ORCID Profile
0000-0002-8948-4579
Current Organisations
University of Western Australia
,
Federal University of Technology
,
Rufus Giwa Polytechnic
,
University of Tasmania
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Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2020JC017010
Abstract: Coral reefs generate substantial volumes of carbonate sediment, which is redistributed throughout the reef‐lagoon system. However, there is little understanding of the specific processes that transport this sediment produced on the outer portions of coral reefs throughout a reef‐lagoon system. Furthermore, the separate contributions of currents, sea‐swell waves, and infragravity waves to transport, which are all strongly influenced by the presence of a reef, is not fully understood. Here, we show that in reef‐lagoon systems most suspended sediment is transported close to the seabed and can, at times, be suspended higher in the water column during oscillatory flow transitions (i.e., near slack flow) at sea‐swell wave frequencies, and during the peak onshore oscillatory velocity phase at infragravity wave frequencies. While these wave frequencies contribute to the transport of suspended sediment offshore and onshore, respectively, the net flux is small. Mean currents are the primary transport mechanism and responsible for almost 2 orders of magnitude more suspended‐sediment flux than sea‐swell and infragravity waves. Whilst waves may not be the primary mechanism for the transport of sediment, our results suggest they are an important driver of sediment suspension from the seabed, as well as contributing to the partitioning of sediment grain sizes from the reef to the shoreline. As the ocean wave climate changes, sea level rises, and the composition of reef benthic communities change, the relative importance of mean currents, sea‐swell waves, and infragravity waves is likely to change, and this will affect how sediment is redistributed throughout reef‐lagoon systems.
Publisher: American Geophysical Union (AGU)
Date: 02-2017
DOI: 10.1002/2016JC011755
Publisher: Public Library of Science (PLoS)
Date: 18-01-2023
DOI: 10.1371/JOURNAL.PONE.0279623
Abstract: Flow velocities within coral reefs are greatly reduced relative to those at the water surface. The in-reef flow controls key processes that flush heat, cycle nutrients and transport sediment from the reef to adjacent beaches, all key considerations in assessments of reef resilience and restoration interventions. An analytical framework is proposed and tested with a suite of high-resolution numerical experiments. We demonstrate a single parameter that describes the total coral frontal area explains variation of horizontally averaged velocity within a reef canopy across morphologies, densities, and flow depths. With the integration of existing data of coral cover and geometry, this framework is a practical step towards the prediction of near-bed flows in erse reef environments.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-02-2018
Abstract: If coral reefs continue to degrade, waves on coastlines may substantially increase, leading to greater coastal erosion.
Publisher: Wiley
Date: 27-12-2022
DOI: 10.1111/EMR.12541
Abstract: The role of recreational fishers forming paths (routes of concentrated passage characterised by short vegetation or ground indentation) as they gain access to wilderness waterbodies has not been well documented in Australia. Recreational use for trout and tournament fly fishing has increased in the Central Plateau of Tasmania therefore, it is important to determine the human contribution to path formation and its potential consequences for bio ersity conservation in this area of high conservation value. We predicted that paths parallel to waterbodies experienced more human traffic than orthogonal paths. Across 36 sites at different distances from roads, a parallel and orthogonal path to lakeshore were s led using eight, 1 × 1 m quadrats randomly located along each path within a 10 × 10‐m plot. Recorded for each quadrat were the path widths, height difference between centre of paths and adjacent vegetation (path depth), vegetation types on and adjacent to paths, Bennetts Wallaby ( Notamacropus rufogriseus ) and Wombat ( Vombatus ursinus ) faecal numbers. General linear models indicated that path width was greater on parallel than orthogonal paths and declined with distance from roads. Path depth, however, was not affected by distance from roads but was shallower than orthogonal paths. Separate models used to test the potential effects of edge vegetation type, or the covariates Wallaby and Wombat scats did not have significant effects on‐path variables. Paths encircling or orthogonal to Central Plateau lakes appear different floristically to adjacent vegetation communities, nonetheless. Heath and tussock grassland were largely absent from paths, whereas grassland and herbfield communities were infrequently observed off paths. Herbfield and grassland are rarer communities than heath and tussock grassland, which, in the context of a lack of exposure to erosion, suggests a conservation benefit of paths at present usage levels. The human contribution to parallel path conditions is likely to be high, given the results from the study, so monitoring of change is desirable, especially if predicted increasing human activity eventuates in this area.
Publisher: American Geophysical Union (AGU)
Date: 11-2022
DOI: 10.1029/2022JC018857
Abstract: Wave breaking on the steep fore‐reef slopes of shallow fringing reefs can be effective at dissipating incident sea‐swell waves prior to reaching reef shorelines. However, wave setup and free infragravity waves generated during the sea‐swell breaking process are often the largest contributors to wave‐driven water levels (wave runup) at the shoreline. Laboratory flume experiments and a two‐dimensional vertical phase‐resolving nonhydrostatic wave‐flow model, which includes a canopy model to predict drag forces generated by roughness elements, were used to investigate wave‐driven water levels for along‐shore uniform fringing reefs. In contrast to many previous studies, both the laboratory experiment and the numerical model account for the effects of large bottom roughness. The numerical model reproduced the observations of the wave transformation and runup over both smooth and rough reef profiles. The numerical model was then extended to quantify the influence of reef geometry and compared to simulations of plane beaches lacking a reef. For a fixed offshore forcing condition, the fore‐reef slope controlled wave runup on reef‐fronted beaches, whereas the beach slope controlled wave runup on plane beaches. As a result, the coastal protection utility of reefs is dependent on these slopes. For our ex les, with a fore‐reef slope of 1/5 and a 500 m prototype reef flat length, a beach slope of ∼1/30 marked the transition between the reef providing runup reduction for steeper beach slopes and enhancing wave runup for milder slopes. Roughness coverage, spacing, dimensions, and drag coefficient were investigated, with results indicating the greatest runup reductions were due to tall roughness elements on the reef flat.
Publisher: Wiley
Date: 05-2018
DOI: 10.1002/2017JF004468
No related grants have been discovered for Andrew Pomeroy.