Aaron chats to local environmental activist Angeline Greensill and Coastcare Waikato Coordinator Stacey Hill to hear local perspectives on the cyclical nature of erosion around coastal environments. He also interviews Rick Liefting, the Regional Resilience Team Leader at Waikato Regional Council (WRC), discussing the impact of high sea levels during recent storms and the resilience of coastal communities in the face of erosion, sea level rise, and climate change.
(listen to the full interview below:) While some locals have expressed concern on social media at the amount of land that appears to be lost to erosion, local environmentalist Angeline Greensill said that there’s ‘nothing to panic about’.
Having watched the ocean from her home down Riria Kereopa Memorial Drive for decades, Angeline has been on the frontline of change and says that looking out the window of her home is a good indicator of what’s happening in the ever-changing environment.
Back in 2003, the Wainui Reserve carpark at the end of Riria Kereopa Memorial Drive was eroding to the point where the sand was close to eating away at the road. Angeline recalls her father Tex Rickard getting some mānuka stakes (with brush woven through it) to put in the ground and within a couple of weeks, with the right winds, he was able to trap the sand as it was travelling up the beach to begin to build ‘artificial’ dunes.
“My dad always taught me you can never fight nature. You have to work with it.” Having already seen the sand moving around back in the 1940s and staking the area to retain the dunes, Tex was simply repeating what had worked in the past using the natural wind cycles and soft capture options to trap more sand. Over the years Angeline says that the sand has come and gone and it’s simply the changing nature of the environment.
Rick’s team at WRC focuses on various aspects of resilience, including responding to floods, oil spills, and natural hazards, providing guidance on risks to colleagues and landowners. They are part of a regional effort and have access to extensive information within the council.
When it comes to coastal management, Rick emphasises the need to make decisions based on solid technical information. Coastal erosion at Papahua is a complex issue with various factors at play. The natural fluctuations of shorelines and the ever-changing environment around Whāingaroa Harbour contribute to the challenges.
Rick says there’s no easy fix for managing erosion. Different options, such as soft approaches like planting and dune restoration or hard engineering like sea walls, have their advantages and disadvantages. It’s important to consider the community’s values and have discussions to weigh the pros and cons of each option. Coastal erosion management is a dynamic and demanding task.
Having worked on coastal dune planting through her work at Coastcare, Stacey says that walls and groynes aren’t always the best solution for shifting sands.
“What that does is actually bounces the wave energy around. So if you wanted to put a hard structure in and protect that coast, you’d have to put it all the way along the coast, because otherwise, you’ll get end effects or chewing at each side. It would have to be very well engineered, and we’re talking millions and millions of dollars for that,” said Stacey.
According to Rick, there’s also a noticeable rise in turbulence at the base of sea walls, which leads to issues with scouring. He also pointed out that sand gets trapped behind sea walls instead of following its natural path along the coast. This could potentially result in a shortage of sand in other areas where the sand would naturally flow.
“We go down the soft engineering path and we use the native plants to trap sand and build those healthy dune systems. Then we have that buffering of erosion and we have that natural give and take to the sea,” Stacey adds.
For the Whāingaroa harbour specifically, Rick says that alongside the soft sand, there are volcanic materials underneath that provide stability. If you check out the WRC coastal hazards tab on the Regional Hazards Portal Waikato Regional Hazards Portal (arcgis.com) , you’ll notice that the shoreline near the toilet blocks at the harbour mouth has remained quite stable. This is because there is a hard structure beneath the sand. However, as you move further into the harbour, the geology primarily consists of sand, which is more susceptible to changes and less sturdy compared to the harder materials.
Rick says our black sands here in Raglan are primarily made up of titanomagnetite, a volcanic sediment originating from Mt Taranaki. While we know that the sand travels from south to north along the coast, we’re uncertain about the length of the cycles (which appear to last decades or more) and the size of the sand deposits. The cycles of sand movement are influenced by large rivers mouths, harbours, and headlands that can trap sand, requiring wave and current action to continue the progression north.
Historical shoreline analysis reveals that the shoreline is currently at a similar position as in the 1940s, with periods of growth, reduction, and erosion since then, indicating a natural phenomenon.
Rick mentions that we have knowledgeable people in the Raglan community (like Angeline and Stacey), with valuable expertise in understanding coastal processes and hazards that can help us to understand how to respond to issues like coastal erosion.
Having worked all along the west coast of the Waikato from Port Waikato to Mōkau, Stacey says that sometimes you just have to let nature do its thing and wait for the cycle to come back again.
“If a site is going through active erosion, then we can’t do any planting there. So you’re likely to see more eating away and we need to let it do its erosion thing – which may be years, we’re talking cycles of erosion that can even take decades.
“ Sand will always come back. Following erosion, we will see accretion (as a natural cycle), we just need to be ready to plant to catch the sand when it comes so that we can build these areas back out again, ” said Stacey. Meanwhile, Angeline says it’s encouraging to see people caring about erosion in Whāingaroa and that they are always looking for people to help with planting around the community.
If you’d like to know more these videos show how things work: How Beaches Work https://vimeo.com/711843028 and Fighting Nature https://vimeo.com/713898024 from the Coastal Restoration Trust If you’d like to get involved, check out Coastcare Waikato FB page to stay up-to-date on upcoming planting days. https://raglanradio.com/wp-content/uploads/2025/06/20201010_113136.jpg