CRC REEF RESEARCH CENTRE TECHNICAL REPORT No. 33

Great Barrier Reef Depth and Elevation Model: GBRDEM.

Adam Lewis, James Cook University

EXECUTIVE SUMMARY

Bathymetry is fundamental to the marine environment. A knowledge of ocean floor topography is essential for informed and sustainable marine resource management. It is also vital to scientific understanding of the physical and biological marine environments which are strongly linked to depth.

We have produced a bathymetry - a 'depth model' - of the Great Barrier Reef as a research and management tool. Working from extensive experience with terrain models on land, we have used the best data and processes we believe to exist. More importantly, we have established a process so that the bathymetry can continue to improve as new data are added.

The model allows us to visualise, either as pictures or as graphs, the structure of the Great Barrier Reef to improve our qualitative and quantitative understanding of the region. In the far north, the 'lagoon' is shallow, with a complex bottom topography and a steep continental slope. In the south, the outer reefs are hundreds of kilometres from shore and the waters are deep, the bottom topography varies from smooth in the lagoon to extremely complex toward the outermost reefs, and the continental slope is gentle. The model shows large areas of submerged reef which are not visible from the air, and therefore, do not appear on other maps. These areas alone may have important implications for resource management.

The depth model depends on data: depth soundings, and parts of the Great Barrier Reef are notoriously poorly mapped. In areas like the Swains, commitment to bathymetric survey work is essential if the picture is to improve. Technology such as the LASER Airborne Depth Sounder (LADS) can map reef areas to depths of approximately 30 metres.

Research and other vessels also have an important role to play. In stark contrast to the situation two hundred years ago, thousands of vessel hours yield little data on depth. Continuous real-time data logging of position and depth, by only a few research vessels, would lead to great improvements with minimal cost.

Our depth model is available to all managers and scientists within the CRC Reef Research Centre Ltd. Given a low level of funding for technical support, it will be maintained and improved through the new CRC.

THIS PUBLICATION IS CITED AS:
Lewis, A. (2001)
Great Barrier Reef Depth and Elevation Model: GBRDEM.
CRC Reef Research Centre Ltd
Technical Report No. 33.
Townsville; CRC Reef Research Centre Ltd, 58 pp.

ISBN 1 876054 64 6

A full copy of this report may be obtained from the author(s), and through the following libraries: