Many nations depend on and have strong historical ties to the finite resources the oceans provide; the United Arab Emirates (UAE) is no different. In recent years, the UAE has greatly increased monitoring of its unique coral reefs, concerned not just about the harmful effects of climate change, but also to mitigate the loss of coral due to the impacts of marine construction projects.
The UAE has led and commissioned extensive coral reef research, generating data that paints a disturbing picture of the extent of coral bleaching in particular. Coral bleaching is a phenomenon where coral reefs turn white due prolonged stress such as; high water temperature, nutrient rich water (i.e. sewage), sedimentation due dredging or reclamation activities and more.
The frequency of mass bleaching events has increased over the past 30 years. It's estimated that more than 65% of coral reefs in the UAE have been wiped out due to rising water temperatures1,with the remaining coral on the edge of survival. Damage to these reefs reflects a global trend, driven by high greenhouse emissions and rising global temperatures.
Accurately mapping coral reefs and monitoring their health is therefore an important part of addressing and tackling the challenge. Similar to the UAE, much time and effort has already been invested in many parts of the world, with a view to developing comprehensive conservation and management plans for these valuable ecosystems.
To support this, GHD has recently been pioneering the use of 3D modelling technology, an approach that is already delivering data-rich and visually stunning digital replications of these threatened natural wonders.
"It's a little bit like the concept of Google Street View," explains GHD marine biologist Prasanna Wijesinghe, who is based in the UAE. "We're using increasingly powerful and flexible 3D modelling technology to develop incredible digital representations of underwater coral reefs that can be navigated and explored, like current virtual reality games."
"With the 3D modelling approach we still use divers, but effectively. It's a case of taking a number of overlapping still images of a coral, and then letting the advanced software 'knit' everything together to render a 3D model," says Prasanna. "Currently, we are focused on obtaining extremely accurate models of singular coral colonies. Once we have the basics mastered, it’s a case of increasing scale to produce holistic 3D models of entire reefs."
Traditional coral modelling techniques typically rely upon teams of divers, who swim along the reef recording observational data on a slate, or similar, usually focusing on the extent of live, dead and bleached coral cover. The obvious problem with this approach is that the data captured tends to be subjective and involves visual estimations. Surveyor-bias can lead to 'cherry-picking' of data, causing discrepancies between different surveyors for the same data sets, hence such data can be difficult to accurately comparable over time.
Once the model is rendered in 3D, it's as if the reef is "frozen in time", explains Prasanna. "The key point is we can go back later and extract whatever data we want, which is close to impossible with conventional surveying methods."
3D coral models were created using a method called photogrammetry using Structure from Motion. This is an image processing technique that matches features in successive overlapping images to construct accurate and manipulable 3D models.
While the rendering process can require a bit more time to generate the final model and associated data benefits, Prasanna is quick to point out that as technology continues to improve rapidly, processing times will diminish.
"While this approach is still in its infancy, it's not unrealistic to expect to see the underwater world of corals mapped in the not too distant future," says Prasanna. "I'm excited by the possibilities, and proud to be leading this pioneering work from GHD."
Footnotes:
About the Author
Meet Prasanna
Prasanna Wijesinghe is a Marine Biologist and Environmental Scientist based in Abu Dhabi. He specialises in underwater 3D coral modelling, and his experience includes projects ranging from bioremediation of water, gathering of marine baseline data for marine protected areas, relocation works, and ecological and offshore surveys.
For more information, you can contact Prasanna on +971 2 696 8700 or email him at Prasanna.Wijesinghe@ghd.com
