John McKenna

Socio-economic data in coastal vulnerability indices: constraints and opportunities

ABSTRACT Most previously developed coastal vulnerability/sensitivity indices acknowledge that the addition of socio-economic variables would assist in defining vulnerable areas. This study investigated the incorporation of socio-economic variables into a GIS based coastal vulnerability index for wave-induced erosion in Northern Ireland. In this application, a socio-economic sub-index was developed to contribute potentially one third of the overall index score; the other components consisted of coastal forcing and coastal characteristic sub-indices. All variables were ranked on an arbitrary 1–5 scale with 5 being most vulnerable. The variables were merged within sub-indices and then the sub-indices were combined to produce the overall index. Several problems were encountered in assessing socio-economic vulnerability indicators. These relate to the inherent difficulties involved in ranking socio-economic data on an interval scale. Temporal aspects also caused difficulties as socio-economic variables vary over time as coastal populations and policies change. There were also problems in relation to the size of the unit used to display the data and how this affected the vulnerability of certain areas. Larger, more fundamental, problems in relation to human perceptions of vulnerability were also investigated. The final results of the combined index were tested against field and desk-top studies and although they correlated well with expected outcomes, the results did suggest an under representation of the socio-economic index. Suggestions are put forward to alleviate this problem in any future developments.

Mesoscale coastal behavior related to morphological self-adjustment

High-energy events (extratropical storms, tsunamis, and hurricanes), sediment supply variability, and sea-level rise are regarded as major drivers of coastal geomorphic behavior. In this paper we document a 170 yr record of cyclic coastal changes that occur independently of such external drivers. In a geologically constrained situation with no external sediment input, two end-member morphological configurations (attractors) are identified between which the system alternates. Although neither configuration is stable, the system as a whole exhibits century-scale equilibrium. Our findings present a hitherto unreported form of decadal scale self-adjustment in a coastal system that has occurred under a stable sea level with a consistent wave and tidal regime.

Sea-level, sediment supply and coastal changes: Examples from the coast of Ireland

Abstract Sediment supply and pre-existing shoreline morphology are crucial factors in controlling coastal changes due to sea-level rise. Using examples from both southeast and northeast Ireland, it can be shown that sea-level change may trigger a sequence of events which leads to both static and dynamic shoreline equilibrium. Cliff erosion and longshore sediment movement in east Co. Wexford has led to injection of sediment onto the shelf, and the growth, under both wave and tide regimes, of linear offshore shoals. These shoals now control the pattern of shoreline erosion and provide a template for possible stepwise evolution of the coast under any future sea-level rise. In contrast, the nearby coast of south Co. Wexford comprises a series of coarse clastic barriers moving monotonously onshore, via overwash processes. Here the behavior of the barrier is conditioned by the antecedent morphology of both the beach face and stream outlet bedforms. Finally, the rock platform coast of Co. Antrim presents a far more resistant shoreline to incident marine processes, yet even here there is strong evidence of present process control over so-called ‘raised’ platforms and embayments. It is concluded that coastal sediment supply and dynamics, together with coastal morphology and its interaction with waves, present a far more complex variety of sea-level indicators than is normally acknowledged.

Accurate Mental Maps as an Aspect of Local Ecological Knowledge (LEK): a Case Study from Lough Neagh, Northern Ireland

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.

A 200-year record of gale frequency, Edinburgh, Scotland: possible link with high-magnitude volcanic eruptions

Most research concerned with the relationship between volcanic activity and global climate change has focused on the impacts that volcanoes have on atmospheric temperature. Very little attention, however, has been given to the effect of volcanic eruptions on patterns of storminess. Here we present a historical record of gale-day frequency for Edinburgh, Scotland, extending from AD 1780 to 1988 (the Mossman-Hickey chronology), which we believe represents the longest historical record of gales in Europe. Calculation of gale- day frequency for this time interval shows three clear peaks in storminess that follow the volcanic eruptions of Tambora (1815), Krakatoa (1883) and El Chichon (1982). It appears that the greatest periods of storminess evident in the Edinburgh record during the last 200 years have taken place during relatively short intervals following major episodes of volcanism. If correct, the processes linking high-magnitude volcanic eruptions to storminess in the North Atlantic need to be included in IPCC research that presently focuses most attention on linkages between increased storminess and the effects of global warming.

Inner shelf seismic stratigraphy off the north coast of Northern Ireland: new data on the depth of the Holocene lowstand

New seismic stratigraphic data are presented from the inner shelf off the north coast of Northern Ireland. The sequence preserved comprises an acoustic basement of till or solid bedrock, overlain by a fine-grained, acoustically transparent unit interpreted as glacio-marine sediment. This is overlain by an upper, reflective sandy unit which contains a discontinuous but widespread internal reflector, interpreted as peat that developed during a late glacial/Holocene relative sea-level fall and continued to accumulate until; subsequent inundation. The depth of the Holocene lowstand is estimated at -30 in MSL on the basis of the seaward extent of the sandy unit and its intercalated peaty horizons, the presence of erosional notches and a widespread break in slope at this depth. The lowstand is not definitively dated but on the basis of dated deposits in adjacent locations is inferred to have occurred between 10 000 and 11000 14C yr BP

The relationship between the rate of mesoscale sea-level rise and the rate of retreat of swash-aligned gravel-dominated barriers

Abstract In theory, a rise in sea level should force swash-aligned gravel-barriers to retreat landwards. Evidence from three single-crested, swash-aligned gravel barriers from eastern Canada and northwest Europe indicates that barrier-retreat rate correlates with the rate of sea-level rise measured over the lower end of the mesoscale time spectrum (subdecadal: 10 0 yr–10 1 yr). There is also a relationship between a barriers rate of change in retreat rate and the decadal mesoscale mean rate of sea-level rise (specified by the duration of the tide-gauge record: 10 1 yr–10 2 yr). Specifically, the higher the decadal mesoscale sea-level rise rate the faster the rate of retreat of the swash-aligned gravel barrier. However, this latter relationship may also be a function of the barriers inertia as defined by the barriers cross-sectional volume in that barrier retreat rate correlates negatively with barrier inertia.

Boom and Bust: The Influence of Macroscale Economics on the World's Coasts

The recent and ongoing global economic crisis and its im mediately preceding boom have had profound impacts on coastlines worldwide They provide some insights regarding the influence of macroscale economics on coastal sustamabil lty, and here we explore the implications for coasts and the communities that use them We conclude that the economic boom has had disastrous consequences for coastal sustam ability worldwide One of the major lessons from this period of rampant development is that current coastal management is not up to the task

Developing Integrated Participatory Management Strategies for Atlantic Dune Systems in County Donegal, Northwest Ireland

Abstract Development planning and resource management in the Irish coastal zone have traditionally followed sectoral, top-down models, with limited opportunities for public participation or concertation of administrative effort. Integrated Coastal Zone Management (ICZM) is often proposed as an appropriate policy response in cases where these approaches have been seen to fail. In this paper, we argue that ICZM may be more sustainable if first introduced at a small scale. Local-level initiatives, designed to produce demonstrable benefits at an early stage, are perhaps more likely to engender long-term support for ICZM. This is particularly relevant where baseline data are lacking and coastal processes are poorly understood. Using seven county Donegal beach and dune systems as demonstration sites, the potential of this approach to provide scientifically-founded, locally-agreed management plans was tested over a range of coastal issues, such as progressive shoreline erosion, habitat loss, tourist development, conflicting recreational activities and traffic management. Progress at each of the sites was partially dependent on the existence, coherence and activity of existing community organizations. In the best example, a local development group already employing many of the central principles of ICZM (e.g. inclusive participation, working with natural processes) was identified. By focussing on local problems, practical solutions and relatively small numbers of stakeholders, agreement was reached on the majority of issues and strategies covered by the management plans. Implementation of the plans will begin in early 2000.

Coast Erosion in Northeast Ireland:-Part II Cliffs and Shore Platforms

This paper summarises the erosion of the ‘hard’ coast (cliffs and shore platforms) of northeast Ireland, between Portstewart, Co. Londonderry and Larne. Co. Antrim. Although there is abundant evidence of localised coastal changes, it is not possible to define rates of erosion except on the glacial material cliffs at Portballintrae. where a mean rate of 0.25m/year (1949- 1987) was recorded, although this mean rate appears anomalous in a longer term perspective. Elsewhere, marine erosion is confined to occasional block falls or block dislodgement. Undercutting of cliffs also helps to trigger a variety of sub-aerial slope failures ranging from small superficial slides to large landslips. Patterns of marine erosion are linked to lithological variations in the rock, with the most resistant material (Cretaceous chalk) showing no discernible changes over the last 100 years. The construction of the Antrim Coast Road (A2) in the 1800s has led to the disruption of littoral sediment supplies along stretches of the e...