We're lucky to have some of the most beautiful and pristine beaches in New Zealand, if not the world, on the Coromandel, that's why we've adopted an ambitious programme to work with all stakeholders to manage the effects of climate change.
Coastal Management Strategy
Our beaches are one of the major reasons for people coming to visit and live here. Keeping them in such magnificent condition comes at a cost, given the effects of climate change, storm events and other natural processes.
In 2018, our Council adopted the Coastal Management Strategy. This sets out a range of initiatives we will be taking over the coming years to better manage our coastal assets and understand the risk of coastal inundation and coastal erosion. The 2018-2028 Long Term Plan includes $2.6 million over three years to help us put in place this strategy.
This approach to coastal management activity ensures a district-wide approach. Allowing us to better-manage our coastline from a holistic and long-term perspective. Public and private organisations work together. Waikato Regional Council, New Zealand Transport Agency (NZTA), the Department of Conservation, iwi and community groups with an interest in coastal protection.
‘Coastal management’ encompasses a wide range of projects. It identifies hazards and risks and develop Shoreline Management Plans to combat these.
The CMS was adopted by Council in June 2018.
Photo above: Whangamata Beach Access 8.
We are experiencing continued coastal erosion around our open East Coast beaches. Whangamatā, Pāuanui, Tairua, Whangapoua, Mercury Bay, and Cooks Beach are among the most notable spots.
"This is continuing as a result of storms we’ve had over the last," says our Coastal Scientist Jamie Boyle. "As well as this, we’ve identified 14 sites around the district that need monitoring and consideration of mitigation alternatives to the ‘living with nature’ approach,” he says.
Our Shoreline Management Pathways Project has identified adaptation pathways for each section of our coast, that take into account how these issues and sites are best addressed.
Jamie explains more on why this happens to our dunes which you can read below.
“Coastal erosion is a district-wide issue and the costs are significant to do any type of hard and soft work structures,” says our Mayor Len Salt. “Protecting and enhancing the dunes we have left is critical to the future of beaches and existing beachfront properties.”
The options we have to react to coastal erosion are many and costly.
"Our Council can’t go in and do works as and when it sees fit," says Jamie. "As well as construction costs, there’s also consenting and consulting costs that have to be managed, and unless we can prove that critical infrastructure is at risk (parks and sand dunes don’t count as critical infrastructure), then the process can take a very long time."
Here's some indicative construction estimates for an 80m section of foreshore:
||Per lineal metre
| Geotextile Bags
| Backstop Wall
| Naturalistic Concrete
| Temporary Groynes (5-year consent)
| Sand push-ups
|| Between #1,000 and $4,000 per 1,000m3
Dune erosion chat with our Coastal Scientist
Due to the recent storm events our dunes have eroded in Whangamata (pictured right), Pauanui and Whitianga. Our Community Facilities team are monitoring the areas.
"The current dune erosion is completely natural and the active dune that has lost sand is doing exactly what it should be doing. Providing a buffer for wave energy," says Jamie Boyle our Coastal Scientist.
- During long periods of settled weather, sand builds up on the visible part of the beach, including the dune. Short-term erosion can happen during storms, as waves erode the beach and the dunes closest to the sea. This often leaves a near vertical cut in the face of the dune (an ‘erosion scarp’) as shown by the diagram below. The eroded sand is carried offshore into the surf zone, where it forms shallow bars that help absorb storm wave energy.
- Significant dune erosion can occur in a few hours, but full sand dune and beach recovery can take years.
- After the storm, the beach area repairs itself first before the dunes can recover. Gentler wave action moves sand back to the shore, rebuilding the beach. Dry sand is then blown further inland and trapped by sand binding vegetation to repair the eroded dune.
- Natural dune repair depends on a good cover of native sand binding grasses. Spinifex and pingao are used to trap moving sand.
- Erosion through climate cycles sees shorelines on Waikato beaches move over periods of decades. The largest changes usually seen near estuary and river entrances. Though periods of erosion can continue for years, in most cases it is not permanent. When viewed over a long period, such as a hundred years, the shoreline is shifting backwards and forwards.