Coastlines


 

Winter 1998

Sands of Time

Article by John Houston

A coastal system of mudflats, sandbanks and dunes has existed in the Sefton areas since the end of the last ice-age. In all that time it has never been static, it has changed shape over the centuries and responds in some way to every tide.

Climatic changes over the millennia have seen sea levels fluctuate and at times the sea has been well inland of the present day coast. The formation of the West Lancashire mosslands is a result of a falling sea level and the effect of the developing dune system in waterlogging the inland areas. Pumped drainage is now necessary to lower the water levels in the mossland to allow agriculture.

In the distant past both human inhabitants and wildlife would have moved with, and adapted to, changes in the position of the coast. In more recent times the sand dunes have been managed by the planting of marram grass and tree planting for shelter and to limit dune mobility. Artificial sea defences have been built at Southport and Crosby along former dune coasts.

Historical changes are recorded in the layers of sediment making up our coast. Reliable map records and marine charts produced from the beginning of the eighteenth centaury also show the changes along the Sefton coastline. River estuaries and associated channels are naturally mobile and, before dredging and training activities of recent times, the coast was constantly changing as it adopted to the position of the sea channels.

At Formby Point there was extensive coastal erosion during the eighteenth centaury up to about 1830. This trend reversed dramatically in the mid-nineteenth centaury, when Formby Point moved out (accreted) about 300 metres around it's whole arc. Landowners took advantage of this period to assist the advance of the dune front by means of sand trapping fences and dune management, mainly the planting of marram grass. The remains of some of these fences can been seen today on the beach near Fisherman's Path.

However from late 1880s erosion set in, spreading north and south from Victoria Road. Between 1914 and the 1970s few attempts were made to manage the coastline and the erosion was made worse by the effects of trampling by visitors. Marram grass was killed by trampling and large areas of dunes were despolit requiring long and costly restoration projects in the late 1970s and early 1980s.

The coast is subject to the effects of climate, especially winds and storm surges. It is now thought that the current phase of erosion at Formby was initiated by a significant increase in the frequency of storm force westerly winds and wave energy in the late nineteenth centaury. Some of the current predictions of climate induced change also indicate a period of increasing storminess and, if so, this could have a major impact on the future development of the Sefton Coast. The storm event on the 5th November 1998 removed several metres of dune front along the whole arc of Formby Point.

Wave and wind energy focuses on Formby Point , eroding the dunes and blowing sand inland. But sand also moves northwards and southwards along the coast, a process known as longshore drift. So, at Crosby sand moves into a 'bay' leading to sand overtopping the promenade and forming low dunes across the parkland.

Similarly at Southport there is a movement of sand from south to north. The main effect is the raising of beach levels which, in turn, encourages the development of vegetation. There is concern that vegetation growth could reduce the quality of beaches for tourism but the movement of sand has also led to the formation of a new dune ridge running the length of the beach from Ainsdale to Birkdale. The development of this feature has really been made possible by the introduction of the beach management plan closing most of the beach to traffic. Simply removing this destructive pressure has seen a natural response as the coast finds its own line.

Human intervention has constrained the natural development of the Sefton Coast for centuries, with coast defences, dredging, training walls, diversion of river channels, recreation pressure etc. Allowing the coast to find a more natural line has benefits for shoreline management. Working with nature, as far as possible, is one of the principles of modern engineering attitudes to shoreline management. The Sefton Coast is included in two Shoreline Management Plans. These will guide the preparation of local coastal policies in line with national and regional guidance.

People naturally are concerned about the risks of coastal change, to what degree nature can be left to take its course and where and when we should intervene to protect development, houses and amenities. Sefton Council is currently working on three phase coast defence project at Southport and attention is also turning to the needs for coast protection in the Hightown and Crosby areas. We are fortunate that the main dune coast from the Alt to Southport still functions in a semi-natural way and it is important that any future intervention along this part of the coast understands and works with natural processes.

A report on coast erosion at Formby was presented to the Sefton Coast Management Steering Group on 10th November 1998. The land owners affected by erosion 'all accept that the natural dynamics of the beaches and dunes must be respected. Erosion and sand mobility are key processes that help to sustain the rare habitats for which the Sefton Coast is internationally recognised. Because there is no imminent threat of flooding, any intervention must not stifle these natural processes but should rather seek to preserve habitats and maintain appropriate levels of public access.'

The Sefton Coast Management Scheme has been successful in bidding to English Nature for a grant to fund work to help the better understanding of the importance of natural processes in the conservation of soft coasts amongst local communities and visitors. The grant of 7500 is matched to European grant aid in the Life Project. The project will ran from 1998 to May 1999 with the help of Liverpool Hope University College. The grant is one of English Nature's National Conservation Development Grants for 1998/1999 and we have won this funding because the project has wider relevance to England as a whole.

What we hope to do is to find out more about people's understanding of coastal change (do people think it is inevitable, should something be done about it now, is there a real risk etc.?), use on site interpretation to better explain coastal change (e.g. by marking the position of known former shorelines) and dune processes (e.g. blowouts), use a travelling display in local libraries, publish information and develop ideas in guided walks and events.

One of the first actions was the publication of the book The Sands of Time, an introduction to the Sefton Coast, written as a popular text by Dr. Phil Smith.

This article does not express the individual views of any of the scheme partners or officers of Sefton Council. It is written to introduce some of the issues of local concern. The assistance of Tony Smith, formerly with Sefton Council's Technical Services Department, in the preparation of this article is acknowledged.