Identifying storm impacts on an embayed, high-energy coastline: examples from western Ireland

Andrew Cooper, Derek Jackson, F Navas, John McKenna, G Malvarez

Research output: Contribution to journalArticle

96 Citations (Scopus)

Abstract

Large sections of the western Irish coast are characterised by a highly compartmentalised series of headland-embayment cells in which sand and gravel beaches are backed by large vegetated dune systems. Exposure to modally high-energy swell renders most of these beaches dissipative in character. A mesotidal range (c. 3.5-4.5 m) exists along much of the coast. Analysis of instrumental wind records from three locations permitted the identification of a variety of storm types and the construction of storm catalogues. Few individual storms were recorded at all three stations indicating a lack of regional consistency in storm record. Of the total storms recorded, only a small percentage are potentially damaging (onshore directed) and even fewer span a high tide and thus potentially induce a measurable morphological response at the coast. Through a combination of historical records, meteorological records, field observations and wave modelling we attempt to assess the impact of storms. Quantifiable records of coastal morphology (maps, air photos and beach profiles) are few in number and do not generally record responses that may be definitely attributed to specific storms. Numerical wave simulations and observations at a variety of sites on the west Irish coast, however, provide insights into instantaneous and medium term (decadal) storm responses in such systems. We argue that beaches and dunes that are attuned to modally high-energy regimes require extreme storms to cause significant morphological impact. The varying orientation of beaches, a spatially nonuniform storm catalogue and the need for a storm to occur at high water to produce measurable change, impart site-specific storm susceptibility to these embayments. Furthermore, we argue that long-period wave energy attenuation across dissipative shorefaces and beaches reduces coastal response to distant storms whereas short-period, locally generated wind waves are more likely to cause major dune and beach erosion as they arrive at the shoreline unrefracted. This apparently variable response of beach and dune systems to storm forcing at a decadal scale over a coastline length of 200 kin urges caution in generalising regarding regional-scale coastal responses to climatic change. (C) 2004 Elsevier B.V. All rights reserved.
LanguageEnglish
Pages261-280
JournalMarine Geology
Volume210
Issue number1-4, S
DOIs
Publication statusPublished - Sep 2004

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coast
energy
beach
dune
coastal morphology
beach erosion
wave modeling
beach profile
wind wave
historical record
swell
sand and gravel
wave energy
shoreline
tide
climate change
air
simulation

Cite this

Cooper, Andrew ; Jackson, Derek ; Navas, F ; McKenna, John ; Malvarez, G. / Identifying storm impacts on an embayed, high-energy coastline: examples from western Ireland. In: Marine Geology. 2004 ; Vol. 210, No. 1-4, S. pp. 261-280.
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abstract = "Large sections of the western Irish coast are characterised by a highly compartmentalised series of headland-embayment cells in which sand and gravel beaches are backed by large vegetated dune systems. Exposure to modally high-energy swell renders most of these beaches dissipative in character. A mesotidal range (c. 3.5-4.5 m) exists along much of the coast. Analysis of instrumental wind records from three locations permitted the identification of a variety of storm types and the construction of storm catalogues. Few individual storms were recorded at all three stations indicating a lack of regional consistency in storm record. Of the total storms recorded, only a small percentage are potentially damaging (onshore directed) and even fewer span a high tide and thus potentially induce a measurable morphological response at the coast. Through a combination of historical records, meteorological records, field observations and wave modelling we attempt to assess the impact of storms. Quantifiable records of coastal morphology (maps, air photos and beach profiles) are few in number and do not generally record responses that may be definitely attributed to specific storms. Numerical wave simulations and observations at a variety of sites on the west Irish coast, however, provide insights into instantaneous and medium term (decadal) storm responses in such systems. We argue that beaches and dunes that are attuned to modally high-energy regimes require extreme storms to cause significant morphological impact. The varying orientation of beaches, a spatially nonuniform storm catalogue and the need for a storm to occur at high water to produce measurable change, impart site-specific storm susceptibility to these embayments. Furthermore, we argue that long-period wave energy attenuation across dissipative shorefaces and beaches reduces coastal response to distant storms whereas short-period, locally generated wind waves are more likely to cause major dune and beach erosion as they arrive at the shoreline unrefracted. This apparently variable response of beach and dune systems to storm forcing at a decadal scale over a coastline length of 200 kin urges caution in generalising regarding regional-scale coastal responses to climatic change. (C) 2004 Elsevier B.V. All rights reserved.",
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Identifying storm impacts on an embayed, high-energy coastline: examples from western Ireland. / Cooper, Andrew; Jackson, Derek; Navas, F; McKenna, John; Malvarez, G.

In: Marine Geology, Vol. 210, No. 1-4, S, 09.2004, p. 261-280.

Research output: Contribution to journalArticle

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