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The costs of protecting our coastlines.

29 July 2014

The Coromandel is lucky to have some of the most beautiful and pristine beaches in New Zealand, however preserving them is coming at a cost.

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Our Council is now investigating how we can better plan and pay to protect our coastline that's currently at risk from erosion.

The increased frequency and severity of storms is resulting in major erosion along several areas of our coastline which is putting public reserve, infrastructure and private properties at risk.

"We're investing more money and time on coastal protection methods," says Mayor Glenn Leach.

Wide reserve areas we put aside years ago for this eventuality are almost gone. There's a need now for backstops where we can have confidence in the majority of protection being given, and then from there look at other softer methods once those backstops are in place.

"We have to draw a line," says Mayor Leach. "Over the decades we've had numerous reports and consultants giving us advice on how to manage coastal erosion. But while we understand the need for planning, we also need action. Protection works need to be done sooner rather than later because every time we wait, we're losing more of our coastline, more of our land and potentially putting infrastructure like roads in jeopardy."

"This means more direct action rather than a managed retreat," says the Mayor. "So whether that's building hard or soft wall structures along the coast, continuing with on-going dune planting and temporary sand push-up work, this is what we'll be doing to protect land and infrastructure," says Mayor Leach.

"We have to remember that beyond roads are the houses themselves. While scientists debate, trial things and postulate solutions, the real-life situation demands that we draw a line of action before we start losing any houses," says the Mayor.

Council's approach will mean where there is enough reserve width and a lower wave energy environment, the preference will be to undertake dune planting and beach push-ups. But where the reserve is mainly gone in front of roads and houses and the wave energy is aggressive, we are committed to building walled protection as a backstop. This is about matching the method to the realities of the sea.

However, to make that happen, we'll need to pay for our coastal and hazard management activity in a more dedicated way. This action is in addition to our current approach in our Proposed District Plan to managing the coastal protection zone.

One of the ways we're looking to pay to manage coastal erosion is through our upcoming 2015 -2025 Long Term Plan. This could see coastal and hazard activity becoming district-funded, which would be targeted out of everyone's rates.

"Our first funding priority has to be to essential community infrastructure, but we won't abandon private homeowners issues," says Mayor Leach. "While we can't commit to funding for private landowners, we already have successful partnerships in place with private owners where we helped them to design and fund their own protection. My council is seeing this as a whole of District issue. You don't have to go too far back to see similar issues of protection needed on the Thames coast too. Just because we have erosion issues in Mercury Bay, Pauanui, Tairua and Whangamata is no guarantee that we won't see more on the western seaboard in future also."


At-risk areas on the Coromandel and what's being done right now.

  • Whangapoua Beach - There's several properties that sit forward of the coastal setback line that have suffered severe erosion during the June and July weather events. A ratepayer meeting is being held on Saturday 2 August to review the emergency works carried out during the storms. Our Council issues consent for sand push up work at Whangapoua Beach. The consent is held by independent coastal scientist Jim Dahm who represents Whangapoua Beach residents. At the ratepayer meeting Mr Dahm is going to present options and discuss works carried out at Buffalo Beach and Cooks Beach.  In the past few years we've been working with residents on dune restoration planting which has helped protect some areas of this beach.
  • Matarangi. We are very aware of the erosion at the golfcourse end of the Matarangi Peninsula and our Parks and Reserve team have been working with Golf Course management in the past three years to maintain the walking track.  This isn't a Council track, but an informal track which is on private land. The June 10 storm took another large section of the track away and again our Parks and Reserves team re-routed and reconstructed the track to make sure it could be used. We will continue with our commitment to working with the landowners (The Golf Club) to keep the track open for people to enjoy. For other areas in Matarangi on public reserve affected by erosion we'll continue to get advice from independent coastal scientist Jim Dahm and work with the Matarangi Reserve Management Group to do coastal planting at more vulnerable areas.
  • Brophy's Beach.  A geotextile cloth wall is planned to be built behind the existing rocks to stop further erosion. We're currently working through the consents and design process with construction planned for late 2014.
  • Buffalo Beach Whitianga. A coastal management action plan has been devised for Buffalo Beach. The beach has been broken down into sections with different plans for different sections of the beach.  Area B - A rock wall extension to the existing NZTA wall was completed in 2013 A footpath was also built that connects the toilet block through to the end of the road. In June 2014 a severe weather event caused erosion between the end of the newly finished rock wall to the Buffalo Memorial. Another 120m of wall has been approved at a cost of $633,100. Construction is planned to start late 2014/early 2015 and be completed in 2-3 months, subject to the resource consent process Area C - A dune rehabilitation project in this "central' section of the beach is underway, the first on Buffalo Beach for many years. We've held two volunteer community planting days in  October 2012 and August 2013. The next planting day is planned for Saturday 16 August at 9am meeting at the Buffalo Beach Main Reserve.
  • Cooks Beach - The Cooks Beach Wall Trust, which is made up of all affected property owners, including our Council paid for a 474m backstop rock wall which was completed late 2013. In June 2014 a severe storm caused further erosion so funding of $358,000 was approved by Council to carry out design and resource consenting for an extension to this wall.
  • Tairua-Pauanui  and Whangamata - In early 2014 three Working Groups were formed to contribute in drafting an Eastern Seaboard Coastal Management Plan covering areas from Ocean Beach Tairua through to Otahu Estuary Whangamata. The three groups represent Pauanui, Tairua and Whangamata. Working with our Council and Regional Council the Working Group will address issues with erosion, dune management, coastal planting, structures and storm water risk.

 

 


 

 

Volunteer planting days

Come along to our dune planting day at Whitianga on Saturday 16 August at 9.30am as we're going to need help planting thousands of native sand-binding plants and grass species along 100m of dune systems at Buffalo Beach.

These planting days help restore and protect the sand dunes to prevent further coastal erosion.

This initiative is a joint project between TCDC and the Waikato Regional Council to manage and protect Coromandel's coastline. We're meeting at the Buffalo Beach Reserve Car Park and all you need to bring is your gloves and a spade. The Whitianga Lions Club is kindly supplying water and a sausage sizzle for volunteers.

In the past two years we have planted approximately 200m of dune with native plants, which has been extremely successful.

The planting day will occur rain or shine and if you have any queries contact scott.farrell@tcdc.govt.nz


What's the cause of the current erosion event.

 

The majority of eastern Coromandel Beaches have been at relatively low levels for some time, according to Rick Liefting, Senior Regional Hazards Advisor for the Waikato Regional Council  These low beach levels have occurred primarily due to the La Nina climate phase (+ve SOI in graph below represents La Nina conditions, -ve SOI represent El Nino conditions).  La Nina conditions usually result in more easterly winds and wave conditions winds that tend to erode (or at least do not promote beach building) east coast beaches. 

El Nino conditions usually result in more westerly wind conditions that generally promote beach building along the east coast Coromandel.


 

Natural beach/shoreline dynamics along East Coromandel Beaches.

The soft shore beaches along the eastern Coromandel undergo natural fluctuations around a ‘equilibrium’ shoreline. i.e. there are currently no long-term trends of erosion or accretion.

Based on regular (~monthly) beach profile surveys along eastern Coromandel (undertaken by WRC) it's expected that:

  • some 15% of the beach volume to be lost during a typical winter season (July to September)
  • add another 15% loss if the winter season coincides with a La Nina climate phase
  • add up to another 20% of loss due to significant wave events.

Therefore, recent erosion is due to a ‘perfect storm’ of conditions where up to 50% of total beach volumes may have been lost from the beach.

However, the sand ‘lost’ from the beach still remains in the beach ‘system’.  As sand is transported via wave action, the beach system extends out to a water depth of around 10 m – 20 m.  Therefore, the sand stored offshore will return back onto the beach during appropriate ‘beach building’ conditions.

 

 

 


 

 

 

 

 

Coastal erosion problems - We're not alone.

 

Coastal erosion and its effects on public and private property is an issue that councils around the country are grappling with. Here's a short list of some news articles on coastal erosion issues being dealt with across the county.

Auckland http://www.stuff.co.nz/auckland/local-news/eastern-courier/10038538/Erosion-at-beach-a-concern

http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11195493

Haumoana, Hawkes Bay. http://www.haumoana.com/pages/erosion03.html

Gisborne. http://www.scoop.co.nz/stories/AK1406/S00111/managing-coastal-erosion-at-wainui-beach.htm

Taranaki. http://www.stuff.co.nz/taranaki-daily-news/news/10308392/Coastal-erosion-comes-under-council-scrutiny

Kapiti Coast, Wellington. http://www.google.co.nz/url?url=http://www.newstalkzb.co.nz/auckland/news/regwn/1198926725-battle-brewing-over-kapiti-coastal-properties&rct=j&frm=1&q=&esrc=s&sa=U&ei=4KLVU5CiNsv98QXxvID4Cw&ved=0CBMQFjAAOBQ&sig2=YqDNJKBQ7XJGBR7HR2hhHA&usg=AFQjCNGj6LFMERe5VBgJNVgbB7euF63nJQ

West Coast. http://www.stuff.co.nz/the-press/news/7162089/West-Coast-township-threatened-by-erosion