Friday, 25 September 2020

WHITIANGA WEATHER

Erosion at Buffalo Beach - Boating Club clubhouse may be forced into managed retreat

On our frequent morning walks along Whitianga’s beautiful Buffalo Beach, over several years, my husband and I normally approached the beach from the launch ramp at the clubhouse of the Mercury Bay Boating Club.  The launch ramp and the boating club surrounds were popular access points for many local and visiting beachgoers.

Unfortunately, with the easterly weather and wave patterns over the last few years, the launch ramp no longer exists. The beautiful dune plantings, access trail and a big chunk of the dunes in front of the clubhouse also no longer exist. They have all been replaced by a 1.5m metre high cliff of sand. 

Sadly - although there have been a huge amount of dune restoration carried out by endless volunteers working with Thames-Coromandel District Council and Waikato Regional Council, and “sand push up work” by diggers trying to stabilise the dunes - Jonathan Kline, commodore of the Boating Club reckons that after maybe 10 more easterly weather events, the dunes will be totally gone. While Jonathan praises the efforts to push the sand up from the waterline at low tide to brace the dunes, he says these efforts are further lowering the beach, making it even more prone to wave impact from large easterly weather systems, of which we have had quite a few over the last couple of years. 

Apparently in 1997, when the Boating Club clubhouse was built on TCDC land, the club provided a waiver that if affected by erosion, then council carries no responsibility. In other words if the erosion continues, the clubhouse will have to be moved (manged retreat). The building was designed to be relocated, but at a cost the Boating Club cannot afford.

Immediately to the north of the Boating Club clubhouse, two large pohutukawa trees are literally hanging onto life by a thread with their root systems exposed and drying out. The property on which the trees are situated has lost a large chunk of land as have the next couple of properties which are not currently being shielded by a privately funded rock wall protecting their northern neighbours. The homes behind the rock wall all appear to be safe at this point.

The rock wall was built under urgency in 2000 by a group of desperate property owners known as the Buffalo Beach Home Owners Association in response to the damage caused by three back-to-back cyclone systems which took at least 10 to 12 metres of dunes. Since 2008, the group has been working with TCDC and WRC to reconsent and improve the wall, possibly extending it a short distance to their unprotected neighbours to the south. It has been a long and complicated process. Any extension of the wall will in all probability be too late to save the pohutukawa from toppling into the ocean. 

The underlying problem in layman’s terms, is that Buffalo Beach is quite long and does not offer much in the way of natural curves to build up sand deposits caused by the continual counter-clockwise lateral flow of sand.  This current of sand then moves out into the Bay towards a burgeoning ebb tide sandbank which is growing offshore. At the same time as the sand is moving out, the shape of Mercury Bay makes Buffalo Beach prone to northerly and easterly wave actions and storm surge effects. 

This coastal process is not new and erosion at Buffalo Beach is not new. According to a report by WRC in 2006, which included a historical perspective on the management of the erosion, before the 1960s there were reports of erosion, but the dunes were ample and the beach much wider to protect Buffalo Beach Road (then a state highway) and Whitianga town. After the well-documented tsunami event in 1960, the erosion - likely caused by offshore seabed changes and a seaward widening of Buffalo Beach Road (then a state highway) - caused central government to place rock armour along the waterfront to protect parts of the road and The Esplanade area.

From the mid-1990s, the northern end of Buffalo Beach started to retreat significantly. That led to the action taken by the Buffalo Beach Home Owners Association and more recently extension of the rock wall initially placed by the government and a sand bag wall at Brophy’s Beach.

There have been numerous studies of the erosion at Buffalo Beach - initiated by TCDC, NIWA, other government agencies, academic institutions and the desperate homeowners of the Buffalo Beach Home Owners Association. TCDC has a timeline on their website of 23 such reports and action plans since 1979. Outside of the academic institutions, most have been prepared by consultants, funded by tax and ratepayer money. There is consensus about what is happening.  Unfortunately, there does not seem to be consensus on the way forward.

Groynes have been proposed various times and even trialled in the 1980s in the form of gabion baskets which were reported to successfully deposit sand along the beach. Those temporary groynes had to be taken out after some deterioration of the baskets. In 2015, TCDC engaged consultants, Tonkin and Taylor, to look at obtaining consent for the trial of wooded piling and lagging groynes. The result of the consent process, according to council, was that some negative community feedback was attracted, the groynes were not favoured by WRC and DOC simply would not approve them. Thus, there was a shift from harder options to softer options like dune planting and restoration, and the funding shifted in that direction.

TCDC is expecting that their wide-ranging Shoreline Management Plans project, which is currently underway, will contain plenty of information on erosion and inundation hazards along Buffalo Beach. The information will be used when management of the hazards will be considered in the next six to nine months.

How the stretch of beach in front of the clubhouse of the Mercury Bay Boating Club will be looking at that time, is anyone’s guess.

See below for a statement by Councillor Denis Tegg, the Thames-Coromandel constituency representative on Waikato Regional Council, on the erosion at Buffalo Beach.

Statement by Denis Tegg on Buffalo Beach Erosion

Advice taken from coastal hazard experts at Waikato Regional Council confirms that there are number of processes at play which make the erosion at Buffalo Beach in Whitianga a complex situation. Hard structures such as the Buffalo Beach Homeowners Association seawall impede public access to the beach and can potentially cause more erosion at each end. Coastal erosion is a natural process with shorelines varying between periods of sand erosion and accretion (building up). If there was a quick, easy, inexpensive fix, it would have happened by now.

A team of world-renown New Zealand climate scientists lead by Professor Tim Naish, who have just won the Prime Minister’s science prize, confirm the following -

• Global heating has already caused around 20cm of sea level rise and the rate of rise is accelerating. 

• A further 30cm of sea level rise by around 2050 is “locked in” due to greenhouse gas emissions already in the atmosphere.

• 30cm of additional sea level rise will mean present-day damaging storm surges of one-in-100-year intensity will occur annually

• If, globally, we continue the current “business as usual” emission pathway between 1m and 1.5m of sea level rise is projected by the turn-of-the-century. 

• This is expected to worsen the trend for shoreline erosion. 

• Coastal flooding is projected to be an even greater problem, threatening many coastal cities, towns and settlements.

The New Zealand Coastal Policy Statement is binding on all local councils. The policy requires councils to consider the latest science on climate change and sea level rise over at least 100 years, and to avoid activities which increase the risk of coastal hazards, ie not allow such activities. 

WRC has jurisdiction on the seaward side of mean high-water springs. Thames-Coromandel District Council has jurisdiction inland from that line. The status of the land potentially impacted by erosion, whether it is private or public, has no bearing on these joint responsibilities.

Unfortunately, much of our coastal development on the Coromandel Peninsula has occurred too close to the sea and now our communities are facing massive costs as the impacts of climate change and sea level rise start to bite.  Measures proposed for the length of one rugby field at Flaxmill Bay are estimated to cost close to $1 million for a standard rock revetment wall and groynes. Local residents prefer a “naturalistic” wall which would push the cost out closer to $2 million. 

WRC is collaborating with and providing expert assistance to TCDC’s Shoreline Management Plans project.  Community Panels will soon be formed and these will help inform the project. The panels will recommend responses at Buffalo Beach, numerous other sites in Mercury Bay and scores of sites elsewhere around the Peninsula where coastal flooding and erosion is a threat. 

The SMP project will first need to assess which areas around the Coromandel’s coast are most at risk and prioritise action. The panels will have some tough decisions to make because fully protecting all the at-risk areas is unlikely to be practicable or affordable for TCDC ratepayers.

Pictured: The erosion at Buffalo Beach in front of the clubhouse of the Mercury Bay Boating Club in Whitianga. The pohtukawa trees in the distance are at risk of toppling into the ocean.

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