Coastal Management

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:

Item For 80mm Per lineal metre
Rock Seawall $760,00

$9,500
 Geotextile Bags $500,000  $6,200
 Backstop Wall $490,000  $6,125
 Naturalistic Concrete $1,120,000  $14,000
 Temporary Groynes (5-year consent)  $320,000  $5,400
 Sand push-ups  Between #1,000 and $4,000 per 1,000m3  

 

Coastal Management Timeline

This is a timeline of reports, groups and action plans over the past 20 years looking at how to better manage coastline around the Coromandel.

January 2020: Coromandel Coast Summer Survey is launched to find out how our residents and visitors value and use the iconic Coromandel coast.

August 2019: Our Council hosts community information sessions, reaching out to glean stories and knowledge of our coastal environment to help inform our shoreline management plan project. 

2019: Our Council embarks on a milestone project to develop Shoreline Management Plans (SMPs). This is a three-year project to  define the flooding and erosion risks to people and the social, cultural, economic and natural environment across all parts of our coastline over the next century and beyond.

June 2018: Coastal Management Strategy adopted by our Council. 

2018: In early 2018 our Council adopted the Government's revised climate change guidance based on forecasting assumptions the Ministry for the Environment published in December 2017 This means a potential sea level rise of up to 1.88m by 2150 will be taken into account for all major infrastructure projects adopted as part of our Council's 2018-2028 Long Term Plan.

2015 - 17. Coastal Erosion Plans and Programmes developed or revised for Mercury Bay, Tairua, Pauanui and Whangamata

May 2013 -2016. Coastal protection walls are built or extended in Whitianga and Cooks Beach.

April 2013. Mercury Bay Community Board endorses the Draft Whitianga Coastal Action Plan.

Dec 2012. Draft Whitianga Coastal Action Plan goes out for public feedback.

Mid- 2012 Whitianga Coastal Action Steering Committee formed. Made up of Council staff, Regional Council staff, local iwi, community board members, affected property owners and ratepayers the Committee is working towards an action plan for short, medium and long-term work to find solutions for coastal erosion along Buffalo and Brophy's Beaches.

2011 (August): Whitianga Coastal Futures Project: Joint project between Waikato Regional Council (Resources Use, Policy and Strategy and Information groups) and Thames-Coromandel District Council.

2011: WRC report on community perceptions of coastal processes and management options for coastal erosion. Coromandel Peninsula case studies include Whangapoua and Tairua communities.

2010: WRC report on Buffalo Beach Focus Groups.

2009: WRC Regional Policy Statement review including managing coastal hazard risk. The review essentially builds on the research and policy development initiatives outlined above.

2009: Our Council reviews and refines the high risk primary development setback using improved data and methodologies available.

2007: Our Council adopted a policy framework for dealing with coastal protection structures on Council administered foreshore land embracing coastal living with natural erosion processes, rather than seeking to control them, but managing human activities accordingly.

2005: WRC commissioned report: Managed Retreat from Coastal Hazards: Options for Implementation.

2004: Beca coastal management reports for Cooks & Buffalo beaches commissioned by EW and our Council The reports analysed the current state of coastal science for each of the beach systems, examined a range of management options and recommended a preferred option for each of the beaches' hotspots.

2000-2002: Environment Waikato (EW) technical report: Coromandel Beaches: Coastal Hazards & Development Setback Recommendations and the 2002 summary: Coromandel Beaches report - which reviewed data to 1999 and included recommendations for managing coastal development including revised coastal set-backs and dune management.

1999: Buffalo Beach Collaborative Committee established

1998: Tonkin and Taylor 1988 Coastal Management strategy report published.

1991 to present: Resource Management Act controls in regional & district planning instruments including the Regional Policy Statement, Regional Coastal Plan and the District Plan.

Early 1980s (1979-81): Coastal setbacks developed for the Coromandel Peninsula by the Hauraki Catchment Board (HCB - a predecessor organisation to Waikato Regional Council) and used by our Council when assessing coastal development and beach-front building proposals.

Coastal Management Methods

There are three broad approaches to managing our coastline:

  1. living with natural processes,
  2. natural defences or;
  3. building coastal structures.

These options can be broken down into more specfic details.

Living with Natural Processes

National policy and international best practice is now directing councils to consider living with natural coastal processes whenever possible. This is a way of protecting natural values and improving long-term resilience of coastal communities in the face of future sea level rise and climate change (Whitianga Coastal Futures Report, May 2012). Managing use and development of the land to lessen risks to human assets, rather than trying to manage the natural processes to prevent erosion of the land.

Enhancing Natural Defences

Dune Restoration:

Proactive restoration of a frontal dune by replanting with native sand binding species (spinifex, knobby club rush, muehlenbeckia, native spinach and sand coprosma) then fencing to restrict access while plants re-establish. In some cases it’s necessary to reshape the dune before planting can occur.

Beach Scraping

Once a beach has recovered following an erosion event, a shallow layer of sand is moved from the beach onto the upper beach face and dune to reform the dune shape. Sand binding plants are then used to prevent wind erosion. This method doesn’t prevent or reverse erosion but can speed up natural dune and beach recovery. This method was very successful at Whangapoua Beach in 2008 following a severe storm.

Coastal Structures

Seawalls

These types of walls are constructed parallel to the coastline. The primary purpose of this type of seawall is to protect the land behind from wave action. These seawalls can either be constructed with rock or an engineered-structure (geotextile bags)

Groynes

These are narrow structures (usually made from rock or an engineered structure) and built at right angles to the coastline.

Offshore Breakwaters

These structures are usually built parallel and offshore to the coast. Wave action is either dissipated, reflected, refracted or diffracted resulting in reduced wave energy. The breakwater is built either submerged or emerging from a low tide. Both groynes and breakwaters hold sand in a certain area of the beach, but means other sections of beach get deprived of sand, causing erosion there.

Geotextile Walls

Often called “sand sausages,” these are containment bags made up of robust geotextile designed to be filled with local sand or sandy gravel mix. These form a durable container for the construction of seawalls or groynes. The coarse surface in combination with the beach sand provides long term resistance to UV damage as well as puncturing. 

Waikato Regional Council's role: Waikato Regional Council handles managing the region’s rivers and their catchments, including the effects of flooding and erosion. As part of the Peninsula Project, we’re working with local communities to better protect them from frequent flooding and erosion through river management, soil conservation and flood protection works, and animal pest control on private land. We’re also responsible for undertaking works and services in the coastal marine area (CMA). 

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.

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