Success story

Water and Sediment Source Mapping for the Waipaoa Catchment

Ngā Ariki Kaipūtahi have ancient ancestral connections to the middle and upper reaches of the Waipaoa River, the Mangatū River, and the Urukokomuka Stream. They hold mana whenua rights primarily in the original number one Mangatū Block region and in the neighbouring Manukawhitikitiki, Whatatutu, Mangataikapua, and Rangatira blocks near the confluence of the Waipaoa and Mangatū Rivers.

Given the limited data for the catchment, Ngā Ariki Kaipūtahi were keen to gather basic information to help identify and understand mitigation options for erosion reduction, water and sediment sources, and the impacts of different land uses on freshwater in the rohe. They also wanted to know about the various sediment and freshwater outlets and interactions within the catchment.

This information was sought as a key input into the Taua o Ngā Ariki Kaipūtahi Seven Generation Environmental Plan, a document that will influence how the whenua is managed into the future.

“Nga Uri Taniwha, Te Taiao o Nga Ariki Kaipūtahi is our 7-generation vision to tend, guard and restore the mana mauri of the mountains, rivers and forests of the Mangatū through nourishing the whakapapa of our systems ecology.” – says Matawhero Lloyd, Kaiwhakamarumaru (Protector) and Chief Executive Officer of the Taua o Ngā Ariki Kaipūtahi.

Watch here to understand more about Ngā Ariki Kaipūtahi and the significance of their connection to the mauri of the Waipaoa River.

Through A2E, experts from WSP New Zealand provided their advice through a range of activities, ranging from a review of catchment data, the development of a water and sediment map, and stakeholder engagement and facilitation. A site visit allowed on 17th July 2024 allowed further validation and explanation of the findings to key iwi representatives.

“Sediment management is a key issue for the Waipaoa catchment with active sediment sources spread over the top of the catchment. With the rohe of Ngā Ariki Kaipūtahi located near the sources and active river sections of the catchment, community-based understanding of the sediment transfer patterns along the streams and their causes is crucial”, says Niraj Tamang, geomorphologist.

Our expert’s findings were also helpfully summarised into a visual document (pictured below), to help distil otherwise technical information into an easy-to-understand format. A public report (PDF, 5.77 MB) is available with the technical details of the work.

Dr Sandra Velarde shares that combining technical skills with cultural understanding and science communication made a big impact for all involved.

“The needs from users, particularly iwi and hapū, are complex and often require multiple experts. We are pleased with the result of taking a different approach and tailoring our support to the needs of Ngā Ariki Kaipūtahi,” says Sandra.

The information provided through A2E has helped strengthen the community knowledge for catchment planning and management.

Due to A2E’s support, Ngā Ariki Kaipūtahi now have the building blocks to understand the impacts of land uses on freshwater in the rohe, focusing on sediment. This information means they can actively work towards sediment reduction and the restoration of Te Mana o te Wai in the Waipaoa catchment.

The information received has also identified other potential focus areas, like mahinga kai, wetland management, and conversion from clear fell forestry to mānuka, agroforestry or native forest carbon sequestration for Ngā Ariki Kaipūtahi to pursue in future work.

The advice report recommends:

• developing strategies that consider current water and sediment in land use planning and infrastructure development,
• regular monitoring and management of water quality,
• involving the local community in monitoring, reporting and improved land use practices,
• ensuring the inclusion of the local knowledge of mana whenua in freshwater management actions.

The findings of this work can be leveraged to support the development of action-oriented catchment management plans.

Ngā Ariki Kaipūtahi sharing the visual summary of the freshwater mapping results for the Waipaoa catchment.

Waipaoa catchment site showing the washed-out bridge on the Waipaoa River near the confluence with the Mangatū River.