Erosion mapping hoped to help protect the Southland coast
Urgent action is needed as the ocean slowly consumes Southlands beaches, roads and even a landfill, a researcher says. Cassie Newman has studied the erosion patterns of four coastal areas in Southland for her masters thesis at the Auckland University of Technology. She used historic satellite images and 3D unmanned aerial vehicle techniques to map the changing coastline, where parts of the shore with human-made objects such as buildings and roads are at risk. Newman, who won the Coastal Restoration Trust 2021 Student Science Award, has now given a presentation on her findings at the trusts conference. READ MORE: * Southland District Council's aerial erosion monitoring does not include area in front of old dump site * Three of the best Southland surf spots * Three nights at Colac Bay extends to three weeks in lockdown You can see the definite patterns of erosion over time and, by understanding these changes, we can help manage and prepare coastlines for the future, which of course includes climate change, Newman said. Her research focused on historic and seasonal patterns across Monkey Island, Colac Bay, Fortrose, and Porpoise Bay, and was some of the only data available for local authorities to work from. Newman said she spent about a year in Southland completing her research, and it appeared nobody was taking urgent action to remedy the issues. The Colac Foreshore Rd, closed due to erosion , was one example of affected human infrastructure, Newman said. Without taking steps to mitigate the continued erosion, the landfill behind the road could cause issues for local marine life and the environment. The (Colac Bay) shoreline has eroded about an estimated 1 metre on average a year, based on my research, which is quite a lot, Newman said. It seemed there was no sense of urgency to do something about the landfill, as the old coastal road is almost gone because of erosion. There was a Hectors dolphin population in the area that could be impacted if the coast eroded enough for the landfill to leach into the moana and create a toxic environment, she said. Erosion at Fortrose was less severe than Colac Bay due to its location and the clean materials that have been used to mitigate erosion, Newman said. Fortrose has old building materials like bricks and concrete used to prevent erosion which has worked, so thats stopped the coastline from eroding. In Porpoise Bay there were signs of erosion were clear, however, Newmans data showed there would be a natural buildup of sediment and sand along the coast, counteracting the impacts of erosion. There is really distinct patterns of accretion and erosion occurring about every 10 years. It was cool to see there is a natural pattern. Newman said understanding the issue was the first step. She hoped the research would help to inform local authorities making decisions about coastal erosion protection and developments in the future.