Sea Link Makes Sense But Land-Based Marine Services May Flood

Thames-Coromandel District Council has received a report on the proposed Kopu Landing Site Upgrade. The preferred option is to build a new slipway and at least a single berth pontoon or wharf, to support an expanded marine service industry for the aquaculture industry in the Firth of Thames.

The report talks up the perceived positives in growth in aquaculture.  But it pays only lip service to the downside risks to the aquaculture industry from warming seas and ocean acidification and to the onshore marine service industry from sea level rise and flooding at Kopu.

Positives

An expanded wharf at Kopu which was future-proofed to cope with rising sea levels would be a positive initiative.  Rising seas will provide more freeboard for vessels, provided upstream land practices are controlled and sedimentation does not increase.  

We have already seen major road closures due to slips and coastal flooding and these impacts on roading infrastructure will become more severe with climate change.  It is conceivable that Thames Coromandel will become isolated for days or even weeks.  Having alternative transport links by sea will become ever more vital in coming decades.

Glaring Gap

The glaring gap in the report is the failure to consider the risk of sea level rise to the proposed land-based expansion of marine service businesses at Kopu. 

The sea flooding maps from Waikato Regional Council have been available for over 2 years, but once again they have been ignored.  They show that under a modest sea level rise scenario much of Kopu industrial area would be inundated from the sea.  This map shows an indicative scenario for 0.5m of sea level rise and a mid-range storm surge. 

Even at modest present-day scenarios with a low/moderate storm surge saltwater intrusion (green areas) into groundwater in the Kopu industrial area is likely according to this WRC map.

A few kilometres to the north at the Thames airfield another report on the proposed new swimming pool confirms that the current seawall would be overtopped, and major expenditure would be required to raise the seawall.

Sea Level Rise Will Happen At Kopu Too

The report notes that the Sugarloaf Wharf near Coromandel is highly susceptible to climate change and severe storm impacts through storm surges and cites this as a reason for an alternative landing site at Kopu but fails to acknowledge that the Kopu site is also susceptible to sea inundation.  The entire Kopu landing site was inundated in the January 5 2018 storm surge event.  Sea level rise will not be restricted to the Sugarloaf site.

The report also fails to reference a recent in-depth study on the impacts of climate change and sea level rise on the lower Waihou River – Climate Changes, Impacts and Implications for New Zealand to 2100 Synthesis Report: RA2 Coastal Case Study – The Firth of Thames and Lower Waihou River

Here are some of the Waihou Report’s most relevant conclusions for the Kopu Landing Site –

• Sea level rise (SLR) will result in increased flooding of shore communities
• SLR is the main contributor to changes in saline intrusion and flooding
• The largest impact of SLR and flood interaction will occur in the lower Waihou River
• Salt water intrusion is an important phenomenon in coastal zones, and can create a serious problem to people and communities due to the need for fresh water for potable water services, agriculture and industry

The Waihou report specifically identifies the Kopu industrial site as being “vulnerable coastal infrastructure”

Lip Service

Ignoring or paying lip service to climate change and sea level rise has been a consistent and disturbing trend in reports commissioned for TCDC. Recent examples include reports for the Longview and Waterways subdivisions in Whitianga, the Whitianga town upgrade, the Richmond villas apartment building in Thames and the proposed new swimming pool at Thames.

It’s as if the Council has this “magical thinking” that the projected severe climate change impacts will not happen if they just refuse to acknowledge them and pretend them away.  

Its time for TCDC to get real and do what many other councils have done –  have a comprehensive across-department strategy to ensure that climate change is always considered and taken seriously at all decision-making levels.