Project Leader and Host Organisation

Dr Richard Brinkman, Australian Institute of Marine Science

Project Description and Objectives

For detailed descriptions of the outputs for this project for Year 4 (2009/2010) of the MTSRF Research Programme, see the Annual Research Plan.

An extension task to Project 2.5i.1 is working to reveal the underwater landscape of the northern Australian seabed by developing a new and detailed 3D seabed map [Read more]

Hydrodynamic models simulate the advection and mixing of water - processes fundamental in controlling the fate and impact of freshwater, sediment, nutrients and pesticides delivered from catchments in to the receiving waters of the Great Barrier Reef (GBR) lagoon. We believe the modeling community is currently in a position where it is feasible to develop a whole-of-GBR hydrodynamic model that includes all of the important factors affecting currents, mixing, temperature and salinity within the GBR lagoon and exchanges with the adjacent Coral Sea.

This project aims to develop a three-dimensional whole-of-GBR baroclinic hydrodynamic model (GBR model) at a spatial resolution of approximately 1-2 km, with accurate boundary forcing for offshore ocean boundaries provided by a global, data-assimilating, eddy-resolving model.  Such a model will underpin the future development of other essential components of a Large-Scale Water Quality (LSWQ) model, primarily sediment dynamics and biogeochemical models, and provide a capability to support the prediction and analysis of connectivity and exchange of material, including larvae, throughout the GBR.

At this spatial resolution of ~1-2 km, a critical challenge will be to deal with the range of spatial scales encountered within the model domain, in particular the need to resolve effects of reefs and reef passages at scales of less than the model resolution. In order to meet this challenge, an important part of this project will involve an investigation and assessment of the necessity and suitability of sub-grid parameterisation schemes within a model of this spatial resolution.

As a proof of concept for a full, three-dimensional hydrodynamic model of the GBR, we will use the model developed in this project to hindcast the circulation within the GBR lagoon during the 2009 wet season, including prediction of the trajectories and spatial distribution of major freshwater inflows during this period.

Key objectives of this project are to:

• Develop a three-dimensional whole-of-GBR baroclinic hydrodynamic model, at a resolution capable of capturing the key oceanographic processes impacting the GBR. This model is a necessary precursor to the development of sediment dynamics and biogeochemical components of a whole-of-GBR Water Quality Model;

• Demonstrate proof of concept of a whole-of-GBR model through the simulation of the circulation within the GBR lagoon during a significant wet season, including prediction of the trajectories and spatial distribution of major freshwater inflows during this period; and

• Assess the suitability of sub-grid parameterisation schemes appropriate for application within finite difference models GBR model.

High-resolution depth model for the Great Barrier Reef and Coral Sea

Project 2.5i.1 extension project
Led by Dr Robin Beaman, James Cook University
Visit Deep Reef Explorer website

Project Description and Objectives

There is a critical lack of information about the location and spatial extent of deep-water ecosystems and seabed habitats for about a third of the Great Barrier Reef World Heritage Area (GBRWHA) lying deeper than two hundred metres. In addition, most of the inter-reefal seabed shallower than two hundred metres on the GBR shelf, and in fact many of the 2,000+ coral reefs themselves, have never been adequately mapped with modern echosounder techniques. Therefore key seabed geomorphic features, such as shoal habitats and submerged reefs, which help define the spatial boundaries of deepwater ecosystems remain largely hidden from view and outside of effective management. However, in recent years there has been a vast increase in the amount of depth data obtained in the GBR through a series of research vessel mapping expeditions. Combined with the latest satellite remote sensing depth data and light detection and ranging (LiDAR) results, this extension project will develop a new high-resolution depth model for the GBR and adjoining Coral Sea (see graphic).

The spatial data tools and information provided by the project will improve vital knowledge required for informing managers of the GBRWHA. For example, managers require data on where the key physiographic features in the deep GBR are. The managers also require knowledge on how well the current zoning network protects these seabed features and their associated biodiversity. In addition, marine scientists require accurate and detailed depth data for targeting seabed biodiversity sites and for planning future research locations.

The project will determine the relief and spatial distribution of key seafloor features through the development of a regional ~100m resolution digital elevation model (DEM), plus traditional contour maps and shaded-relief images of the undersea landscape, or seascape. The mapping outputs of the extension project will also contribute to the concurrent e-Atlas project to provide a web-delivered visualisation of the 3D seascape of the GBRWHA.