Kete Tiles

Name of case study

Kete Tiles

Location

Te Whanganui a Tara, Wellington, Aotearoa New Zealand

Year

 2021 – 2022

Scale

40 tiles along a stretch of urban coast

Area / size

Each tile is approximately 0.25m2

NbS employed

Living seawalls / biodiversity tiles

Type of NbS

Engineered intervention (not using vegetation)

Initiator

Wellington City Council

Funder

Wellington City Council & Waka Kotahi

Budget

Unknown

Design group

 Isthmus; Tonkin and Taylor; Hutt Concrete Products

Kete Tiles. Photo from Wellington City Council
Climate change benefits
  • Changes in phenology 
  • Coastal erosion
  • Coastal inundation and storm surge
  • Ocean acidification
  • Sea level rise
Societal / socio-cultural benefits
  • Disaster risk reduction and resilience
Ecological benefits
  • Biodiversity health and conservation
  • Biological control (regulation of pests and disease)
  • Disturbance prevention (erosion, storm damage, flooding etc.)
  • Genetic resources (diversity)
  • Habitat provision
  • Purification (of water, soil, air)
Kete Tiles. Photo from Wellington City Council

Summary of case study

Part of the Cobham Drive project in Wellington, funded by Wellington City Council in partnership with Waka Kotahi, features Wellington’s Kete Tiles. This initiative is part of Paneke Pōneke, a citywide network of safe biking and scooting routes, and also contributes to Te Aranui o Pōneke, the Great Harbour Way.

The Kete Tiles, made from special concrete with a woven surface resembling harakeke kete (woven flax baskets), are being affixed to the new rock embankment at the southern end of Te Whanganui-a-Tara (Wellington Harbour). Their purpose is to aid marine life establishment by providing rougher surfaces, edges, crevices, and water-retaining holes akin to natural rocky shores, thereby fostering biodiversity between the low and high tide zones (Jackson et al., 2022). These enhancements aim to improve habitat for native species that struggle to attach to smooth, flat surfaces common on seawalls, often dominated by nuisance and invasive species (Jackson et al., 2022).

This installation is part of broader efforts to enhance the reclaimed area and city gateway, which also involved the removal of over 400 truckloads of old demolition materials by Wellington City Council. Similar tile types have been successful on seawalls in Sydney and Singapore and were trialled in Auckland as part of the World Harbour Bivalve Restoration Project (Locke et al., 2019; MacArthur et al., 2019; Strain et al., 2021). However, the Wellington Kete Tiles marks one of the first larger-scale applications in Aotearoa New Zealand as a permanent project, offering a chance to test the approach in an area prone to strong wave action.

Holden Hohaia, a trustee of Taranaki Whānui, draws a parallel between traditional kete, woven from harakeke, used for gathering kai moana, and the hope that the structures and cavities in the concrete tiles will serve a similar function over time, becoming miniature habitats for sea life.

Ecological enhancement plans for the 430m-long rock revetment, devised by Tonkin and Taylor, also include using drilling equipment to create holes, crevices, and indentations in some of the rock rip-rap. Monitoring by the Greater Wellington Regional Council, in collaboration with Te Herenga Waka Victoria University of Wellington, will evaluate the efficacy of both approaches in promoting the growth of native marine species.Designers also considered the safety of penguins navigating between the sea and future nests in the revetment. Department of Conservation experts anticipate the embankment providing safe nesting spots for kororā (little blue penguins) (Jackson et al., 2022).

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Kete Tiles. Photo from Wellington City Council
References
  • Jackson, S., Cameron, M., & Paine, M. (2022). Marine habitat enhancement and fauna management at Cobham Drive, Wellington. In Australasian Coasts & Ports 2021: Te Oranga Takutai, Adapt and Thrive: Te Oranga Takutai, Adapt and Thrive (pp. 574-579). Christchurch, NZ: New Zealand Coastal Society.
  • Loke, L. H., Heery, E. C., Lai, S., Bouma, T. J., & Todd, P. A. (2019). Area-independent effects of water-retaining features on intertidal biodiversity on eco-engineered seawalls in the tropics. Frontiers in Marine Science, 6, 16. 
  • MacArthur, M., Naylor, L. A., Hansom, J. D., Burrows, M. T., Loke, L. H., & Boyd, I. (2019). Maximising the ecological value of hard coastal structures using textured formliners. Ecological Engineering, 142, 100002.
  • Strain, E. M., Steinberg, P. D., Vozzo, M., Johnston, E. L., Abbiati, M., Aguilera, M. A., … & Bishop, M. J. (2021). A global analysis of complexity–biodiversity relationships on marine artificial structures. Global Ecology and Biogeography, 30(1), 140-153.

Further resources:

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