Woven mats / Uwhi (harakeke wet mats)

Figure 1 Te Arawa Lakes Trust Dive squad

  • Type of NbS: Management/social/political, Ecosystem Restoration, Ecosystem protection
  • NbS ecosystem type: Freshwater lake, spring, river 
  • Location: This nature-based solution can be implemented in roto (lakes), puna (springs), awa (rivers) and other fresh waterways across rural and urban locations.

NbS description:

Uwhi (harakeke weed mats) is a mātauranga māori-driven NbS using traditional ecological knowledge and methods to restore and protect roto (lakes), puna (springs) and other fresh waterways. The technique has been innovated and trialed by Te Arawa Lakes Trust since 2021. Uwhi have been made by local expert weavers with support of Te Roopu Raranga Ki Rotorua. They are woven from locally sourced harakeke, a native flax, which has been used by Māori for over 800 years. The 2.5 by 5m mats are laid down and secured to the lakebeds, stopping sunlight from reaching invasive weeds, preventing photosynthesis and therefore suppressing their growth. This allows for native aquatic plants and traditional mahinga kai such as kōura (crayfish) to repopulate the lakes. As the harakeke gradually breaks down it provides a nutrient base for the native seed growing water plants which are able to grow through the specific weave of the mats.

Relationship to Indigenous knowledge:

As tangata whenua (people of the land), Māori are kaitiaki (guardians), with the responsibility and right to oversee the mauri (well being, life force) of Pāpatuanuku (mother earth) and te taiao (the natural world). Central to this worldview is the interconnectedness between te taiao and te tangata (the people), whereby the health of the natural world ensures the health of the people. This is reflected in the concept of whakapapa, which is much more expansive than the western concept of genealogy. Whakapapa weaves all of existence together, across the human and more-than-human, into a complex web of intimate relationships,  forming the basis of Māori ways of being, knowing, and doing (Burgess & Painting, 2020). Through whakapapa, all of existence is whanaunga (kin), existing in a natural state of whanaungatanga: forming and maintaining close relationships (Burgess & Painting, 2020). As with many other indigenous knowledge systems, Māori do not view te taiao as a resource to own, extract and exhaust but rather see natural resources as taonga (treasured) and therefore to be cared for in order to uplift the mauri of all living things within this expanding web of whakapapa for past, present and future generations. The innovative creation and use of uwhi is driven by these te ao māori values and brings together mātauranga māori with western scientific knowledge, demonstrating the ways in which Traditional Ecological Knowledge (TEK) is responsive and adaptive to Te ao Huriri (the changing world).

Climate change benefits:

  • Increased water quality
  • Increased food production
  • Reduced pests or spread of weeds

The interlinked issues of climate change and biodiversity loss are two of the most urgent challenges that we as a species must grapple with (Varshney, K. Et al, 2022). Growing research and discourse identifies the vital need to protect and restore biodiversity in order to reduce the impacts of climate change, which in turn, has a destructive impact on biodiversity. 

Indigenous peoples and communities are on the frontline of experiencing the impacts of climate change. Climate justice is inextricably linked to social, cultural, racial and Indigenous justice (Paul, 2020). The ongoing process of colonisation has displaced and dispossessed indigenous peoples from their lands and their ways of knowing, doing and being in close relation with the natural environment. Colonisation is a key factor in the way our environment has been managed (Paul, 2020) and as such has been a leading force contributing to climate change, loss of biodiversity, degradation of ecosystems and habitats. 

The degradation of Te Arawa lakes and fresh waterways is an example of this nexus of climate justice and indigenous justice. The invasive weeds that have significantly impacted the quality and biodiversity of the wai is a direct result of colonisation. These weeds were introduced in the 1950s when water from aquariums were poured into Lake Rotoiti and Lake Tarawera. The weeds subsequently colonised the lakes’ ecosystems, devastating the native aquatic plants and species. Almost 99% of kōura (native crayfish), which are considered tāonga, have been wiped out. In turn, the presence of invasive weeds will worsen with climate change further degrading ecosystems and habitats. 

Te Arawa Lake Trust’s strategy of using uwhi for ecological restoration and protection is part of their larger, holistic climate change strategy, Te Ara Ki Kōpū, led by Te Urunga o Kea: Te Arawa Climate Change Working Group. The strategy aims to ensure the resilience and survival of their people as the impacts of the changing climate escalate. Central to this kaupapa is weaving together mātauranga māori with contemporary knowledge through innovation and collaboration.  Whakapapa is the foundation of this strategy, in which generations of knowledge shows the way forward (Te Arawa Climate Change Strategy). 
A key climate change impact for indigenous peoples’ is the issue of food security and food sovereignty. Connection to locally grown food and self-determination over food production is central to indigenous communities across the globe. Food sovereignty has been defined by the International Planning Committee for Food Sovereignty as: “the right of peoples to healthy and culturally appropriate foods produced through ecologically sound and sustainable methods, and their right to define their own food and agriculture systems” (Ritchie, 2021). A key outcome for Te Arawa’s uwhi project is to return traditional mahinga kai to the lakes and to the people.

Societal / socio-cultural benefits:

  • Rights / empowerment / equality / tino rangatiratanga
  • Education and knowledge
  • Aesthetic and artistic inspiration
  • Water quality and security
  • Food security 

Te Arawa iwi (tribe) have a long standing physical and spiritual connection to the Te Arawa Lakes since settling on the rohe (land) and are therefore te hunga tiaki (kaitiaki) of the mauri of the lakes and surrounding whenua (Te Arawa Values Framework). The uwhi project has been a significant milestone for Te Arawa as a place-based approach led by mātauranga māori that has empowered local whānau, hapū and iwi knowledge and values (Te Arawa Lakes Trust).  This type of place-based approach that empowers local communities who have ancestral connections to the land leads to longer term intergenerational success for sustainable management of ecological systems (Carter, L 2019).

Not only has the project created jobs for the local community but is also keeping toi māori (māori arts) alive and bringing it into a new, innovative space that intersects with contemporary scientific knowledge. The mats are made from parakoka, the discard from preparing flax for whaariki, kete and piupiu. Because whaariki is the name for a mat usually used in doors, with a much finer weave, the project team created a new name for this underwater woven mat: uwhi. Different weaving patterns were tested in order to find the right type of weave to successfully suppress the weeds and allow for native plants to grow through.

Ecological and biodiversity benefits:

  • Decreased pests or spread of weeds
  • Habitat provision
  • Species maintenance
  • Increased fresh water quality

Indigenous knowledge of the land passed through generations is critical to restoring and protecting ecosystems and biodiversity. Native plants and species are crucial to the health of lakes and waterways. 

The restoration and protection of biodiversity through aquatic weed management leads to the enhancement of ecosystem services of the Lakes and fresh waterways.  

Technical requirements:

Te Arawa Lakes Trust holds the intellectual property rights for this NbS with the vision of offering it to other rohe across Aotearoa therefore the technical requirements will be determined and led by Te Arawa tōhunga and expert weavers who have innovated and tested this mātauranga Māori driven strategy.

Issues and Barriers: 

Uwhi is still a new NbS and has so far only been implemented and tested in Te Arawa lakes and waterways and as such there is still limited research and published data. The results so far however have shown that it is an effective way to reduce aquatic invasive weeds.


Using mātauranga Māori values-driven management supports community-driven nature-based solutions that are best suited to the people as well as the environment. There is significant potential in implementing this innovative NbS across wai in Aotearoa,  supporting indigenous expertise and knowledge as well as working with a locally grown natural and regenerative resource.

Financial case:

Uwhi is a low-lost, locally sourced and produced native alternative to imported hessian mats. It offers longer term economic benefits by reducing the need for costly pest control. Another financial benefit is the potential for job creation in providing relevant mahi (work) for local communities. 


  • Clapcott, J., Ataria, J., Hepburn, C., Hikuroa, D., Jackson, A. M., Kirikiri, R., & Williams, E. (2018). Mātauranga Māori: shaping marine and freshwater futures. New Zealand Journal of Marine and Freshwater Research52(4), 457-466.
  • Varshney, K.; Pedersen Zari, M.; Bakshi, N. Carbon Sequestration and Habitat Provisioning through Building-Integrated Vegetation: A Global Survey of Experts. Buildings, 2022, 12, 1458. https://doi.org/ 10.3390/buildings12091458  
  • Carter, L. (2018). Indigenous Pacific Approaches to Climate Change: Aotearoa/New Zealand. Springer.
  • Ritchie, I. P. (2021). Food Freedom and Community. Te Ra Aroha Press
  • Paul, J. (2020). Climate Justice is Indigenous Justice. In T.Doig (Ed.) Living with the Climate Crisis: Voices from Aotearoa (pp.200-212). Bridget Williams Books. 
  • Burgess, H., & Painting, T.K. (2020).Onamata, anamata: A whakapapa perspective of Māori futurisms. In (Eds.) A. Murtola & S. Walsh. Whose Futures? (pp. 205-233). Economic and Social Research Aotearoa Tāmaki Makaurau Auckland Aotearoa New Zealand.

Further resources:

Case study:

Rotorua Uwhi, Te Arawa Lakes, Aotearoa New Zealand 2021

Uwhi. Photo/Mark Taylor