Ian Eliot

Bio: Ian Eliot is an academic researcher from University of Western Australia. The author has contributed to research in topics: Sediment transport & Shore. The author has an hindex of 22, co-authored 63 publications receiving 1527 citations. Previous affiliations of Ian Eliot include University of Wollongong.

Impact of sea-breeze activity on nearshore and foreshore processes in southwestern Australia

Abstract: In coastal regions sheltered from the direct impact of swell- and storm-wave activity, locally generated wind waves, particularly those associated with strong sea-breeze activity, play a dominant role in controlling nearshore and foreshore processes. Field data collected from the Perth Metropolitan Coast (western Australia) during a typical summer sea-breeze cycle, are presented. It is demonstrated that the nearshore environment responds rapidly to an increase in wind speed (up to 12 m s −1 ) during the sea breeze, resulting in considerable changes to the nearshore hydrodynamics and morphology. Incident wave energy increased during the sea breeze and was associated with development of a wind-wave field with significant wave heights up to 0.9 m. Nearshore currents responded to this change in wave climate with the development of net offshore near-bed currents and a rapid increase in the mean longshore current from −1 to 1.0 m s −1 A 10-fold increase in suspended sediment concentration and a 100-fold increase in the longshore sand transport resulted from the effects of the sea-breeze system. Erosion of the beachface was coincident with the development of the wind-wave field. Sea breeze wave-driven water circulation also completely eroded beach cusps (wavelength 20–30 m), overwhelmed the rip current system associated with the beach cusps and suppressed the infra-gravity wave frequencies in the incident wave and swash record. The beach cusps reformed after the cessation of the sea breeze. It is demonstrated that the beachface is in a constant stage of adjustment to the incident wave energy through the diurnal sea-breeze cycle alternating between dissipative and reflective morphodynamic regimes. The results may be used to determine the impact of a medium-sized storm on the beachface. It is clear that the sea-breeze system plays a major role in controlling the nearshore and foreshore processes not only in this region, but also on other geographic locations where strong sea breezes are present.

Sheltered sandy beaches of southwestern Australia

Abstract: Morphodynamic classifications of sandy beaches have been established for open-ocean, wave-dominated environments. However, many natural sandy beaches exist in embayments, or are landward of protective reefs, where they are sheltered from the full effects of ocean waves. It is therefore appropriate to question whether such low-energy beaches can be related to conceptual models of beach hierarchies, and to examine whether they have identifiable morphodynamic signatures. Surveys were conducted of the nearshore morphology and dynamics on over fifty beaches on the microtidal coast of Southwestern Australia, between Cape Arid on the South and Geraldton on the West Coast. In most instances, surveys were conducted on beaches that were sheltered by their aspect and/or the presence of offshore reefs. The remaining surveys were conducted on wave-dominated beaches in order to provide a link to the existing morphodynamic models. Descriptions of beach morphology, determined from the surveys, were subjected to a cluster analysis to establish groupings of similar morphologic types. This analysis provided a six-fold classification of beach morphologies and indicated a clear separation between the low- and high-energy beach morphologies on the basis of the overall scalp of the nearshore profiles. Four low-energy morphotypes were distinguished. These are essentially planar and characterized by the absence of either nearshore bars or other rhythmic features. However, the low-energy morphotypes may be discriminated by variations in beach slope and curvature. Canonical variate analysis was conducted to examine the discrimination of the six morphotypes on the basis of their sedimentary and dynamic characteristics. This analysis indicated consistent sedimentologic differences between the morphotypes, despite moderate overlapping between several of the beach forms. The variation accords with expectations that flatter beaches tend to have finer sediments. Discrimination between the morphotypes on the basis of their dynamic variables was less revealing. This raises questions of misfitting between form and process during the surveys and may indicate the importance of storm events in the formation of these low-energy morphotypes.

Predicted climate change, sea-level rise and wetland management in the Australian wet-dry tropics

Abstract: The vulnerability of coastal areas in the Alligator Rivers Region (northern Australia) to predicted climate change and potential sea level rise was assessed as part of a national study The coastal area is composed of a number of estuarine and freshwater habitats that are intricately interlinked and can not be effectively managed in isolation of each other The outcomes of the assessment focused on the floodplain environments of the region, but are also applicable to the broader wetland environments that occur across the northern Australian wet-dry tropics The management regime in the region is based on traditional Aboriginal ownership of much of the land, which is leased to the federal government as a national park Scientific research has been intensive; however, important questions have been raised about the collation and effective use of this information The vulnerability assessment framework required effective use of this information and cooperation with the management authority to identify change scenarios and management and research responses A climate change scenario was established as the basis for predicting biophysical change in the coastal and wetland environments The predictions suggest that large-scale change will occur and many of the existing values derived from these areas (ie, usage by traditional Aboriginal occupants, and nature conservation) could be degraded or even lost Recommended management responses include the initiation of specific monitoring, empowerment of local bodies to take active management steps, and to increase awareness of the likely consequences of change Further data coordination and review are needed to ascertain the validity of the predictions and the concomitant management responses

Climate Change 2007: Impacts, Adaptation and Vulnerability.

Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

Coastal systems and low-lying areas

Abstract: Since the IPCC Third Assessment Report (TAR), our understanding of the implications of climate change for coastal systems and low-lying areas (henceforth referred to as ‘coasts’) has increased substantially and six important policy-relevant messages have emerged. Coasts are experiencing the adverse consequences of hazards related to climate and sea level (very high confidence). Coasts are highly vulnerable to extreme events, such as storms, which impose substantial costs on coastal societies [6.2.1, 6.2.2, 6.5.2]. Annually, about 120 million people are exposed to tropical cyclone hazards, which killed 250,000 people from 1980 to 2000 [6.5.2]. Through the 20th century, global rise of sea level contributed to increased coastal inundation, erosion and ecosystem losses, but with considerable local and regional variation due to other factors [6.2.5, 6.4.1]. Late 20th century effects of rising temperature include loss of sea ice, thawing of permafrost and associated coastal retreat, and more frequent coral bleaching and mortality [6.2.5]. Coasts will be exposed to increasing risks, including coastal erosion, over coming decades due to climate change and sea-level rise (very high confidence). Anticipated climate-related changes include: an accelerated rise in sea level of up to 0.6 m or more by 2100; a further rise in sea surface temperatures by up to 3°C; an intensification of tropical and extratropical cyclones; larger extreme waves and storm surges; altered precipitation/run-off; and ocean acidification [6.3.2]. These phenomena will vary considerably at regional and local scales, but the impacts are virtually certain to be overwhelmingly negative [6.4, 6.5.3].

Shoreline Definition and Detection: A Review

Abstract: BOAK, E.H. and TURNER, I.L., 2005. Shoreline Definition and Detection: A Review. Journal of Coastal Research, 21(4), 688‐703. West Palm Beach (Florida), ISSN 0749-0208. Analysis of shoreline variability and shoreline erosion-accretion trends is fundamental to a broad range of investigations undertaken by coastal scientists, coastal engineers, and coastal managers. Though strictly defined as the intersection of water and land surfaces, for practical purposes, the dynamic nature of this boundary and its dependence on the temporal and spatial scale at which it is being considered results in the use of a range of shoreline indicators. These proxies are generally one of two types: either a feature that is visibly discernible in coastal imagery (e.g., highwater line [HWL]) or the intersection of a tidal datum with the coastal profile (e.g., mean high water [MHW]). Recently, a third category of shoreline indicator has begun to be reported in the literature, based on the application of imageprocessing techniques to extract proxy shoreline features from digital coastal images that are not necessarily visible to the human eye. Potential data sources for shoreline investigation include historical photographs, coastal maps and charts, aerial photography, beach surveys, in situ geographic positioning system shorelines, and a range of digital elevation or image data derived from remote sensing platforms. The identification of a ‘‘shoreline’’ involves two stages: the first requires the selection and definition of a shoreline indicator feature, and the second is the detection of the chosen shoreline feature within the available data source. To date, the most common shoreline detection technique has been subjective visual interpretation. Recent photogrammetry, topographic data collection, and digital image-processing techniques now make it possible for the coastal investigator to use objective shoreline detection methods. The remaining challenge is to improve the quantitative and process-based understanding of these shoreline indicator features and their spatial relationship relative to the physical land‐water boundary.

Climate change and Australia: Trends, projections and impacts

Abstract: This review summarizes recent research in Australia on: (i) climate and geophysical trends over the last few decades; (ii) projections for climate change in the 21st century; (iii) predicted impacts from modelling studies on particular ecosystems and native species; and (iv) ecological effects that have apparently occurred as a response to recent warming. Consistent with global trends, Australia has warmed ~ 0.8 � C over the last century with minimum temperatures warming faster than maxima. There have been significant regional trends in rainfall with the northern, eastern and southern parts of the continent receiving greater rainfall and the western region receiving less. Higher rainfall has been associated with an increase in the number of rain days and heavy rainfall events. Sea surface temperatures on the Great Barrier Reef have increased and are associated with an increase in the frequency and severity of coral bleaching and mortality. Sea level rises in Australia have been regionally variable, and considerably less than the global average. Snow cover and duration have declined significantly at some sites in the Snowy Mountains. CSIRO projections for future climatic changes indicate increases in annual average temperatures of 0.4-2.0 � C by 2030 (relative to 1990) and 1.0-6.0 � C by 2070. Considerable uncertainty remains as to future changes in rainfall, El Nino Southern Oscillation events and tropical cyclone activity. Overall increases in potential evaporation over much of the continent are predicted as well as continued reductions in the extent and duration of snow cover. Future changes in temperature and rainfall are predicted to have significant impacts on most vegetation types that have been modelled to date, although the interactive effect of continuing increases in atmospheric CO 2 has not been incorporated into most modelling studies. Elevated CO 2 will most likely mitigate some of the impacts of climate change by reducing water stress. Future impacts on particular ecosystems include increased forest growth, alterations in competitive regimes between C3 and C4 grasses, increasing encroachment of woody shrubs into arid and semiarid rangelands, continued incursion of mangrove communities into freshwater wetlands, increasing frequency of coral bleaching, and establishment of woody species at increasingly higher elevations in the alpine zone. Modelling of potential impacts on specific Australian taxa using bioclimatic analysis programs such as BIOCLIM consistently predicts contraction and/or fragmentation of species' current ranges. The bioclimates of some species of plants and vertebrates are predicted to disappear entirely with as little as 0.5-1.0 � C of warming. Australia lacks the long-term datasets and tradition of phenological monitoring that have allowed the detection of climate-change-related trends in the Northern Hemisphere. Long-term changes in Australian vegetation can be mostly attributed to alterations in fire regimes, clearing and grazing, but some trends, such as encroachment of rainforest into eucalypt woodlands, and establishment of trees in subalpine meadows probably have a climatic component. Shifts in species distributions toward the south (bats, birds), upward in elevation (alpine mammals) or along changing rainfall contours (birds, semiarid reptiles), have recently been documented and offer circumstantial evidence that temperature and rainfall trends are already affecting geographic ranges. Future research directions suggested include giving more emphasis to the study of climatic impacts and understanding the factors that control species distributions, incorporating the effects of elevated CO 2 into climatic modelling for vegetation and selecting suitable species as indicators of climate-induced change.