'Machair,' Says Coastal Zone Expert 21 November 2012, by David Young

Misconceived sea defence measures will destroy 'machair,' says coastal zone expert 21 November 2012, by David Young be over, but in the Western Isles we have discovered a whole new chain of barrier islands very close to home: they've been there all the time, but we had not previously recognised their true nature," he said. "There is a continuous line of sand along the western coast of the islands - known as machair, a kind of flat sandy plain that is draped over the underlying rock. The machair is the main part of the islands that can be farmed, as the rest is rocky. It's seen as a cultural landscape, tied to the crofting Professor Andrew Cooper of the University of Ulster. lifestyle. "When we took a close look at the beaches and machair, we realised that they are actually barrier (Phys.org)—The traditional crofting way of life is islands. Barrier islands are long strips of sand with under threat in Scotland's Western Isles because tidal inlets at either end, and they are separated of a fundamental misunderstanding of how Atlantic from the mainland by a body of water." wave action affects their coastlines, a University of Ulster academic has revealed. In the Western Isles, Professor Cooper observed, the bodies of water tend to be quite shallow, and Research published in the latest issue of the the tidal inlets are very small, but when you look at leading international journal Geology by Professor their overall shape, you can see that they are in fact Andrew Cooper of the University of Ulster in barrier islands. conjunction with colleagues in the Universities of Aberdeen, Dundee and St Andrew's, has "It's an unusual setting in which to find barrier discovered that the beaches and machair of the islands: normally, you find them on low lying Uists and Benbecula are an unusual type of coastal plains, not storm-battered rocky coastlines "barrier island' that are more typical of coasts like at nearly 60 degrees north. It is a very unusual set those of the eastern USA. of circumstances that allows them to exist in the west of Scotland." Barrier islands survive by rolling landwards as sea levels rise and storms buffet the coast. Rather than Recognising that these are in fact barrier islands is being lost offshore, sand is conserved and pushed vital for their environmental management, he landwards, raising the surface of the islands as argued. they move landwards. "Farmers that live and work on them have long However Professor Cooper is concerned that sea thought that the islands are being eroded, with defence measures will prevent that process from sand being stripped from them and carried out to taking place and will actually destroy the islands' sea," Professor Cooper said. fragile agricultural ecosystem. "Now, that we understand that they are in fact "The great days of exploration and discovery may barrier islands, we know that that kind of erosion is 1 / 2 not what is happening at all, Instead of sand being carried out to sea, it is in fact being push landwards – almost like rolling up a carpet. The sand is moving from the front of the barrier island to the back: over time, it gradually rolls in a landward direction. "Unfortunately, following big storms in 2006, a lot of sea walls have been built along the seaward edge of the islands in the mistaken belief that they will stop erosion – in fact, they are stopping the barrier islands' natural tendency to roll landwards. "Ironically, by stopping the sand from moving, being flexible, we are destroying the coastal environment. We think that by holding the sand in one place we are protecting the machair, but we're not. "There is a lot of work that needs to be done in the area for people there to understand how barrier islands work, and to help them understand that for barrier islands, erosion is not a threat – it is the life blood of the islands. Without erosion and landward migration of the sands the islands are going to die. If you just put walls around them they will just get locked in and will eventually be submerged. "That would spell the end of the crofting lifestyle for the thousands of people who live on the islands." With this new understanding of how the coasts of the islands work, Professor Cooper hopes new environmental management strategies can be developed that will help – rather than hinder – the survival of the machair and the traditional lifestyles that depend upon it. Provided by University of Ulster APA citation: Misconceived sea defence measures will destroy 'machair,' says coastal zone expert (2012, November 21) retrieved 3 October 2021 from https://phys.org/news/2012-11-misconceived- seadefence-measureswill-destroymachair-coastal.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. 2 / 2 Powered by TCPDF (www.tcpdf.org).

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