Recreational Renaturalisation

The Concept

To take the opportunity that the regeneration of the Ōtākaro Avon River red zone corridor allows, to reimagine the area in and around Kerrs Reach to provide renaturalisation of the river and its flood plain and development of optimum recreational opportunities.

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This would involve:

  • Naturalisation of the river bank and edge, using treatments that embrace new technologies for attractive river bank designs that utilise native plants, deter exotic geese and ducks, and dampen reflected wash from water craft thus removing the need for wide shallow-angled banks;
  • Re-positioning of the river stopbanks to accommodate a flatwater sports course 2,150m long x 160m wide x 4m deep, between the west corner of Avondale Bridge straight up to and into Avon Park;
  • Adaptive management based on modelling the river’s resilience to natural hazards and climate change considering inundation from high rainfall, tidal surge and sea level rise and maximising opportunities for quality recreation and progressive ecological restoration of the river corridor;
  • Small breaches in the stopbanks to allow small bridged side channels connecting to a lattice work of tidal waterways and wetland bush on both sides of the river these being more extensive on the western side particularly within the Horseshoe Lake red zone and contained within the regeneration planning area with outer stopbanks at the outer fringes protecting residential areas and/or other assets;
  • Consideration of free flow through the Horseshoe Lake confluence (this could possibly still include provision to pump flood waters out);
  • Inclusion of a wider section at the northern end suitable for waka ama;
  • A network of interconnected pathways for cycling and walking and of waterways for exploring via small boats such as kayaks and canoes;
  • On the west of the river, location of the WhoW Wai Huka o Waitaha whitewater and surf park which will utilise small volumes of ground water (from an aquifer separate from those supplying our drinking water) in a way that allows the integration of the artesian flow into the natural river system akin to a spring-fed source with opportunities for swimming (as well as having space for swimming at the park itself);
  • Retention of New Brighton Road at its current location probably raised and with at least one further minor bridge allowing interconnection of minor waterways between Dallington and Horseshoe Lake navigable by small boat.

The Challenges

  • Sedimentation – periodic dredging would likely be required to maintain the 4m depth and to prevent weed growth, which would be an ongoing cost;
  • Flow – is not likely to be an issue for flatwater sports;
  • Re-shaping Kerrs Reach – this may be considered by some to be significant however it is already a highly engineered part of the river and a re-working of the stopbanks and river containment is likely to be needed for flood management anyway to provide a renaturalised floodplain;
  • Water quality – currently river water quality is poor – it still receives sewage overflows in high rainfall events - secondary contact sports do currently operate in this environment albeit with considerable care, but it is not suitable for primary contact (ie swimmable), however the public is now demanding significant improvements in river water quality that are being heeded by authorities.  Enhancing the capacity for flatwater sports with an in-river course would provide further impetus for improving water quality.
  • Costs – this concept could be adapted in different ways and the costs are yet to be established. It is intended to promote discussion of integration concepts for river uses and naturalisation.

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The Advantages

  • We get to have our cake and eat it too: ie recreational facility that meets the needs of all flat water codes and a renaturalised river floodplain that produces the most benefit to the most people whilst also respecting its nature;
  • Resilience to sea level rise and flooding;
  • A stunning natural playground with high synergies with other proposals for the red zone and tremendous tourism potential;
  • A reason for Christchurch to seriously tackle water quality in our urban rivers;
  • Greatly increased opportunities for improved mahinga kai values including enhanced inanga habitat in the Horseshoe Lake area;
  • A flat water sports course that meets all the requirements for training and competition for all codes;
  • Retention in situ of current Kerrs Reach facilities;
  • Retention of significant infrastructure that would be expensive to move or re-direct including New Brighton Road.