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www.elsevier.com/locate/margeo

Marine Geology xx (2004) xxx–xxx

FIdentifying storm impacts on an embayed, high-energy coastline:

examples from western Ireland

J.A.G. Cooper*, D.W.T. Jackson, F. Navas, J. McKenna, G. Malvarez

Coastal Studies Research Group, School of Biological and Environmental Sciences, University of Ulster, Coleraine BT52 1SA,

County Londonderry, Northern Ireland, UK
OReceived 20 November 2002; received in revised form 10 September 2003; accepted 3 May 2004
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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 km urges caution in generalising regarding regional-scale coastal responses to climatic change.
CD 2004 Published by Elsevier B.V. N U 3233
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0025-3227/$ - see front matter D 2004 Published by Elsevier B.V.

doi:10.1016/j.margeo.2004.05.012

* Corresponding author.

E-mail address: [email protected] (J.A.G. Cooper).

1. Introduction

The west coast of Ireland is exposed to the North

Atlantic at latitudes between 51.5j and 55.5j North.

The coastline (Fig. 1) is framed by crystalline

MARGO-03535; No of Pages 20

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Fig. 1. Locality map showing weather stations (Valentia, Belmullet, Malin) and coastal sites studied. Note the high variability in orientation of

sites. Shaded boxes illustrate initial wave simulation grids from which deep-water waves were propagated into shallow waters through

successively smaller computational grids.

J.A.G. Cooper et al. / Marine Geology xx (2004) xxx–xxx2

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J.A.G. Cooper et al. / Marine Geology xx (2004) xxx–xxx 3

bedrock and has an irregular and highly indented

morphology. Littoral deposits derived mainly from

reworked glacial sediments typically form in embay-

ments as mainland-backed beaches or barriers at the

mouths of estuaries (Carter, 1988). Due to a high-

energy swell environment and availability of fine

grained, sandy sediment, most of the headland-em-

bayment beaches are sandy and in a fully dissipative

state with low cross-shore gradients. Contemporary

sediment supply is minimal and each embayment

appears to contain a fixed sediment volume. Tidal

range within this semidiurnal environment is com-

paratively high, with spring tidal range along most of

the western Irish coast between 3.5 and 4.5 m.

Dunes typically occur at elevations about 0.5 m

above spring high tide levels and are fronted by

wide, low gradient beaches (Fig. 2).

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Fig. 2. Beach profiles from selected sites (Magilligan, Gweebarra, Rossno

water mark based on tide table data. Note the wide, low gradient beach

overwash as a morphological response to storms.

OOF

Modal wave and wind energy levels are high and

the island lies in the path of several common storm

tracks (Lozano and Devoy, 2000; Lozano et al., this

volume). The most commonly identified coastal mor-

phological response to wave effects during storms is

manifest in dune scarping (Carter and Stone, 1989;

Orford et al., 1999), although distinctive beach surfi-

cial structures may be formed by wave-driven foam

(Cooper and Jackson, 2001) and wave-spray-induced

supratidal deposition has been recorded (Cooper and

Jackson, 1999).

Swell refraction over the irregular sea floor and

around the indented shoreline has produced a series

of beach equilibrium plan forms that typically show

little net morphological change on an annual basis

and are also stable in the medium term (Carter,

1988). The orientation of beaches is determined by

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wlagh and Inch). HWM=mean high water mark, LWM=mean low

backed by extensive sand dunes in each instance which preclude

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EC

swell refraction and most appear to be swash-aligned

(Carter, 1988). Most beaches in western Ireland are

backed by extensive dune systems that are deca-

metres high and several 100 s of metres wide. This

morphological configuration precludes barrier over-

wash during storms and constrains coastal morpho-

logical response to storms to cross-shore or

alongshore transport of sediment under wave action

and aeolian deflation and transport. Sediment is thus

retained within an embayment with leakage limited

to offshore areas, into aeolian dunes and in certain

instances into estuaries.

Observations of storm response on high-energy

dissipative shorelines are rare in comparison to

accounts of storm (hurricane and northeaster) impacts

on low energy coasts (e.g., of the eastern United

States). This may be due to the infrequency of

morphologically significant events on high-energy

coasts. On high-energy coasts, the difference in inten-

sity of processes during storms compared to modal

conditions is comparatively less and thus larger

storms might be required to produce morphological

impacts. Guza and Thornton (1982), however, work-

ing in California observed the following relationship

between deep water significant wave height and

significant vertical runup related to dune erosion

during storms:

Rs ¼ 0:71Hs þ 0:035 ð1Þ

Ruggiero et al. (2001) working on dissipative

beaches of the Oregon coast concluded that a combi-

nation of water level and wave runup controlled

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Fig. 3. Schematic plot of shoreline simulation at Magilligan. A shadow zon

is eliminated from the output plots. The output grids for each wave analy

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exposure to storm-induced erosion of dunes.In Ore-

gon where wave energy was substantially higher the

relationship derived for the top 2% of runup was as

follows (Ruggiero et al., 2001):

R2% ¼ 0:5Hs � 0:22 ð2Þ

This equation was regarded as applicable to low-

gradient, dissipative beaches.

It is the objective in this paper to assess the nature

and spatial variability of storm signature, associated

wave conditions and evidence of morphological re-

sponse to storm-induced wave forcing on the high

energy indented coastline of Western Ireland. This is

attempted through analysis of climatic records of

storms, simulation of nearshore wave conditions dur-

ing storms, field observations, and interpretation of

the historical record of storm-induced morphological

response. From this analysis, inferences will be drawn

regarding the nature of coastal response to storms on

such coastlines. The essential characteristics that con-

strain the response of exposed sandy coasts to storm

forcing in this area are as follows:

(a) they contain a fixed sediment volume with no

contemporary sediment supply (there is a long

term sediment deficit)

(b) they are constrained by resistant headlands

(c) they are shaped by refracted swell waves (are

dissipative and exhibit equilibrium plan forms)

(d) they are backed by high, vegetated Holocene

dunes

e of no valid results on the margins of the HISWA computational grid

sis were constructed to lie well within the valid results.

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Fig. 4. Historical shoreline changes at the high water mark at four

exposed dissipative beaches, based on historical maps, air photo-

graphs and contemporary surveys. Data based on shore-normal

advance or retreat compared to initial survey position (1835–1840)

for representative, open coast profiles. Note that the points derived

from historical records do not necessarily imply linear shoreline

change in intervening periods.


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2. Methods

A storm classification and catalogue for western

Irish meteorological stations was presented by Mac-

Clenahan et al. (2001) based on instrumental data

from Malin Head, Belmullet and Valentia (Fig. 1)

spanning the period 1957–1999. This record formed

the basis of comparison of storm signatures at various

sites on the western Irish coast (Fig. 1). Predicted

astronomical tidal conditions during individual storms

were obtained and used to determine coincidence of

onshore storms and high tide at particular sites.

Coastal dynamics during modal (50th percentile)

wave conditions and various combinations of storm-

associated winds were simulated over digitised bathy-

metric charts of selected western Irish coastal sites in

order to investigate the likely impact of storms on the

shoreline. Modelling was undertaken using the pro-

gram HISWA (Booij et al., 1993) and outputs were

presented as 2-D plots of wave energy dissipation,

wave bottom orbital velocity, wave height and wave-

induced stress vectors. For all the simulations default

values were used for model set up. In particular, wave

spread was set to default and a high-resolution com-

putational grid was used to allow maximum flexibility

in wave directional behaviour (resolution in the di-

rectional component was set to 5 degrees). The type of

wave (swell and/or sea) was generated by configuring

the input geometry of the initial deep-water wave field

as indicated by the parametric input wave command

line. Thus, swell waves were produced by long period

initial waves and sea waves by steep short period

ones.

In terms of boundary noise in HISWA, the poten-

tial shadow area lies around 5 degrees of the overall

computational grid, when open boundaries are en-

countered. In all the simulations more than a 5 degree

area was allowed in the computational grid to elimi-

nate invalid sectors of the computational grid from

results. The output plots were thus taken from the

‘‘sound’’ part of the output grid (Fig. 3).

Historical change in several exposed shorelines

with varying orientation (shown in Fig. 1) was de-

duced from available large scale (1:10,000) Ordnance

Survey maps, aerial photography and field topograph-

ical surveys using GPS (Fig. 1). Measurements of

historical changes in shoreline proxies (e.g., mapped

HWM) were made from rectified and geo-referenced

maps, air photos and field surveys and historical

change was plotted for representative sections of the

shoreline at each site (e.g., Fig. 4). In addition, direct

observation of storm impacts on the coastline was

undertaken during the study period and historical

accounts and anecdotal information on storm impacts

were assessed.

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3. Results

3.1. The record of storms in western Ireland

Storms are a relatively frequent and persistent

feature of the climate of western Ireland (Devoy et

al., 2000; Clifford, 2000). A number of major storms

have been recorded in ancient records dating to the

middle ages on account of the damage to human

infrastructure (Burningham, 1998; Burt, 1987; Cooper

and Orford, 1998; Lamb, 1991; Shields and Fitzger-

ald, 1988). Forsythe et al. (2000) examined shipping

losses off the Irish coast and noted that many were

associated with major storms. Despite the long record

of storms, little attention has been given to their

morphological impact at the coast. In part this may

be due to the scarcity of population in rural western

Ireland and a consequent lack of observation of

impacts, and to the lack of infrastructure at risk. In

addition, coastline orphology is attuned to an already

modally high-energy regime and thus storms might

not produce dramatic increases in energy levels at the

shoreline.

The instrumental record of storms in western Ire-

land was studied by MacClenahan et al. (2001) based

on records from the mid 1950 s from Valentia,

Belmullet and Malin Head (Fig. 1). Those authors

compiled a catalogue of storms for each of the three

stations based on several thresholds of wind speed and

duration. During the 45-year period studied, only two

storms were identified at all three stations (albeit by

different wind thresholds) and these were the highest

magnitude events that occurred during the study

interval. Of the two, the largest was a storm that had

originated as Hurricane Debbie (1961) but veered

west across the Atlantic and still maintained hurri-

cane-force winds as it reached the Irish coast (Cooper

and Orford, 1998). This is believed to be the highest

magnitude event in Ireland since a storm in January

1839 known as ‘the Night of the Big Wind’ (Shields

and Fitzgerald, 1988). At all west coast stations, the

1961 storm winds blew from the SW and the highest

gusts recorded were 88 kt at Valentia, 80 kt at

Belmullet and 98 kt at Malin. Peak wind speeds were,

however, sustained at Malin Head for more than 5

h compared to only 2 h at more southerly locations.

The storm coincided with high tide only at Inch–

Rossbeigh and occurred on a falling tide in the

ED PROOF

northerly study areas. Furthermore, the winds were

directed onshore at Inch–Rossbeigh, while on the

north and NW coast they were directed obliquely

offshore.

A further six storms were identified at two of the

three stations but thereafter the three stations (sepa-

rated from each other by only about 200 km along the

same coastline) contained entirely different storm

records. Further variability between stations was ev-

ident in a S–N increase in the number of storms

identified by the same wind thresholds. Storms with

winds over 60 kt were identified only at Malin Head.

Analysis of the frequency of wind events over 25 kt

and persisting for over 5 h at Malin Head and

Belmullet (Burningham, 1998) shows an increase at

both stations over the period 1956–1996 but the most

marked increase is at Malin Head.

The record of storms at each of the sites also

showed some internal variability. At Malin Head all

major (>60 kt) wind events recorded were from the

SW quadrant. In contrast, lower wind speed storms

that persisted for over 48 h all came from directions

between 270j and 90j (i.e., none was from the

southern quadrant). This implies that in NW Ireland

(counties Donegal and Londonderry) soft coastlines

facing SW are exposed to a high energy, short

duration storm regime, while those facing the NE, N

and NW may be more susceptible to lower magnitude,

longer duration storms from those directions.

At Valentia and Belmullet, almost all storms were

associated with a W–SW wind direction and thus soft

coastlines on the west coast facing that direction have

maximum susceptibility to storm effects.

The low angle, dissipative beach profiles that front

exposed west coast beaches appear to be able to

accommodate incident wave energy without net mor-

phological change during most wave conditions.

Trimming of frontal dunes is relatively rare and is

typically associated with storms that occur at or close

to high tide, such that excess wave energy is within

reach of the dune toe.

3.2. Known instances of wave-induced change during

storms

Analysis of historical shoreline positions in north-

ern and western Irish beaches typically show a slow

retreat that is typically ascribed to a slight long-term

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sediment deficit (Carter, 1991) or dispersal into estu-

aries (Burningham and Cooper, 1998). The sparse

nature of the historical record is such that evidence

of the role of storms collectively or individually in

coastal retreat is difficult to determine.

Based upon the historical record of maps and air

photos, varying temporal mesoscale patterns of shore-

line change were recorded at each of the sites inves-

tigated (Fig. 4). It is acknowledged that the wide

spacing of data may also include periods of shoreline

change that have not been recorded by the temporally

incomplete record. The record from four sites is

shown in Fig. 4.

The seaward margin of Magilligan Foreland (Fig.

5) reveals an alternating pattern of erosion and accre-

tion on its open shoreline (Carter, 1975). At Magilli-

gan erosion of nearly 100 m between 1839 and 1850

was followed by accretion up to 1950. Erosion con-

UNCORRECT

Fig. 5. Bathymetry and setting of Magilligan Foreland site. (For locality

channel. The Inishowen Peninsula is composed of resistant bedrock lithol

OOF

tinued until about 1980 and was followed by accretion

since then (Fig. 4). A similar alternation between

erosion and accretion phases was noted at Inch (Fig.

6) where shoreline advance of over 100 m between

1840 and 1910 was followed by a similar magnitude

of erosion up to 1973 (Fig. 4) followed by subsequent

accretion (Orford et al., 1999). The lack of data points

render comparison between the two sites difficult but

point to an oscillating pattern of shoreline change.

Gweebarra and Rossnowlagh (Fig. 7), in contrast,

reveal consistent patterns of erosion and shoreline

retreat. The rate at Rossnowlagh has been almost

constant, whereas Gweebarra appears to have experi-

enced a period of accelerated erosion between 1910

and 1950 (Fig. 4).

The sporadic record of shoreline change coupled

with the relatively short (post-1957) record of coastal

storms renders interpretation of these shoreline

ED PR

see Fig. 1). Note the large triangular ebb-tide delta and deep inlet

ogies. Stippled areas indicate beach and dune sands.

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Fig. 6. Bathymetry and setting of Inch and Rossbeigh sand spits in Dingle Bay. (For locality see Fig. 1). Note the large ebb-delta and gently

sloping embayment. Stippled areas indicate beach and dune sands.

Fig. 7. Bathymetry and setting of Rossnowlagh site. (For locality see Fig. 1). The beach is bounded to the south by Carboniferous limestone

outcrop and to the north by semiconsolidated till cliffs. Stippled areas indicate beach and dune sands.


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UNCORREC

changes in the context of storm history, extremely

difficult. At Inch, Orford et al. (1999) attributed the

two periods of shoreline recession to storm activity,

on the basis of the temporal coincidence of maximum

recorded shoreline recession with the two largest

magnitude storms ever recorded in Ireland; The Night

of the Big Wind of 1839, and Hurricane Debbie 1961.

Analysis of both storms shows that they coincided

with high tide and were directed onshore at Inch. That

they did not coincide with high tide and were directed

obliquely or offshore at the other sites may explain the

lack of apparent impact elsewhere.

The alternating pattern of erosion and accretion at

Magilligan Foreland was attributed by Carter et al.

(1982) to fluctuations in ebb-delta morphology which

mediated wave approach angles. The forcing element

that caused the system to switch from erosion to

accretion was not investigated. It is indeed possible

that individual large magnitude storms were respon-

sible; however, the short temporal record of reliable

climatic data renders interpretation difficult and there

are no historical accounts of specific large-scale

storms to which changes in shoreline behaviour could

be attributed.

While it is tempting to attribute the increase in

erosion rate at Gweebarra to a storm or series of

storms between 1910 and 1950, this predates the

earliest continuous wind record and no anecdotal or

written evidence exists for especially high magnitude

storms that might have been responsible. At Ross-

nowlagh, which has a similar coastal orientation, there

is a less marked acceleration of erosion rate which

may also support a storm-related interpretation.

Again, the paucity of morphological data and short

temporal record of meteorological conditions do not

permit firm attribution of cause and effect.

A number of instances, however, do exist where

direct observations have been made during and im-

mediately after storms on the western Irish coast.

These observations coupled with analysis of storm

wind and tidal conditions provide some insights into

the conditions necessary for coastal response to

storms. Some examples are outlined below.

During a coastal management consultation project

at seven beach/dune systems in County Donegal

(Power et al., 2000), information was sought from

local residents on storm impacts. This revealed a

strikingly small number of storms that did sufficient

ED PROOF

damage to be recalled in the collective memory that

spanned an approximately 50-year period. Two main

events were recalled as follows:

A storm on January 14th 1986 from the northwest

was recalled by residents of Culdaff as the most

damaging in living memory. This storm was recorded

by McKenna (1990) at Portrush and Portstewart

where 7-m-high waves and a 0.8-m surge were

measured. Wind speed during the storm exceeded 30

knots for more than 40 h and 40 knots for 24 h. Three

high tides occurred during the highest intensity of the

storm (Fig. 8). Winds were from the northwest for the

duration of the storm. The storm was three days after

spring tides. On the rocky Portstewart to Portballintrae

coast tideline debris ranged up to 9 m above Ordnance

Datum (approximately equal to low tide). Coarse sand

and gravel were deposited at 5–6 m O.D. by waves.

No damage from this storm was reported from west-

ern sites.

A gale/storm on 9th February 1988 from the SW

that coincided with high tide (Fig. 9) caused a range of

coastal impacts on the NW coast at locations where it

was directed onshore (e.g., Rossnowlagh, Gwee-

barra). This storm did not appear to cause damage

on N and NW-facing coasts and there is no commu-

nity memory of it at such sites. Water levels on the

west coast were reported as the highest in living

memory and a hotel at Rossnowlagh was flooded

with sea water. At Narin, near Gweebarra, a pier

was destroyed by high waves, a seawall was damaged,

and the 5–10 m high dune face was eroded by at least

10 m along its entire length. The beach was stripped

of sand down to an underlying hard, compact sand. At

Rossnowlagh, the dune face was cut back and fine

sand was stripped from the beach leaving an under-

lying coarse gravelly substrate exposed. No dune

erosion was evident on north-facing beaches of Mag-

illigan, Culdaff and Portstewart during this storm.

An account of storm-related dune erosion at

Magilligan Point is provided by Carter and Stone

(1989). From a total of 22 storms that caused erosion

(dune trimming) on Magilligan Point between 1967

and 1983 only three were onshore and could have

caused erosion of dune on the ocean shoreline (9

February 1970, 26 October 1980 and 17 Jan 1982).

Analysis of each of these storm events and compar-

ison with predicted tidal elevations indicates that

they spanned high tide, but these occurred at a range

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Fig. 8. Signature of Jan 14th 1986 storm. Note the persistence of northwesterly winds over a succession of high tides.


UNCof predicted elevations from 2.1 m (spring tide) to

1.4 m (neap tide).

In addition, some direct observations have been

made during the past decade of the impacts of storms

on the NW Irish coast. An onshore gale/storm in

April 1999 at Portstewart (Fig. 1) reached peak wind

speeds of over 25–30 m s-1 (50–60 kts). The peak

of the storm was between 12.00 and 4.00 pm and

wave setup had elevated water levels across the

beach such that the normally dry upper beach was

covered by a few centimetres of water (Cooper and

Jackson, 2001). The storm began to subside as the

tide rose and wind speed had fallen to c. 20 m s-1 by

high tide. No dune erosion took place during the

storm.Similarly, observations on October 9th 1998

during a strong southwesterly storm (Cooper and

Jackson, 1999) indicated that while erosion occurred

along the estuary margin of Magilligan Point, neither

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Fig. 9. Signature of 9th February 1988 storm.


UNCit nor Portstewart strand experienced erosion on the

seaward margin.

These observations provide some insights into

storm occurrence and impact in NW Ireland. The

most striking impression is that despite a high-energy

wind regime, relatively few storms have produced

coastal morphological impacts over a 40–50-year

period. While the instrumental record includes numer-

ous storms only a few are regarded as having pro-

duced coastal damage. Of these, the coastal impacts of

the January 1986 and February 1988 storms have a

distinct geographical focus that is apparently related to

the wind direction. Carter and Stone (1989) despite

regular observations recorded only three impactive

storms on the ocean margin of Magilligan Point

during a 14-year period. Direct observations by the

authors during the past decade found no instance of

dune trimming on the ocean-facing beaches of Mag-

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UNCORREC

illigan, Portstewart or Portrush, despite the occurrence

of both onshore and offshore-directed storms. Despite

being of high magnitude, the onshore storm of April

1999 at Portstewart did not coincide with high tide.

These observations suggest that to be immediately

impactive on dissipative beaches storms need to (a) be

directed onshore, (b) coincide with high tide and (c)

produce wave motions that exceed transport thresh-

olds. These constraints impose a highly localised

pattern of beach responses to the synoptic storm

pattern mediated by the direction in which a beach

faces and the tidal elevation during a storm. Thus,

from a probabilistic perspective, increased duration of

a storm increases its potential impact.

The response (R) of a dissipative beach to a storm

may thus be expressed by the following.

R ¼ f ðT ;Ws;DÞ ð3Þ

Where T = storm duration, Ws = wind speed, and

D = direction. For an erosional response to be experi-

enced, a storm thus needs to occur close to high tide.

Since tidal range varies from 3.5 to 4.5 m along much

of the western seaboard, there is a long tidal interval

during which short-lived storms will not coincide with

such levels. The duration of a storm will thus enhance

its likelihood of spanning a high tide level. The wind

direction appears to be an important constraint on

likely impact as evidenced by direct observations and

suggestions from historical records that onshore winds

are required for measurable change. The wind transfers

energy to waves, which in turn undergo refraction,

reflection and dissipation as they approach the shore.

The threshold at which sediment transport will occur is

therefore site-specific and dependant on wave energy

transformations and sediment textural characteristics.

Consequently, the volume and direction of transport

during storm impacts is likely to be locally variable.

3.3. Storm susceptibility

The storm catalogue for each meteorological sta-

tion was examined to select storms that were onshore

and potentially impactive for Magilligan (Malin

Head), Rossnowlagh (Belmullet) and Inch–Rossbeigh

(Valentia). This indicated a marked reduction from the

number of actual storms to those that were potentially

impactive at these coastal sites. Next, tide predictions

ED PROOF

for each of the storm periods were consulted to

determine which of the storms had occurred at high

tide and were therefore most likely to be recorded in

the historical record of shoreline change. This

revealed a further reduction in the number of poten-

tially damaging storms. Between 1957 and 1998, 10

storms at Rossnowlagh and Gweebarra, eleven at

Magilligan and nine at Inch were onshore, and coin-

cident with high tide. The timing of potentially

impactive storms differs between the meteorological

stations, and further spatial variability is introduced

when the orientation of the coastline is considered.

Carter and Stone (1989), working on Magilligan

Foreland, reported that periods of dune erosion fell

into three categories:

1. extreme onshore winds (>50 kt) coinciding with

high tides

2. strong onshore winds (>25 kt) associated with

extreme tides

3. long period (>12 s) swells coinciding with spring

tides

These observations were from both open coast and

estuarine shorelines and the storms that caused erosion

of dunes were predominantly from the SW, indicating

that they affected the estuarine coast where a dune

scarp is fronted by an intertidal sandflat. Erosion of

dune on the ocean shoreline during onshore winds (0–

90j) between 1969 and 1983 took place during con-

ditions 1 and 2, suggesting that swell waves are less

impactive. Because of a lack of deep-water wave data,

the role of large swells produced by distant storms is

not considered in this paper, although analysis of the

impact of increased swell size using wave modelling

suggests that much of the excess energy is accommo-

dated by development of a wide surf zone with much

wave energy dissipation offshore. In contrast, short

period waves associated with locally strong winds,

dissipate their energy further shoreward, where they

are not fully refracted and may thus be more effective

in generating gradients of wave energy that lead to

alongshore or offshore sediment dispersal.

3.4. Wave simulations

In the absence of comprehensive measurements

and observations during storms, simulations of wave

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action under a variety of modal and storm conditions

were undertaken in order to gain insight into wave

conditions and potential spatial patterns of coastal

response at each of the study sites. A variety of wind

speeds, direction and antecedent wave conditions

were simulated for the study sites. In each simulation,

a bathymetric grid was constructed that extended into

deep water (Fig. 1). Deep-water wave conditions were

then selected as initial input with or without an

accompanying wind field. In the nearshore zone

adjacent to the relevant beaches, a finer model grid

was constructed in which wave output from the initial

coarse grid was used as input parameters. Default

settings were used in the simulations. A selection of

simulations is presented below for Magilligan, Ross-

nowlagh and Inch–Rossbeigh. These were undertak-

en to gain some qualitative insights into the likely

changes in wave hydrodynamics during storm con-

ditions and the input parameters for storms were taken

from meteorological records of likely storm-related

conditions.

3.5. Magilligan

Magilligan Foreland comprises a long NNE-facing

barrier with a smooth concave plan form. It is backed

UNCORRECT

Fig. 10. Simulated vectors of wave-induced stress at Magilligan for (A) m

easterly storm (50 kt winds from the east). Note the change in scale of v

orientation to stress vectors in the surf zone.

ED PROOF

by a low series of dune-topped beach ridges. A tidal

inlet at its western margin separates it from a resistant

rocky headland. A large ebb-delta is located to the SE

of the inlet channel. The shoreline is situated on the

lee side of the Inishowen Peninsula which prevents

the arrival to the shore of large amounts of wave

energy from the SE, SW or NW quadrants. Winds

associated with Hurricane Debbie were offshore in the

Magilligan area.

Simulations of modal wave conditions produce a

marked spatial variation in wave energy at the shore-

line (Fig. 10). The northwestern section of the sea-

ward-facing barrier is located in a wave-sheltered

zone and little swell energy penetrates to the shore-

line. Under modal swell conditions, wave-induced

stress and wave orbital velocities are highest in the

east and on the outer margin of the ebb-tidal delta.

The ocean margin of Magilligan Point is exposed

only to onshore winds from the N–E quadrants and

thus the dominant SW and W storms recorded at

Malin Head are offshore-directed. Easterly storms at

Malin Head tend to be of long duration (MacClena-

han et al., 2001) and thus may span several tidal

cycles. Under strong easterly wind conditions (50

knots) wave simulations indicate a marked change

in wave patterns over modal swell conditions at

odal swell wave conditions and (B) conditions associated with an

ector plots from A to B and the development of a distinct westerly

T

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J.A.G. Cooper et al. / Marine G14

UNCORREC

Magilligan Point. Simulated values of storm wave-

induced stress increase markedly compared to modal

conditions (Fig. 10). Much of the shoreface experi-

ences bottom wave orbital velocities capable of sand

transport and maximum values occur on the highest

sections of the ebb-tidal delta, along the shoreline and

at the apex of Magilligan Point. The normally shel-

tered zone toward the distal section of the point is

subject to a strong surf zone with westerly sediment

transport as indicated by vectors of wave-induced

stress (Fig. 10). The terminus of this transport path-

way is at the apex of Magilligan Point adjacent to the

tidal inlet of Lough Foyle from whence excess

sediment is dispersed by tidal currents.

Historical evidence of shoreline change at Magi-

lligan presented by Carter and Stone (1989) indicates

a progressive erosion of the seaward margin of Mag-

illigan Point between 1949 and 1980 coupled with

progressive extension of the apex by accretion during

the same period. Such a pattern is consistent with

westerly transport of sediment during easterly storms,

with no mechanism for landward return of sediment

under constructional swell waves as the area, is in a

swell wave shadow zone. Between 1956 and 1997, 12

storms (three of which are those recorded by Carter

and Stone, 1989) were onshore (from N–E quadrants)

at Magilligan Point. Several of these lasted for over 24

h and were potentially erosive. Since the area is in a

wave shadow zone and there is no resupply of

sediment by modal swell waves from areas offshore

or to the east, the coastline has receded on the seaward

margin and sediment has accumulated at the apex.

Accumulation at the apex is probably limited by

accommodation space in the tidal inlet (which must

permit passage of the tidal prism) and has been

reported to undergo a quasi-40-year cycle of accumu-

lation and erosion (Carter, 1975). The historic erosion

rates in this section (>3 m/year) are reported as the

highest in Northern Ireland (Carter, 1982a). The site

illustrates the potential role of storms in generating

significant wave energy and sediment transport in a

zone normally sheltered from swell waves by an

adjacent headland (Inishowen) and an ebb-tidal delta.

With a lack of sediment resupply mechanisms, it

appears that storms have dominated shoreline behav-

iour in this section of Magilligan Point, whereas in the

eastern section of the ocean shore, swell waves have

produced little change in shoreline configuration.

ED PROOF

3.6. Rossnowlagh

At Rossnowlagh, a west-facing, dune-backed beach

located between two headlands, modal wave condi-

tions reveal low levels of wave energy and equal

spreading of energy along the coast consistent with a

swash-aligned equilibrium (Fig. 11). A smooth plan

form has resulted between headlands to the north and

south. Results of wave simulations for Rossnowlagh

are shown in Fig. 11. Under modal wave conditions

(Fig. 11A), wave-induced stress values are low and

vectors are directed directly onshore at the shoreline.

The relatively even distribution of energy is controlled

by a shallow offshore zone on which wave shoaling

and energy dissipation is maximised.

Simulation of waves under winds similar to those

associated with Hurricane Debbie or the February

1988 storm (51 knots) indicate both an increase in

magnitude and spatial focussing of wave energy

(Fig. 11B). Wave orbital velocities increase from

south to north with a peak adjacent to the northern

headland and vectors of wave-induced stress suggest

transport of shoreface sediment toward both head-

lands. Shore-parallel stress vectors are particularly

strongly developed at the southern end of the em-

bayment. An additional simulation of background

modal waves with wind-generated waves superim-

posed (Fig. 11C) showed a number of differences.

The effect of superimposition of the two wave fields

was to reduce alongshore variations in the distribu-

tion of wave energy. This is reflected in a near

uniform wave orbital velocity along the beach and

with a pattern of onshore-directed vectors of wave-

induced stress. In addition, the magnitudes of stress

vectors directed toward the headlands are much

reduced and more oblique in angle compared to

the wind-only simulation. The changes are due to

the opposition of the two wave fields which appear

to cause a realignment of energy and suggest that the

modal swell may mask and reduce the morphological

impact of locally generated wind waves. The differ-

ences serve to illustrate the potential control of

antecedent wave conditions on storm impacts with

a 90j change in shoreline wave-induced stress vec-

tors. Given the endless potential combinations of

antecedent conditions and of storm characteristics

and tidal elevation, precise reconstruction of former

storms is likely an untenable goal and approxima-

eology xx (2004) xxx–xxx

UNCORRECTED PROOF

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Fig. 11. Plot so wave-induced stress at Rossnowlagh under (A) modal swell conditions, (B) wind conditions similar to those experienced during

Hurricane Debbie and (C) combined modal swell and storm winds.


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tions of past conditions are the best that can be

expected using this approach.

The patterns of wave-induced stress during storm

conditions do generate a northward drift that could

potentially remove sediment from the embayment

system by transport around the northern headland.

This could be responsible for a gradual reduction in

sediment volume in the embayment that contributes to

the net shoreline recession. Historical shoreline

changes at Rossnowlagh have been significant, and

have involved the progressive erosion and subsequent

rock armouring of the dune, particularly in the south

of the beach. Photographic evidence reveals the loss

of a wide vegetated dune from the southern section of

the beach.

3.7. Inch

At Dingle Bay the funnel-shaped coastline is

bounded by rocky cliffs and two large sandy spits at

the East of the site. Inch peninsula represents the most

dissipative boundary in the system, where isobaths

depict a shallow embayment with contours of gradu-

ally decreasing water depths towards Inch. The mor-

phology of the sea bed appears to exert a strong

influence on the evolution of the depositional features

at Inch. The ebb tidal delta is a prominent shore-

UNCORRECT

Fig. 12. Distribution of wave energy dissipation in Dingle Bay facing the

(B) large swell waves (H6.6m, T, 13.6 s) both from W. Darker shading in

ED PROOF

normal sedimentary feature adjacent to the tidal inlet

between Inch and Rossbeigh. The main exposure of

the embayment is to the southwest.

Under modal swell waves (H 0.4 m; T 7.0 s),

refraction and dissipation within the elongate, gently

sloping bay render energy levels low at the shoreline.

Wave energy dissipation takes place close to shore

with a concentration of energy dissipation midway

along Inch spit (Fig. 12A). Under large swell waves

(H 6.6 m; T 13.6 s) energy dissipation patterns change

with increased dissipation on the distal margin of the

ebb-delta and the northern margin of Inch (Fig. 12B).

Significantly, the distal margins of Inch and Ross-

beigh remain sheltered from the impact of larger

swell.

During modal conditions maximum bottom wave

orbital velocities are concentrated on the southern

(distal) end of Inch and on the shallow sections of

the ebb-tidal delta (Fig. 13A). During high energy

wind conditions similar to those associated with

Hurricane Debbie (44 knots from the southwest, Fig.

13B) the situation remains superficially similar with

much of the incoming wave energy being dissipated

on the frontal margin of the ebb-tidal delta. There is,

however, an increase in nearshore orbital velocities

levels along the northern (proximal) end of Inch and a

zone of elevated wave orbital velocities at the distal

Inch and Rossbeigh sites under (A) modal swell (H0.4m, T 7 s) and

dicates maximum dissipation.

T

ROOF

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Fig. 13. Wave orbital velocities in Dingle Bay associated with (A) modal swell conditions and (B) Hurricane Debbie wind-generated waves.

Darker shading indicates maximum velocities.


UNCORREC

end of the spit adjacent to the inlet channel where

most significant morphological changes have been

observed in the shoreline.

3.8. Discussion: storm events and coastal response

A number of factors constrain the morphological

impact of storms and the identification of their

impacts in western Ireland.

First, because the coastline is exposed to modally

high energy swell that arrives fully refracted at the

shoreline, an increase in swell size may not necessar-

ily create a change in wave energy dispersal (and

hence sediment transport) patterns. Instead, an in-

crease in swell size produces a wider and more

offshore surf zone within which much energy dissi-

pation occurs (Fig. 12). It is, however, also possible

that enhanced wave setup, enhanced secondary flows

and infragravity motions may be enhanced during

large swell waves. Difficulty in elucidating the impact

of such events is constrained by the fact that the

measured wave record is even shorter than the mete-

orological record and by the fact that secondary wave

motions cannot be successfully modelled. Observa-

tions of large swell waves associated with minimal

coastal impact have been made often by the authors.

Second, since the sandy beaches are in the dissi-

pative morphodynamic domain, much long-wave-

ED Plength (swell) wave energy is dissipated across the

shoreface during increased swell regimes and is un-

likely to generate an excess of energy in the near-

shore. At Inch, for example, increased swell size leads

to enhanced offshore dissipation on the ebb-delta and

a wide surf zone.

Third, because the tidal range is relatively large,

the probability of wave set-up during high swell

conditions causing elevated water levels that exceed

normal tidal high water levels is reduced. This is also

true of short period waves.

Under these constraints it is speculated that the

greatest morphological impacts at the shoreline may

result from locally generated, short-period waves

associated with coast-proximal storms. To generate a

response in the shoreline these winds need to be

directed onshore or alongshore and to generate waves

that (a) arrive at the shoreline without being fully

refracted and (b) are sufficiently energetic to transport

sandy sediment. The number of potentially damaging

storms is thus relatively low and is reflected in

anecdotal accounts of storm damage in Donegal.

Analysis of the instrumental record over a 50-year

period reveals a surprisingly small number of poten-

tially damaging storms at individual beach sites.

Indeed, if correctly interpreted, the mesoscale pattern

of coastline behaviour at Inch has been driven by only

two very large magnitude storms over the past 160

T

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UNCORREC

years (Orford et al., 1999). Field observations of

lesser, though still high magnitude storms since

1999 showed no morphological impact at the shore-

line of such storms.

The highly indented western Irish coastline with

beaches facing a number of directions between NE

and S is thus likely to produce a spatially nonuniform

pattern of storm response related to storm intensity,

direction, duration as well as site-specific factors that

mediate wave energy transformations and sedimentary

response. Identification of the impacts is hampered by

a lack of observational data both of coastal response

and of storm occurrence.

A number of outstanding problems preclude the

definition of storm impact on such high energy

compartmentalised beaches. First, the threshold of

storm required to generate morphological change is

not known. This could be investigated by direct

observations and/or detailed wave simulation studies.

It does appear that even though a small number of

recorded storms (c. 10 at each site between 1957 and

1988) coincide with high tide and are onshore

directed, not all of these storms have had erosional

impacts at the shoreline. This is almost certainly

linked to dynamic thresholds at each site and

requires further research to identify the combination

of storm attributes necessary to produce an erosional

response.

Because sediment volumes are largely confined

within embayments, offshore sediment losses during

storms are likely to be replaced by fair-weather swell

conditions. Thus, long-term impacts of storms are

likely to be difficult to detect in the historical record

of morphological change except at the vegetation line

(where growth requires some time to reestablish). The

widely spaced records of storm response may well

mask the impacts of intervening storms if the coastline

has readjusted following storm impacts. Dune scarps

may indeed record the main storms, although these

too are subject to reworking.

If an obliquely directed storm produces a drift

pattern that is sustained for some time (e.g., an

easterly storm at Magilligan), this may redistribute

sediment, steepening the profile and rendering dunes

susceptible to attack by swell waves as the profile

seeks to reestablish itself into a dissipative profile.

Sufficiently, closely spaced observations do not, how-

ever, exist to test this hypothesis.

ED PROOF

Fig. 12 shows wave energy dissipation during

modal swell and extreme swell conditions in Dingle

Bay. During modal swell conditions, energy levels are

low and little dissipation takes place. When wave size

increases, the level of energy increases and a surf zone

develops on the ebb-tidal delta and along the proximal

sections of both Inch and Rossbeigh where swash-

aligned plan forms are present; their distal sections are

sheltered by wave energy dissipation on the ebb-tidal

delta. Not only does the simulation show the control

on plan form by large swell waves, but it illustrates

the ability of such shorelines to accommodate a large

variation in swell wave sizes through energy dissipa-

tion on the shoreface and surf zone without morpho-

logical change. In order to cause a deviation from

swell-related morphology, waves need to arrive at the

shoreline without significant energy losses and/or

produce a different energy dispersal pattern. During

storm conditions a wide spectrum of wave types is

generated but such conditions are more typically

associated with locally generated wind waves that

are of short period and arrive largely unrefracted at

the shoreline.

Two models of storm response on dissipative

beaches are proposed. The first involves an onshore

storm coincident with a near-spring high tide. Under

such storms, dune trimming occurs as small surges

elevate water level and high magnitude winds gener-

ate short-period waves that undermine vegetated dune

margins, causing scarping and erosion and seaward or

alongshore dispersal of eroded sediment. Potential

examples include the erosion at Inch during the

Hurricane Debbie winds of 1961. The second mode

of response involves the occurrence of strong winds

oblique to shore which are sustained during a long

duration storm or a succession of shorter duration

events. Under such conditions, strong alongshore

sediment dispersal takes place that produces localised

reductions in sediment volume. These in turn lead to

steepening of beach profiles and then erosion of the

dune face as the profile reestablishes equilibrium with

high-energy swell waves. This mode can be invoked

to explain the erosion and accretion patterns at Mag-

illigan Foreland, particularly under the influence of

prolonged easterly winds. In such embayed systems,

the role of ebb-deltas as temporary sediment stores

during storms may prove important. Carter et al.

(1982) invoked ebb-delta bathymetry as a control on

TD

R

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REC

shoreline configuration at Magilligan Point and

Orford et al. (1999) similarly alluded to the potential

role of the ebb-tidal delta as a sediment sink in Dingle

Bay.

While strong circumstantial evidence may be pre-

sented for these modes of coastal response on dissi-

pative beaches, field observations are required over

sustained periods in order to investigate further the

temporal evolution of such coasts in response to storm

forcing. In particular, the measurement of nearshore

bathymetry is needed in order to monitor sediment

dispersal and storage.

The results also suggest that areas where modal

wave energy is lowest as swell energy is dissipated,

are particularly susceptible to impacts during storms

when short period waves can reach to the shoreline.

This is well illustrated at Magilligan and the distal end

of Inch where wave sheltering from a rock headland

and ebb-tidal deltas respectively, protect the shoreline

from wave effects during swell conditions. Such areas

may lack a poststorm recovery mechanism as at

Magilligan, or be readjusted during swell-induced

landward transport during fair weather as at Inch.

The paucity of historical data from which shoreline

changes may be deduced hampers definition of shore-

line response to storms. The lack of overwash pro-

motes offshore sediment dispersal and subsequent

landward return which may assist in holding the

shoreline in position, especially given the potentially

large sediment storage in the coastal dune systems that

back many beaches. The dunes to landward, may,

however, preserve a record of storminess. High-reso-

lution chronostratigraphic studies of the preserved

dune sequences may contain historical records of

storminess on such coastlines.
R 965
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968969970971972973974975976

UNCO4. Conclusions

This research sought to elucidate the impacts of

storms at the instantaneous and historical time scales

on a high-energy coast using available data and field

observations. The results presented reveal a number of

constraints on determining storm impact at any scale;

however, a number of conclusions may be drawn.

Field observations and analysis of meteorological

data give the impression of a strong spatial variability

in potential shoreline response to storms. Even if a

OOF

storm is of high enough magnitude to cause morpho-

logical change, factors such as wind direction, coastal

orientation, interaction of wind and swell waves,

produce potentially important differences in coastal

response patterns.

Analysis of the historic shoreline record does not

provide definitive conclusions regarding the role of

storms in coastal evolution. This is partly due to the

long intervals between maps and photos and partly

because of inter-storm reworking.

The difficulty of measurement during storms pla-

ces a strong reliance on pre and post storm morpho-

logical comparisons. For this reason, a baseline of

beach morphology is required against which storm

impacts may be monitored. Wave modelling may help

in the interpretation of morphological changes but

ideally needs to be informed by field observations

of conditions during storms.

P5. Uncited reference

Carter, 1982b

EAcknowledgements

This research was undertaken during a variety of

funded research projects. In particular EC projects

EV5V-CT93-0266 (Impacts), ENV4-CT97-0488

(Storminess) and LIFE LBL464 UK (Participatory

coastal management). Those projects involved several

workers in various institutions and the authors would

like to particularly acknowledge the involvement of

Prof. Julian Orford and coworkers at Queen’s

University, Belfast, at various stages in these projects.

References

Booij, N., Holthuijsen, L.H., Schoonbeek, R., 1993. Standard Tests

for the Shallow Water Wave Model HISWA, Version 100.21.

Dept. of Hydraulic and Geotechnical Engineering, Delft Univer-

sity of Technology.

Burningham, H. 1998. Morphodynamics of west Donegal Estuaries.

Unpubl D.Phil Thesis, University of Ulster.

Burningham, H., Cooper, J.A.G., 1998. Mesoscale evolution of a

west Donegal Estuary. Journal of Coastal Research, Special

Issue 26 (ii), 24–30.

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EC

Burt, S.D., 1987. A newNorth Atlantic low pressure record.Weather

42, 53–56.

Carter, R.W.G., 1975. Recent changes in the coastal geomorpholo-

gy of the Magilligan Foreland, Co. Londonderry. Proceedings of

the Royal Irish Academy 75B, 469–497.

Carter, R.W.G., 1982a. Sea level changes in Northern Ireland. Pro-

ceedings of the Geologists’ Association 93, 7–23.

Carter, R.W.G., 1982b. Recent variations in sea level on the east

and north coasts of Ireland. Proceedings of the Royal Irish

Academy 82B, 177–187.

Carter, R.W.G., 1988. Coastal Environments. Academic Press,

London.

Carter, R.W.G., 1991. Shifting Sands, A study of the coast of

Northern Ireland from Magilligan to Larne. HMSO, Belfast.

Carter, R.W.G., Stone, G., 1989. Mechanisms associated with the

erosion of sand dune cliffs, Magilligan Foreland, Northern Ire-

land. Earth Surface Processes and Landforms 14, 1–10.

Carter, R.W.G., Lowry, P., Stone, G., 1982. Ebb shoal control of

shoreline erosion via wave refraction, Magilligan Point, North-

ern Ireland. Marine Geology 48, M17–M25.

Clifford, L. 2000, The impact of synoptic storm systems on aeolian

sand movements at two coastal sites in County Mayo: Car-

rownisky and Silver Strand. Unpublished MA Thesis, National

University of Ireland (NUIC).

Cooper, J.A.G., Jackson, D.W.T., 1999. Wave spray-induced sand

transport and deposition during a coastal storm, Magilligan

Point, Northern Ireland. Marine Geology 161, 377–383.

Cooper, J.A.G., Jackson, D.W.T., 2001. Surficial beach structures

formed by wave-generated foam. Journal of Geology 109,

780–788.

Cooper, J.A.G., Orford, J.D., 1998. Hurricanes as agents of meso-

scale coastal change in western Britain and Ireland. Journal of

Coastal Research, Special Issue 26, 123–128.

Devoy, R.J.N., Lozano, I., Hickey, K., Nı́ Chaoimh, U., 2000.

Storminess and the modelling of climate change impacts on

environmentally sensitive European Atlantic coasts. In: D.

Smith (ed.), Storminess and Environmentally Sensitive Atlantic

Coastal Areas of the European Union. Final Report. The Coastal

Resources Centre, University College Cork. Commission of the

UNCORR

ED PROOF

European Communities, Research Contract Publication, Con-

tract No. ENV4-CT97-0488, Brussels.

Forsythe, W., Breen, C., Callaghan, C., McConkey, R., 2000. His-

toric storms and shipwrecks in Ireland: a preliminary survey of

severe synoptic conditions as a casual factor in underwater ar-

chaeology. International Journal of Nautical Archaeology 29,

247–259.

Guza, R.T., Thornton, E.B., 1982. Swash oscillations on a natural

beach. Journal of Geophysical Research 87, 483–491.

Lamb, H.H., 1991. Historic Storms of the North Sea, British Isles

and Northwest Europe. Cambridge Univ. Press.

Lozano, I., Devoy, R.J.N., 2000. Storm activity along the Atlantic

coastlines of Europe: a study for the last four decades and a

2xCO2 experiment (ECHAM4 T106). Geophysical Research

Abstracts 2.

Lozano, I., Devoy, R. J. N., May, W., Andersen, U., this volume.

Storminess and associated cyclone tracks along the Atlantic

coastlines of Europe: recent evolution and analysis of an

CO2-induced climate scenario. Marine Geology.

MacClenahan, P., McKenna, J., Cooper, J.A.G., O’Kane, B., 2001.

Identification of highest magnitude coastal storm events over

western Ireland on the basis of wind speed and duration thresh-

olds. International Journal of Climatology 21, 829–842.

McKenna, J. 1990. Morphodynamics and sediments of basalt shore

platforms. Unpubl. D.Phil Thesis, University of Ulster.

Orford, J.D., Cooper, J.A.G., McKenna, J., 1999. Mesoscale tem-

poral changes to foredunes at Inch Spit, south-west Ireland.

Zeitschrift fur Geomorphologie 43, 439–461.

Power, J., McKenna, J., MacLeod, M., Cooper, J.A.G., Convie, G.,

2000. Developing integrated participatory management strate-

gies for Atlantic dune systems in County Donegal, Ireland.

Ambio 29, 143–149.

Ruggiero, P., Komar, P.D., McDougal, W.G., Marra, J.J., Beach,

R.A., 2001. Wave runup, extreme water levels and the erosion

of properties backing beaches. Journal of Coastal Research

17, 407–419.

Shields, L., Fitzgerald, D., 1988. The night of the Big Wind in

Ireland, 6–7 January 1839. Irish Geography 22, 31–43.

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