World's first 3D map of the Great Barrier Reef

How do you map 135,000 square miles of coral reef that has defied every previous attempt to survey it - an area of natural beauty and significance so fragile that any sea expedition would inevitably damage it beyond repair?

For researchers from the University of Queensland and James Cook University in Australia, the answer was simple: you go as far away as possible.

They teamed up with German company EOMAP to use satellites to capture a highly accurate rendering of the entire reef - half of which had never been mapped before.

The maps produced by EOMAP will help companies and researchers in a variety of fields to make ‘big picture’ assessments of the Great Barrier Reef.

Areas of research that could benefit include water quality modeling, measuring the impact of natural and man-made events (such as sediment transportation and tropical cyclones), and helping to predict the likely impacts of climate change effects, such as sea level rise and increased tropical cyclone frequency.

It will also help scientists gather information about the species that inhabit the reef. For example, the improvements that better maps bring to ocean current modelling have already been shown to help researchers track populations of starfish and their larvae.

The Great Barrier Reef stretches for more than 1,600 miles along the coast of Queensland, in north-east Australia.
The EOMAP team used satellites to map the shallowest areas of the Great Barrier Reef. (EOMAP)
While areas have been mapped before, it has been impossible to cover the shallowest sections of the reef - which make up nearly half of its total area - due to the potential damage that might be caused by ocean survey vessels.

The shallow reef areas are among the most ecologically diverse of the whole reef, and are often too remote for naval mapping.

EOMAP got around these problems by using satellite imaging technology, capable of capturing the topography of the reef at a greater level of accuracy than traditional techniques.

The entire area of the reef has been mapped at a horizontal accuracy of 30m.

Using satellites brings its own difficulties, however.
A visualisation showing the level of detail possible using satellite bathymetry. (EOMAP)
The technique used is known as satellite bathymetry, and it consists of analysing the wavelengths of reflected light to determine the depth of the water below.

EOMAP processed the satellite data to remove reflections, cloud cover and atmospheric interference, as well as correcting the results to account for high and low tide, and turbidity - a measure of the cloudiness of the seawater.

The maps are accurate to the nearest 10cm of depth, as well as to the nearest 30m horizontally. The team are already demonstrating even finer levels of accuracy. At its best, the EOMAP data is accurate to within two metres - a level that they want to roll out across the reef.
An example of the high-resolution mapping available. (EOMAP)
“Based on our trials, this promises to be an even more astounding product,” says Dr Magnus Wettle, Senior Scientist at EOMAP.

“To be honest, I’d like to see the Australian Government partner with us on this, our next endeavor, so that it would belong to Australia as a national resource,” he said.

“Having said that, our priority is to make it happen, so we have to be prepared to be pragmatic.”

Currently, the maps are available to purchase in 20sq km sections, with a minimum order value of $500. A less accurate version - accurate to within 500m - is available online for free.