Submission to Waimakariri Water Zone Implementation Plan

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Dwayne Chambers
5 years ago
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1 Submission to Waimakariri Water Zone Implementation Plan Greg Bennett Holton Road RD1 Amberley I would like to acknowledge the Zone Committee for the work they have done to get the Draft ZIP released for comment. I spent three years as a member of the committee which developed the North Pegasus Bay Coastal Management Strategy and three years as a member of the committee that is currently developing the Waipara River Management Strategy. I understand the commitment it takes to assimilate screeds of information, attend workshops and meetings and then attain consensus to find a way forward. Well done. I am also a Trustee of the Dune Restoration Trust of New Zealand. We recognise that coastal wetlands form an integral part of the dune ecosystem. We have been working with Te Kōhaka o Tūhaitara Trust to source MFE funding for back dune planting trials between Woodend and Waikuku. As you know Te Kōhaka o Tūhaitara Trust has commenced an ambitious restoration of their wetlands which includes Tutaepatu Lagoon. The ecological links between the coastal wetlands of Pegasus Bay creates opportunity to develop cross boundary relationships between the Hurunui- Waiau and Waimakariri Zones. I advocate for coastal wetland management for the entire Pegasus Bay. Coastal dunes are the most degraded ecosystem type in New Zealand. European settlers introduced cattle, sheep, goats and rabbits. Beaches were the first areas to be grazed and the dune vegetation was quickly consumed. This caused mass movement of sand around the country to which the response was to plant introduced marram grass (Ammophila arenaria) which successfully halted the movement of sand. Marram was effective at stabilising inland sand dunes however it does not cope well with recovering from sea erosion of our foredunes. Our native sand binders Kowhangatara/silvery sand grass (Spinifex seriseus) and Pikao/golden sand sedge (Ficina spiralis) grow further down the foredune than marram and their growth habit of developing creeping rhizomes aid in allowing the foredune to recover quickly after storm erosion. These plants have been planted on foredunes around the country with spectacular success, often saving infrastructure and property. Beaches rely on a supply of sediment from the rivers to replenish the sand lost to coastal erosion. If rivers are dammed or the catchment is planted in forestry then the sediment supply decreases and the beach will retreat to compensate for the loss of sand. It is predicted that the effects of climate change is going to have significant effects on our coasts. Pegasus Bay is mentioned in a NIWA report 1 on the predicted effects of climate change as follows: Sea-level rise is virtually certain to cause greater coastal inundation, erosion, loss of wetlands, and salt-water intrusion into freshwater sources, with impacts on infrastructure, coastal resources and existing coastal management programs. Future effects on coastal erosion include climate-induced changes in coastal sediment supply and 1

2 storminess. In Pegasus Bay, for example, shoreline erosion of up to 50 m is likely between 1980 and 2030 near the Waipara River if southerly waves are reduced by 50% and up to 80 m near the Waimakariri River if river sand is reduced by 50%. Coasts are also likely to be affected by changes in pollution and sediment loads from changes in the intensity and seasonality of river flows, and future impacts of river regulation. Considering the above, establishing a healthy dune system along Pegasus Bay now will provide a resilient buffer to mitigate the effects of coastal erosion and seawater intrusion in the future. A wise person once said: Good oceans policy starts in the mountains. I ask that the Zone Committee consider this and the content of this submission when finalising the ZIP and include recognition on the importance of managing our coastal dunes. I enclose for your information a copy of a handout prepared for workshops that the Trust facilitated in Christchurch last year titled: Empowering Coastal Communities to Adapt to Climate Change. Please note the photo of New Brighton Beach on the cover. The kowhangatara in the foreground is advancing further seaward than the dune in the background which is planted with marram. I am happy to meet with the committee to discuss these issues further. For more information visit our website: