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Aeolian sediment transport under offshore winds is usually discounted from sediment budget considerations of coastal dunes. Results presented here indicate however, that depending on wind orientation and foredune morphology, positive contributions to the sediment budget can arise from offshore winds. Lee-side airflow patterns, seaward of the foredune crest, under offshore winds were studied at three sites of varying foredune geometry along Magilligan Strand, Northern Ireland. Ultrasonic anemometers recorded 1 Hz wind velocity data at 1° intervals. Descriptive statistics and wind rose diagrams were used in the analysis of these data. Under perpendicularly offshore winds each site exhibited a different type of lee-side airflow pattern. A tall (11·4 m), sharp-crested foredune produced flow separation with a recirculation cell. A lower (6·6 m), more rounded, foredune crest exhibited lee-side flow that remained attached but was deflected parallel to the crest, while flow over a low incipient foredune crest resulted in attached flow with no deflection in the lee. The morphology of the lee slopes best explained these airflow adjustments. More obliquely offshore winds were also found to affect the secondary airflow patterns, with a smooth transition from flow separation to flow attachment as the incident angle decreased. At higher wind velocities this smooth transition was replaced with a more abrupt switch between the secondary airflow types. This threshold was located at similar approach angles to those recorded for desert dunes (90° +/− 20°). These findings have significant implications for the post-storm recovery and long-term evolution of beach-dune systems where the predominant winds are offshore, and offer an explanation for the presence of many beach-dune systems in lee-coast locations. Copyright © 2010 John Wiley & Sons, Ltd.

The equilibrium planform concept (EPC) for bayed beaches has achieved wide currency in coastal morphodynamics. The north coast of Ireland comprises a series of discrete headland-embayment beaches within which waves and currents recycle a finite sediment volume. It is therefore an ideal setting in which to explore the applicability of the concept. Application of the approach to 9 embayment beaches on the north coast of Ireland provides some insights into the application of the concept. The planform of some beaches does correspond to that predicted while others do not. Those whose measured planform does not correspond to the predicted planform can be interpreted through, (a) difficulty in identifying the wave diffraction point, (b) disequilibrium on the beach (sediment scarcity or excess), (c) geological control of beach morphology. The subjectivity in selecting the diffraction point renders alternative explanations difficult and reduces the utility of the approach on natural shorelines, where significant irregularities render identification of such points difficult.

There are more than 15,000 barrier islands in fetch-limited nearshore environments around the world. About half that number are actively evolving (eroding, accreting, migrating) in response to oceanographic processes and are the subject of this study. The remaining half consists of inactive islands protected by surrounding salt marsh or mangroves. Despite their global abundance these islands have not been previously systematically studied or even recognized as a major landform type. More than 70% of fetch-limited barrier islands are found on trailing edge coasts because conditions there are favorable for formation of sheltered waters. Fully 50% are found in the coastal zone of Australia, Mexico, and Russia. We identify eight different types of fetch-limited barrier islands based on genesis and mode of occurrence. Most of the active islands form in estuaries or bays (Spencer Gulf Australia), behind open ocean barrier islands (Pamlico Sound, North Carolina), or on flood tidal deltas of open ocean t...

A 2-year investigation into shoreface morphodynamic behaviour off a high-energy headland-embayment coast in Northern Ireland reveals important process–response mechanisms that cannot be explained solely by existing conceptual models. Fourteen sequential bathymetric surveys, conducted every 1–2 months, show that morphologic (seabed) change is not directly related to oceanographic forcing—extensive nearshore and shoreface accretion and erosion occurs under fair-weather, modal and high-energy conditions. The main factors which seem to cause significant change are long-duration (swell) events coupled with onshore winds, availability of (recently) introduced sediment, surges and elapsed time between storms and the next scheduled survey. Several high-energy events over a short time period ( −2 of shoreface accretion from the nearshore to 24 m depth. Net erosion was not observed anywhere, including the subaerial beach. Geologic evidence strongly suggests that the source of the significant volume (7.7×105 m 3 ) of sediment introduced into the study area must have been derived from the lower shoreface and/or inner shelf, beyond 24 m depth.

Experiments carried out at Magilligan Strand on the north coast of Ireland suggest that topographic steering of offshore winds is an important facet of the aeolian sediment transport system at this location. A five-day study (18-22 June 2005) investigated the pattern of airflow over the foredune while simultaneously collecting data on sediment flux. A simple instrument setup was used to characterise the airflow: a sonic anemometer was placed at the dune crest, with another on the mid-beach. Horizontal traps, electronic and integrating, measured sediment flux on the supra-tidal beach. Results show that offshore wind flow deviated from its original direction in the lee of the dune (seaward of foredune). The change in direction was not a simple steering of flow to a singular new direction, but rather flow separation resulting in turbulent multidirectional flow - including reversal. Traps located at the foot of the dune scarp recorded sediment transport during events forced by offshore winds. Data from sediment traps, wind and observational evidence have been used to argue that sedimentation was occurring in this zone. When budgeting for sediment movement within beach-dune systems it is important to take into account the effect of secondary airflow patterns during offshore winds and their role in constructive processes of foredune formation, particularly in post-storm recovery. (C) 2008 Elsevier B.V. All rights reserved.

The European Recommendation on Integrated Coastal Zone Management has six core principles. These form two groups, one concerned with strategic goals and one that has a local focus. The principles are presented as a menu of free-standing options, with no prioritization either within or between groups. In the case of coastal erosion management these characteristics result in irreconcilable conflicts, and actively hinder sustainable management of eroding coasts. The principles require clarification, and recognition that they are an indivisible integrated set which should not be used to select principles to advance a particular agenda. It is essential that the strategic principles are given priority, because only they can underpin a sustainable approach to the issue of coastal erosion.

Unsuccessful attempts to use process-scale models to predict long-term aeolian sediment transport patterns have long been a feature of aeolian research. It has been proposed that one approach to overcome these problems is to identify micro-scale variables that are important at longer timescales. This paper assesses the contribution of two system variables (secondary airflow patterns and fetch distance) to medium-term (months to years) dune development. The micro-scale importance of these variables had been established during previous work at the site (Magilligan Strand, Northern Ireland). Three methods were employed. First, sand drift potentials were calculated using 2 years of regional wind data and a sediment transport model. Second, wind data and large trench traps (2 m length x 1 m width x 1.5 m depth) were used to assess the actual sediment transport patterns over a 2-month period. Third, a remote-sensing technique for the identification of fetch distance, a saltation impact sensor (Safire) and wind data were utilized to gauge, qualitatively, sediment transport patterns over a 1-month period. Secondary airflow effects were found to play a major role in the sediment flux patterns at these timescales, with measured and predicted rates matching closely during the trench trap study. The results suggest that fetch distance is an unimportant variable at this site. Copyright (C) 2007 John Wiley & Sons, Ltd.

The Mgeni Estuary is situated on the subtropical, mainly microtidal Natal coast. Modern sedimentary environments in the estuary comprise two groups. Barrier-associated environments include inlet channel, inlet beachface, tidal delta, washover fans, transverse intertidal bars and aeolian dunes. Estuarine environments include subtidal channels, interidal bars, back-barrier lagoon, tidal creek, tidal creek side-attached bars, creek mouth bar, mangrove fringe and supratidal mudflats. Each sedimentary facies is described in terms of grain-size, sedimentary structures, and sedimentary processes. The distinctive flora and fauna play an important role in facies recognition. Vertical sequences produced by infilling of the estuary and subsequent coastal erosion are discussed. The facies are considered sufficiently distinct to warrant recognition in the geological record.

Evolution of sand spits along the Caribbean coast of Colombia: natural and human influences.- Patterns of sand spit development and their management implications on deltaic, drift-aligned coasts: the cases of the Senegal and Volta River delta spits, West Africa.- El Paramo Transgressive Gravel Spit, Tierra Del Fuego, Argentina.- Gravel spit-inlet dynamics: Orford Spit, UK.- Aeolian sand invasion: georadar signatures from the Curonian Spit dunes, Lithuania.- The joint history of Troia peninsula and Sado ebb-delta.- The Historical Evolution of the Tindari-Marinello Spit (Italy - Sicily).- Anthropogenic influence on Spit Dynamics at Various Timescales: Case Studie in the Bay of Cadiz (Spain).- The Development and Management of the Dingle Bay Spit-Barriers of Southwest Ireland.- Polish spits and barriers.- Tidal Flat-Barrier Spit Interactions in a Fetch-Limited, Macro-Tidal Embayment, Lubec, Maine, USA.- Sandy spits and their mathematical modeling.- Spits on the French Atlantic and Channel coasts: morphological behaviour and present management policies.- The sand spits of the Rhone River delta: formation, dynamics, sediment budgets and management.- Long-, mid- and short-term evolution of coastal gravel spits of Brittany, France.- Morphological characterization and evolution of Tahadart littoral spit, Atlantic coast of Morocco.- Geomorphology and internal sedimentary structure of a landward migrating barrier spit (Southern Sylt/ German Bight): Insights from GPR surveys.- Morphology and the Cyclic Evolution of Danube Delta Spits.

This paper describes a new method for assessing aeolian fetch distances in beach/dune systems. The remote-sensing technique has advantages over currently used proxy measures of fetch distance, such as those based on tide gauges and beach profiles. The method uses a digital camera, global positioning system surveying, and a geographical information system software package to produce a rectified image of the beach surface. From this, direct measurements of the wet-dry beach boundary can be combined with wind direction measurements to determine fetch distance. The method offers an improvement on current approaches to sediment transport estimates: a 28-day study on Magilligan Strand, Northern Ireland, showed that the commonly used high water mark approach overestimated fetch distance by 30% compared with the technique reported here.

New seismic stratigraphic, vibracore and AMS C-14 dates from two sites off the Northern Ireland coast yield information on the deglacial to present sea-level history and shelf evolution of the region. A lowstand of sea level at about 30 m below present sea level recorded by fossils in a lowstand shoreline deposit occurred around 13.4 cal ka B.P. following a period of rapid isostatic uplift associated with a RSL fall of 6-7 cm/yr. Following the lowstand, contrasting styles of sedimentation characterized the two study sites. In the sheltered environment of Belfast Lough, the lowstand shoreline was overtopped and buried by transgressive facies of intertidal and shallow sub-tidal mud and sandy mud. On the high-energy Portrush coast, the inner shelf sedimentary sequence is characterized by a basal conglomerate overlain by well-sorted sands with occasional interbedded gravel. (c) 2006 Elsevier B.V. All rights reserved.

In the face of a global rise in sea level, understanding the response of the shoreline to changes in sea level is a critical scientific goal to inform policy makers and managers. A body of scientific information exists that illustrates both the complexity of the linkages between sea-level rise and shoreline response, and the comparative lack of understanding of these linkages. In spite of the lack of understanding, many appraisals have been undertaken that employ a concept known as the “Bruun Rule”. This is a simple two-dimensional model of shoreline response to rising sea level. The model has seen near global application since its original formulation in 1954. The concept provided an advance in understanding of the coastal system at the time of its first publication. It has, however, been superseded by numerous subsequent findings and is now invalid. Several assumptions behind the Bruun Rule are known to be false and nowhere has the Bruun Rule been adequately proven; on the contrary several studies disprove it in the field. No universally applicable model of shoreline retreat under sea-level rise has yet been developed. Despite this, the Bruun Rule is in widespread contemporary use at a global scale both as a management tool and as a scientific concept. The persistence of this concept beyond its original assumption base is attributed to the following factors: 1. Appeal of a simple, easy to use analytical model that is in widespread use. 2. Difficulty of determining the relative validity of ‘proofs’ and ‘disproofs’. 3. Ease of application. 4. Positive advocacy by some scientists. 5. Application by other scientists without critical appraisal. 6. The simple numerical expression of the model. 7. Lack of easy alternatives. The Bruun Rule has no power for predicting shoreline behaviour under rising sea level and should be abandoned. It is a concept whose time has passed. The belief by policy makers that it offers a prediction of future shoreline position may well have stifled much-needed research into the coastal response to sea-level rise.

Despite acknowledgement by scientists and modelers of the shortcomings of mathematical models of beach behaviour, they continue in widespread use for engineering design and environmental impact studies. In part, this is because of the assumed absence of a viable alternative approach to prediction. The objective of this paper is to suggest that a conceptual approach can succeed as an alternative to mathematical models for predictions with accuracy ranges useful for engineering and coastal management purposes. The most valuable information for prediction is past engineering experience on the beach in question or the experience on neighboring beaches. The next most useful may be the global experience on oceanographically similar beaches. Another approach is the use of geoindicators and field studies on the beach. The widely applied “predict nothing” approach to beach engineering may well work if fortified by common sense. Finally, a composite approach in which the assembled body of information on a ...

Two barrier island systems from southern Mozambique (Inhaca and Bazaruto) are described. Both systems comprise a composite barrier island or barrier island chain that developed on a steep continental margin as a result of initial (Pleistocene) spit progradation. Continuing aeolian dune deposition against this initial core during subsequent sea-level highstands and lowstands has given rise to the highest dunes (120m) of any known barrier island. Wave reworking of the composite barrier island sediment during the past 6000 years of the Holocene sea-level highstand has resulted in the formation of spits, barriers, barrier islands and bluffs on the downdrift and bay side sections of the barrier island systems. The relative stability in position of the barrier systems at contemporary sea level is attributed to their large sediment volume and the development of equilibrium shoreline forms under swell waves. Beachrock and aeolianite outcrops provide anchor points for the development of contemporary shore...

The role of statutory designations to regulate activities is an important element in coastal zone management in Europe. In this paper we assess the utility of one such designation the “Area of Outstanding Natural Beauty” as a tool for coastal management in Northern Ireland. The designation is based on landscape quality and offers the potential for an integrated approach. However a variety of weaknesses reduce their effectiveness. Several suggestions are offered to improve the utility of this designation.

The methods used to determine or predict volumes of sand transported by longshore currents are briefly reviewed. We argue that the methods are flawed and that a fundamental re-examination of both field and theoretical approaches is in order. Net transport numbers obtained by any existing method should be considered order-of-magnitude values at best that are in no case sufficiently precise for coastal engineering purposes such as prediction of beach nourishment costs and environmental impacts.

Methodological aspects of GPS (Global Positioning System) and Total Station (Electronic Distance Measurement) surveying techniques were examined as part of a beach monitoring programme which was used to assess morphological variation of a high-energy beach system at Runkerry, Co.Antrim, Northern Ireland. The accuracy of the instruments as well as data processing methods concerning data conversion in different plane coordinates systems is discussed. GPS with Real Time Kinematics (RTK) provides high-resolution control on topographical surveying within limits on the order of centimeter-level accuracy in the horizontal and 2 cm in vertical dimension. Total station (EDM) also demonstrated high accuracy during its use in the monitoring programme. The model of EDM used in this work had a 5 to 6 degrees offset angle for the orientation due to the inherent characteristics of the instrument. A threshold-narrowed point selecting treatment was used to form a beach profile point set for the profile plot and any further processing. This work demonstrates that a two-dimensional translation and rotation for horizontal dimension data conversion is preferable over linear regression method; while the linear regression method for the vertical dimension data is still acceptable. It is suggested therefore that when a conversion of beach surveying data from one plane coordinate system to another is required, then this combined approach should be adopted in the analysis.

A Late Quaternary sea-level curve for South Africa is presented on the basis of new and published data from a range of sea level indicators and a variety of locations. Available evidence suggests that sea level in South Africa broadly follows that described from the Caribbean but that deviations occur during sea-level highstands. During the last interglaciation (oxygen isotope stage 5) and the late Holocene, coastal emergence produced higher sea levels in South Africa than those identified in the Caribbean during the same time intervals. This is tentatively ascribed to predicted lithospheric deformation in continental margin settings.

The success of any coastal zone management policy is dependent on, among other things, effective legislation and its enforcement. This article examines some possible legal constraints on the implementation of an integrated coastal zone management policy in Ireland. An introduction to the existing legal framework is provided, and the inconsistencies and ambiguities related, in particular, to jurisdiction and area of responsibility are highlighted. In particular the effect of land ownership and property rights on coastal zone management are examined with reference to two popular resort beaches in County Donegal, Ireland. While a revision of the relevant legislation is desirable, it is probably unrealistic; however, powers are available to the various institutions involved in coastal management that are currently unused. These are reviewed and their potential to improve coastal zone management is discussed.

A variety of patented approaches have been devised in efforts to halt shoreline erosion. Commonly termed ‘alternative’ or ‘innovative’ technologies, these are typically variations on the traditional approaches. A categorization of these approaches is presented that identifies devices placed in the water and devices placed on the beach. These categories are further subdivided. Despite their innovative nature and the claims of their inventors and promoters, these devices suffer from a variety of weaknesses when deployed in the real world. We present a non-exhaustive list of 110 devices for which US patents were awarded since 1970.

Coastal zone management is often hampered by ineffective collection of multidisciplinary information and, even when adequate data is available, ineffectual transfer of information from scientist to end-user. This may result in either poor or non-reproducible data collection procedures or sub-optimal utilisation of information, which ultimately impact on the quality of coastal zone management decisions. In this paper the authors outline an approach to the acquisition and effective transfer of integrated, multidisciplinary, environmental information from scientist to end-user. The Estuarine Health Index (EHI) was developed by focusing process research on physical, chemical and biological aspects of estuaries with an additional aesthetic component, into an integrated measure of estuarine health. The results may be portrayed either as a series of simple icons on a map, or as a stacked bar chart for a section of the coast and thus convey multidisciplinary information easily. In this paper the development of the individual components of this index is briefly described and the use of the index is illustrated by reference to results collected on over fifty estuaries on the South African coast. Finally, management uses of this approach and some of its benefits in terms of temporal and spatial environmental assessment are outlined.

Along the southwestern coast of Portugal, a high-energy, swelldominated environment with a markedly seasonal wave climate, morphologicchange in three embayed beaches was regularly monitored over a two year period.While a general seasonal pattern was identified, the occurrence of a storm groupinduced dramatic beach response, producing marked interannual variability.Significant spatial variations in behaviour emerged during the monitoring period,inducing alongshore non-uniform beach change within each embayment. Megaripswere the prevailing mechanism responsible for the extreme erosion experienced inall three beaches, and their specific location (controlled by topography) contributesto the variability observed within each beach. Despite severe beach erosion, duneswere unaffected, which suggests long-term stability of these high-energy,dissipative, embayed coastlines.Introduction

Beachrock is present in many parts of the world, particularly on low-latitude coastlines. Its formation during stillstands or minor regressions in subtropical areas involves cementation of clastic grains and thus prevents grain transport in the littoral zone during later transgression or regression. Existing short and medium-term conceptual and numerical models of coastal evolution fail to take into account this effective reduction of littoral sand supply and the effects of the beachrock itself on shoreline development. In the short term, reduction of sediment supply through beachrock formation during transgression should enhance landward translation of the shoreline: conversely the beachrock itself may afford a degree of protection from erosion. In the medium to long term, beach-rock formation during multiple Pleistocene transgressions and regressions in areas which lack significant sediment input from land drainage systems may have caused a long-term reduction in sediment volume during the course of the Pleistocene. (This assumes that beachrock formation is not matched by its destruction through physical and bioerosion and chemical weathering.) Preservation of coastal facies is greatly enhanced by beachrock formation which may promote overstepping and drowning of strandline facies during transgression or preferential preservation during regression. Precise records of sea-level fluctuations may be preserved by beachrock formation, a situation rendered almost impossible in other areas due to littoral transport of mobile sediment. In the widespread areas in low latitudes where it occurs, beachrock formation may be an important element in models of horizontal shoreline displacement and coastal evolution.

In exposures of Pleistocene rocks on the east coast of South Africa, eight sedimentary facies were distinguished on the basis of petrology, grain size, internal structures and field relationships. These are interpreted as deposits of surf zone, breaker zone, swash zone, backbeach, boulder beach and dune environments. Three phases of deposition and diagenesis are recognized. As a result of the stabilising effect of pre-existing coastal facies, the deposits from successive sea level stands are stacked vertically in a narrow coast-normal strip. Early cementation prevented erosion of the deposits during subsequent transgressions. Deposition of subsequent facies took place on an existing coastal dune (Facies 1). A terrace was cut into this dune at a sea level 4.5 to 5 m above present. At this sea level, clastic shoreline sediments were deposited which make up the main sedimentary sequence exposed (Facies 2-7). The steep swash zone, coarse grain size, and comparison with modern conditions in the study area indicate clastic deposition on a high-energy, wave-dominated, microtidal coastline. Vertical stacking of progressively shallower water facies indicates progradation associated with slightly regressive conditions, prior to stranding of the succession above sea level. During a subsequent transgression to 5.5 or 6 m above present sea level, a second terrace was cut across the existing facies, which by then were partly lithified. A boulder beach (Facies 8) deposited on this terrace is indicative of high wave energy and a rocky coastline, formed by existing cemented coastal facies. Comparison with dated deposits from other parts of the South African coast suggest a Late Pleistocene age for Facies 2-8. Deposition was terminated by subsequent regression and continuing low sea levels during the remainder of the Pleistocene. Cementation of the facies took place almost entirely by carbonate precipitation. The presence of isopachous fibrous cements suggests early cementation of Facies 1, 2, 3 and 4 under marine conditions, initially as aragonite which has since inverted to calcite. Facies 5, 6 and 7 are cemented only by equant calcite spar, evidence of cementation in the meteoric phreatic and vadose zones. Lowering of the water table during regression caused the remaining pore space in Facies 1, 2, 3 and 4 to be filled with equant calcite spar. Decementation in a 130 cm wide zone is attributed to water table shifts associated with the later transgression which deposited Facies 8. The vertical stacking of the two depositional sequences may be attributed to rapid cementation of Facies 2, 3, 4, 5, 6 and 7 under humid, subtropical conditions. This lithified sequence then acted as a focus for deposition of coarse-grained shoreline facies (Facies 8) during the subsequent transgression.

A mental map of the substrate of Lough Neagh, Northern Ireland, compiled from interviews with local fishermen, is compared with maps produced by science-based techniques. The comparison reveals that the mental map is highly accurate. This finding contrasts with the spatial distortion characteristic of the classic mental map. The accuracy of the Lough Neagh map is attributed to the fact that it is a compendium of the knowledge of several generations, rather than an individual perception. Individual distortions are filtered out, and accuracy is promoted by economic self-interest. High accuracy may be characteristic of the mental maps held by artisanal exploiters of natural resources.

The Mgeni Estuary is situated on the east coast of South Africa. Tidal salinity changes commonly extend 2.5 km upstream from the mouth. The subtropical climatic regime causes seasonal flooding, the geomorphological effects of which are increased by a steep river gradient. A 120-150 year flood event during September 1987, with an estimated peak discharge of 10800 cumecs, resulted in the erosion of 1.86 × 106 m3 of sediment from the estuary. The normal high tide volume of the estuary (0.35 × 106 m3) increased to 1.85 × 106 m3 after the flood. The post-flood intertidal volume (tidal prism) of the estuary was 0.43 × 106 m3 compared to 0.19 × 106 m3 before the event. The nature and extent of erosion in the estuary was controlled by the composition of the estuary banks and bed material. Gravel and sand substrates were preferentially eroded from the estuary bed before the cohesive bank materials were undercut in sections of the estuary. Mud and fine sand were deposited on overbank areas when the flood waned and a lag of coarse sand and gravel was produced on the estuary bed. Approximately 46 per cent of the bedload sediment supplied to the estuary since 1917 was retained in the estuary until the 1987 flood. The remainder was transported through the system and into the Indian Ocean. Results show that catastrophic floods play an important role in sedimentation in small estuaries.