David Callaghan

Amity Point Flow Slides: overcoming their impacts on infrastructure in a changing climate

For more information, please email dave.callaghan@uq.edu.au

We have been granted ARC (Australian Research Council) funding to investigate the flow slides and the associated erosion hazard at three levels, with likely, formal start around January 2021. It is a three pronged study with study opportunities for at least 3 PhD students. The three prongs of the study are:

1. 2DV investigation of the vertical retreating flow slide (dilative slope failure).
2. The formation and recovery of the erosion embayments, which typically get to a diameter of the order 50m in plan.
3. The longer term, years to decades, development of the shoals in the channel between Nth Stradbroke and Moreton Islands in order to asses worsening versus easing of the erosion threat to the Amity point area at the planning time scale.

1. 2DV Investigation into the vertical retreating sand faces

Vertical retreating sand faces have been observed in nature triggered either by natural processes or dredgers. A number of details are unresolved and worthy of investigation, eg, triggering, development of a vertical face, criteria for maintaining the turbidity current.

2. Intermediate scale investigation

For more information, please email dave.callaghan@uq.edu.au

Flow slide events usually leave a semi-circular indentation of the shoreline with diameter of the order 50m. It is not well understood why this is, ie, why not a more or less straight erosion front between hard boundaries? Similarly, it is surprising that, these ‘erosion bays’ are often filled back in by the natural sediment transport processes in a matter of only a couple of weeks. The ability to prevent or mitigate the erosion events would be of obvious benefit to coastal managers. So, that is the goal of our proposed investigations at these intermediate scales. This investigation will combine monitoring with down-looking cameras, and profile surveying with numerical sediment transport modelling.

3. Large scale morphodynamic modelling

The question: “is the erosion threat at Amity Point going to intensify or ease off over the next decade” is at the centre of this investigation. The answer is tied to the developments of the largescale channels and sandbanks between Amity Point and the southern tip off Moreton island. Hence a numerical hydraulics and sediment transport model is the large scale part of this project.

Moving fish farms offshore into the Southern Ocean: Is it possible?

For more information, please email dave.callaghan@uq.edu.au

There are many pressures on fish farms for moving offshore from pollution through to production. And in Australia, given our location, that means shifting into the Southern Ocean, possibility the most active ocean basin on planet earth and a region with no significant existing installations.

This research aims to estimate wave and fluid motion forcing on a range of fish farming infrastructure to test if there are operational windows and techniques available. This research will occur in parallel with two other projects that focus on the fluid/structure interactions. This research is part of an ARC (Australian Research Council) funded project.

It is expected that successful applicant would also become part of the CRC Blue Economy.

Storm Surge dynamics within the surfzone during cyclonic conditions

For more information, please email dave.callaghan@uq.edu.au

We have been granted ARC (Australian Research Council) funds and have established permanent facilities to measure cross-shore water level (to cm accuracy) using tubes, lasers and cameras. This provides information that allows the unpacking of why observed surges at this site are between two and three times that predicted using current technology. The project would involve three phases, laboratory experiments that mirror the field site, field measurements during either tropical or ex-tropical cyclone conditions or east coast low (usually one major event annually) and analytical extensions to existing numerical models to incorporate the new process understanding.

Wind wave climate estimations under a uncertain future climate

For more information, please email dave.callaghan@uq.edu.au

Queensland, Australia, home of the Great Barrier Reef and beaches, which forms the foundation of the tourism industry, is exposed to annual tropical cyclones. These extreme weather events have a wide range of impacts on this industry from coral and beach damage and flooding. As the climate changes, it is expected that tropical cyclones will also change and that has several authority’s activity working on mitigation and resilience works. These tasks require estimations of wave climates during a changing climate, with significant uncertainties. Consequently, this project seeks to understanding the propagation of uncertainty in wind wave modelling from tropical cyclones that are moving through the Great Barrier Reef.

Spatial and temporal scales of forcing uncertainty, as tropical cyclones move through coastal waters within the GBR, vary significantly. This is qualitatively different to previous work in which spatial scales over which forcing is applied was similar to metrological system applying it. Within the GBR, there are a range of spatial scales at play, from a few kilometres to hundreds of kilometres. Similarly, there are slow- and fast-moving tropical cyclone events, thus varying the temporal scale. This project will unpack those influences and develop approaches to include them efficiently when estimating wave climates generally. Those approaches will be tested on the Great Barrier Reef as an exemplar.