|Worldwide, the impacts of coastal erosion cost hundreds of millions of Euro a year. The effects include infrastructural damage caused by storms and flooding, loss of land, and costs of erosion prevention. In Ireland, it is estimated that around 1,500 km of the coastline is susceptible to erosion, with around 490 km being in immediate danger (DELG, 2001). Rates of coastal erosion depend primarily on the erodability of coastal landforms and the strength and frequency of storms. Given that over a third of the global population, or over 2 billion people live within 100 km of a coastline, increasing efforts are being made to develop long-term sustainable coastal protection schemes.|
Erosion can be caused by a number of factors. Waves are the most important erosive agent along most coasts but their effect varies with wave energy and characteristics, and with the nature of the material exposed to wave attack (Summerfield, 1991). Where a coast is formed by steep cliffs which plunge straight into deep water, swell waves are not forced to break before they impact. As such, these waves are reflected with little loss of energy and rarely cause erosion. However, coastlines are more commonly subject to breaking waves that displace a considerable amount of kinetic energy as they break on a shoreline. Of the main types of breaking wave, 'plunging breakers' produce the highest pressures between the leading wave front and the land. The combined effect of air compression and the impact of a considerable mass of water is capable of dislodging fractured rock and other loose particles – this is known as quarrying. Breaking waves may also throw particles against the shore and this leads to the abrasion of shoreline materials – the effectiveness of this is highly dependent on wave energy and on the availability of suitable materials (e.g. pebbles) along the shore (Summerfield, 1991).
Human activity can exacerbate erosion. Dredging, mining, land reclamation and wash from ships as well as coastal protection measures themselves can all contribute to the problem (DELG, 2001).
Alternative 'soft' coastal management techniques aim to work with, and not against, natural processes. These techniques include managed realignment and beach nourishment (or recharge). Managed realignment involves the identification of a new line of defence and, where appropriate, constructing new defences landward of the original defences (DEFRA, 2001). It may be the preferred shoreline management option if the cost of maintaining the existing defences exceeds the value of the hinterland it protects, or if intertidal habitats need to be created to offset habitats lost to coastal developments. Beach nourishment involves pumping foreign sediment (often collected offshore) to raise the beach profile and to decrease the chance of coastal flooding.
Coastal Erosion in Ireland
The need to manage coastal erosion has been recognised by the Irish Government. Over €44 million were allocated in the National Development Plan 2000-2006 to address coastal erosion issues. A range of techniques have been used in different areas across the country, from dune stabilisation in Brittas Bay Co. Wicklow to the use of rock armour in Rosscarbery Co. Cork.
|Spatial Data Sources|
| The following are
suggested sources for geospatial data related to the topic:
Eurosion: Vector data at a scale of 1:100,000 regarding coastal erosion and defence structures across Europe may be downloaded from the European Environment Agency.
| Use the following
links to find more information from various organisations and online documents.
ENFO:This site provides information relating to the impact of sea-level change upon coastal erosion in Ireland.
SKOOL.IE: This site, which incorporates material for the Irish post-primary school curriculum, gives a brief overview of coastal erosion in Ireland.
Coastal Protection Expenditure Evaluation: A report prepared for the Department of Communicatons, the Marine and Natural Resources, reviewing expenditure on coastal protection schemes in the period 1998-2000.
Woods Hole Oceanographic Institution: Enter "coastal erosion" in this search engine to find information on coastal erosion issues in the United States.
NOAA Coastal Services Center: This site provides information concerning aircraft laser technology being used to determine coastal topography, coastal erosion, and shoreline position.
| The following references
were used to create the atlas pages on this topic:
Brooke, B. Beach Erosion, Geoscience Australia, [site visited 03/05/2005].
Cohen J.E., et al., 1998. Estimates of coastal populations. Science 278 (5341): pp.1211-1212.
DEFRA, 2001, Shoreline Management Plans: a Guide for Coastal Defence Authorities. Department for Environment, Food and Rural Affairs, London.
Department of the Environment and Local Government (DELG), 2001, Coastal Zone Management, Spatial Planning Unit, Dublin. [site visited 19/08/2006].
Devoy, Robert, 2003, Coastal Erosion, from The Encyclopaedia of Ireland, pp215-216, Brian Lawlor (editor), Gill and McMillan Ltd, Dublin.
Government of Ireland, 2002, National Spatial Strategy, [site visited 03/05/2005].
Summerfield, M.A., 1991, Global Geomorphology. 537 pp. Longman, Singapore.
Sylvester, A.G., 2005, UCSB Beach, 30 years of waxing and waning, University of California, [site visited 03/05/2005].
Thom, B.G. and Hall, W. 1991. Behaviour of beach profiles during accretion and erosion dominated periods. Earth Surface Processes and Landforms 16, pp. 113-127.