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Jolimont, Australia

We combined sediment and faunal data to explore the role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities at Broken Bank and Swarte Bank, in the southern North Sea. A variety of sediment transport processes occur in the area, differing in the frequency and magnitude of sediment mobility, and the continuum between erosion, translation and sediment accumulation. The seabed contained a variety of bedforms, including longitudinal furrows, and small to very large sandwaves. The bed sediments were dominated by fine and medium sands, with admixtures of silt and gravel. Based on sedimentary bedforms and grain size analysis, a total of 11 sedimentary facies were delineated, of which 8 were analysed in detail for their relationships with the meiofauna. The sedimentary facies fell clearly into groups of facies, respectively representing high, high-moderate and moderate, and episodic sediment mobility. For those sedimentary facies where daily movement of sediments and bedforms occurred ('high' sediment mobility), the resulting spatially homogeneous environments were dominated by an impoverished nematode community comprising small deposit feeders and large predators. Resistance to sediment movement and the ability to exploit alternative food sources were prominent functional features of the successful colonisers. Those facies characterised by relatively infrequent sediment mobility ('episodic' and 'high-moderate and moderate' sediment mobility) comprised a heterogeneous suite of benthic habitats, containing taxonomically and functionally diverse assemblages of nematodes of various sizes, feeding types and reproductive potential. Faunal distribution patterns here indicated trade-offs between the resistance to sediment movement, environmental tolerance and competitive abilities. Our focus on diverse assemblages of organisms with high turnover times, inhabiting highly dynamic sedimentary environments, has revealed new animal-sediment relationships of relevance to pure and applied science. © 2014 Schratzberger, Larcombe. Source

Courtney J.,Bureau of Meteorology | Buchan S.,RPS MetOcean | Cerveny R.S.,Arizona State University | Bessemoulin P.,Meteo - France | And 5 more authors.
Australian Meteorological and Oceanographic Journal

This paper details the event, recording instrumentation, and verification of a new world extreme three-second average wind gust record of 113.3 m s-1, measured on Barrow Island, Australia, during the passage of tropical cyclone Olivia in April 1996, and the public and media reaction to that verification. This record supersedes the previous extreme of 103.3 m s-1 measured at the Mount Washington Observatory in New Hampshire, USA, in April 1934. Members of a World Meteorological Organization evaluation committee critically reviewed the data of the Olivia event, determined the Barrow Island wind measurement was valid and established the record. With the announcement of the record, interesting public reaction has occurred and is discussed, as well as the concept of more detailed classification of wind extremes. Although Olivia now holds the record for having the highest wind gust ever measured, this record doesn't imply that Olivia is the most intense cyclone recorded. However, planners should be aware that extreme gusts well above the 'typical' gusts quoted on the intensity scale are possible for tropical cyclones, particularly for category 4 and 5 tropical cyclones. Source

Fandry C.,RPS MetOcean | Shimizu K.,Max Planck Institute for Meteorology
Coasts and Ports 2013

The proposed Gunns Pulp Mill was one of the most controversial projects in Australia because of the potential environmental risks posed by the discharge of some 64 million litres per day of effluent into Bass Strait at a site some 3 km offshore. A very comprehensive 12 month measurement and hydrodynamic modelling study demonstrated that the concentration levels of effluent in the waters and sediments were within the very strict environmental levels set by the Commonwealth and Tasmanian Governments. This study was unique in that it followed earlier studies that were found to be deficient in a number of areas by an expert panel established by the Office of the Chief Scientist of Australia and reporting to the Federal Environment Minister. RPS MetOcean was invited by Gunns to design and undertake a new study that addressed the deficiencies identified by the expert panel. Every aspect from its initial scope to the detailed scientific results and the final reports were scrutinized by the expert panel to ensure that the study was being undertaken at the highest scientific level and that the conclusions were scientifically defensible. The paper will emphasize the importance of applying state-of-the-art modelling by experienced scientists or engineers in combination with the collection of a very detailed set of measurements undertaken by experienced field personnel. Measurements were required for the calibration of wave and current models (to be used in the sediment transport simulations), and for the validation of the circulation and sediment transport models. Measurements were undertaken at 3 sites over a 12 month period and included sea-level, waves, current profiles, sediment particle size distribution and settling velocities (for TSS), turbidity, temperature and salinity. All were measured using state-of-the-art instrumentation including Acoustic Wave And Current (AWAC) meters, single level current meters (RPS MetOcean built CMO4), LISST-100x and LISST-ST, YSI-SONDEs, and Seabird CT loggers and CTDs. All of this work is reported in 7 reports of over 600 pages and is available at http://www.gunnspulpmill.com.au/permits/epbc.php. This paper is a very condensed version of these reports and focuses only on the hydrodynamic circulation modelling. While the main objective of the study was to determine whether the concentration levels of key contaminants in Bass Strait were within acceptable environmental levels, the aim in this paper is to present results of the calibration and validation of the hydrodynamic model against measured currents, temperature and salinity. Source

Larcombe P.,RPS MetOcean | Huang P.,RPS MetOcean | Pusey G.M.,RPS MetOcean | O'Leary M.,Curtin University Australia
Scour and Erosion - Proceedings of the 7th International Conference on Scour and Erosion, ICSE 2014

Sand transport was measured in the shallow subtidal zone of a macrotidal, seasonally waveinfluenced tropical setting, at Broome, northwest Australia, to inform the design of a proposed boating facility. For five weeks, waves and currents were measured in the subtidal zone, with LISST-100x and LISST-STx instruments measuring in-situ particle size distributions (PSD) and settling velocities of mobilized sediment. Boat-based vertical profiles taken on the faster and longer ebb tide revealed very strong vertical gradients in PSD (sand concentrations in the basal 40 cm of 20-30 times that 1 m above bed and higher) and indicated some variation potentially due to the turbulent bursting process. The LISST in-situ particle size data was invaluable in understanding the sedimentary processes, assessing the uncertainties and lending weight to the conclusions. The potential long-term rate of sand flux was calculated to be ∼200,000 m3/yr towards the SSW, which, even taking the uncertainties into account, was likely to prove unmanageable in practical terms. © 2015 Taylor & Francis Group, London. Source

Ward I.,University of Western Australia | Larcombe P.,RPS MetOcean | Mulvaney K.,340 Elliot Cres. | Fandry C.,RPS MetOcean
Quaternary International

The islands of the Dampier Archipelago preserve a probable 30,000 year archaeological record that reflects the change from a continental to an island environment following post-glacial sea-level rise. The geomorphological history of the Dampier Archipelago region in combination with preliminary hydrodynamic modelling of past tidal regimes provides the basis for a new model of how the shelf landscape may have developed between the Last Glacial Maximum (c. 20kaBP), through the Holocene marine transgression and up to the present day. Using first-order geomorphological principles, an assessment is made of the key Late Pleistocene and Holocene sediment bodies that may preserve archaeological deposits.We show that archaeology is most likely to be present in deposits associated with the early phases of inundation of the Dampier Archipelago, dating from around 9-7kaBP. At this time relative sea levels were around -30m to -15m, which was when coastal configuration was complex and the variety and scale of intertidal and shallow sub-tidal environments wide. In contrast, we anticipate that coastal archaeology older than ~12kaBP, when the post-glacial sea levels were below ~50m, will have been exposed to a phase of faster tidal currents on the continental shelf, and hence eroded or poorly preserved. Our study aims to improve prospection for and later management of the as yet-unknown submerged elements of West Australia's rich archaeological heritage. © 2013 Elsevier Ltd and INQUA. Source

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