the whole country sinks a little into the earth's crust, rebounding as the tide recedes. Parts of Cornwall, for example, rise and fall by about 100mm every day.
The problem for engineers is that the land does not sink evenly, resulting in local distortions which cause inaccuracies when satellite surveying techniques are used in construction projects.
Civil engineers will be able to account for the change in levels when building bridges, dams or tunnels. Millions of pounds could be saved on large construction projects using the technology which could make surveying a lot more accurate, researchers said.
Dr Peter Clarke of the Department of Geomatics at Newcastle University, is leading a research team which is using orbiting US satellites to monitor the positions of more than 30 global positioning system (GPS) receivers around Britain. The measurements are within an accuracy of a millimetre or two. It should then be possible to estimate the 'bounce factor' in any part of the country at any time.
Although 'bounce' has previously been measured by similar techniques in the US and other countries, accurate and comprehensive national maps have never been produced.
'The phenomenon has been known about for some time but it has only become necessary to measure these movements because of the increasing use of precise satellite surveying by civil engineers, ' said Clarke.
'Our measurements will be used to adjust the data obtained by surveying to produce results which are perhaps ten times more accurate - to within millimetres rather than centimetres. This could significantly reduce the cost of large construction projects. '
The Natural Environment Research Council has given £64,000 to the project, which also involves the Proudman Oceanographic Laboratory and Ordnance Survey, with help from the National GPS Archive at Nottingham University. The project is due to be fin-