Sand slips away, but CoastSat keeps the score

An online tool developed by scientists at Waipapa Taumata Rau, University of Auckland allows for detailed monitoring of the nation’s coastal erosion from satellite imagery.

Around a map of New Zealand, dark red lines show the beaches eroding the most and clicking into any individual line gives detailed information going back to 1999. The data is updated once a month.

“This tool is a game-changer for anyone involved in coastal science or management,” said Professor Giovanni Coco, of the School of Environment. “Online beach monitoring for the whole of New Zealand is now a reality.”

The tool, called CoastSat New Zealand, can be used to monitor shoreline changes, assess coastal erosion, and support conservation efforts. For now, the tool is for specialists since more investment and tweaking would be needed for a version for the public.

Software engineer Nick Young of the University’s Center for eResearch and Coco built on the work of scientists at the University of New South Wales, who created an open-source software toolkit that pulls beach position data from publicly available satellite imagery.

Erosion hot spots exist in places such as Port Waikato while other places are accreting, such as Whatipu.

“As coastal areas face increasing pressures from climate change and human activity, tools like CoastSat New Zealand are essential for informed decision-making,” says Coco.

Google Earth Engine gives access to a growing archive of publicly available satellite imagery, providing the opportunity for global-scale analyses stretching back decades, Australian scientists led by Dr Kilian Vos said in a paper explaining their work.

“This project was made significantly easier by Kilian Vos providing the data and code freely online,” says Young.