Tracking the transport of ocean trash

A web-based interactive tool tracks how floating plastic waste moves around New Zealand's coastline. Initially designed as an educational tool for schools, the Ocean Plastic Simulator also has potential for environmental and biosecurity monitoring, and aquaculture.

"With the right source data, it can easily be modified to show where plastic pollution has come from or to predict movement of living things," says Ross Vennell, the Participatory tools Project Leader and a marine scientist at Cawthron. "The aquaculture industry could use it to track – or predict –larvae and spat, invasive species, or lost equipment."

You can use the online tool to 'drop' virtual plastic into the ocean in 4 different locations:

• Cook Strait
• Tauranga Moana
• Golden and Tasman Bays
• Hauraki Gulf/Firth of Thames

The tool includes information and resources developed by Heni Unwin, a researcher at Cawthron, including a section exploring the importance of the ocean for Māori, which includes stories from iwi. Heni tested and refined the tool and its content with help from school students and teachers.

Feedback has been positive.

"It really helps people visualise what is going on – if you drop a batch on the Tauranga map you can see how the estuary 'breathes' it in and out," says Heni.

"Most people think if you drop plastic off the Taranaki coast it'll end up somewhere on the South Island's West Coast – dependent on winds and time of year it’s most likely to end up in Kapiti or can even wash up on Wairarapa beach."

How the tool works

The Ocean Plastic Simulator combines regional models of tides, winds and currents with a 'particle tracking engine' and maps to simulate the path taken by plastic water bottles floating in the top 3 metres of the sea, and how long they take to get to their destination. It takes less than 10 secs to simulate movement of 100 pieces of plastic over 30 days, or until they are beached.

"We can simulate millions of pieces over a much longer time period in the offline computer model, which is what's needed for practical applications such as environmental monitoring, but the processing power needed to do this isn't practical for the educational online tool," says Ross.

Next steps

In 2020 the team will:

• Expand the tool to include all New Zealand's coastline
• Speed up simulation run times
• Investigate other applications, eg tracking invasive aquatic spread, aquaculture, and eDNA sources  

Related pages 

• Science Learning Hub (teaching resource)
• Webinar recording (video)
• Participatory tools (project page)