A community beach monitoring app is one of the tools scientists are using to help understand erosion along a stretch of Otago coastlines.
Dunedin beaches are one of the many attractions of the south, but the coastlines are facing threats due to climate change.
Otago University's Professor Wayne Stephenson says sea level rise are storms are becoming more frequent and intense, increasing the risk of coastal erosion.
"That's the thing about New Zealand's coastlines, we are exposed to very high-energy events."
The stretch of beach between St Clair and St Kilda is used to constant change.
Since 1860, there have been four different sea walls built at St Clair Beach, each has been damaged by the elements.
In 2013, king tides saw massive sinkholes emerge along the esplanade.
Several groynes have been constructed, and sand has been imported, but erosion continues.
"It's well over 100 years since we witnessed the natural beach on this coastline so it's a highly modified piece of shoreline," says Stephenson.
Now the focus is on future protection with coastal monitoring work underway as part of Dunedin City Council's St Clair- St Kilda Coastal Plan adopted earlier this year.
It introduced a new technology, Coastsnap, to better understand coastal activity.
"Coastsnap is a tool that's used basically as a citizen science piece to understand how the beach changes over time and how it responds to storms, high tides and so on," says DCC's Engineering Services Team Leader Jared Oliver.
It's as easy as beachgoers downloading an app, and taking a snap, which is then uploaded for scientists to analyse.
"Anybody can look at those photos and use them for analysis," says Stephenson.
"It's publicly accessible data, it's not hidden behind a paywall, it's not hidden in someone's database in the university."
The two Coastsnap tools are placed at either end of the coastline- at St Clair Beach, and Lawyers Head.
The total cost to design and install was just over $3000.
Stephenson says it's a big advantage over traditional techniques.
"They're low-cost, they're unobtrusive, they're always there so they provide a lot more data than we might otherwise be able to get just through our sort of scientific research."
The fixed phone cradle ensures all pictures are taken from the same point which helps to give an accurate picture of just how much the environment can change over time.
"We can actually what we call geo-reference the photo and we can extract from the photograph where mean high tide is for example, where the base of a dune is where the top of the beach is," says Stephenson.
He says getting images from a consistent data point will allow better decision-making in the future and help scientists keep an eye on the ever-changing coastline.
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