The report of the Hawke’s Bay Independent Flood Review into Cyclone Gabrielle and its impacts on Hawke’s Bay was officially received today (Wednesday, 24 July) by Hawke’s Bay Regional Council.

Council Chair Hinewai Ormsby noted that receiving the report was an emotional moment for council.

“Council is hugely grateful to all those who shared their experiences with the panel and contributed to its picture of impacts on our region.”

“We want to thank the review panel - Dr Phil Mitchell (chair), Bernadette Arapere and Kyle Christensen – for their complex and elaborate work over the past year. We greatly appreciate their efforts and look forward to thoroughly considering and working through the panel’s recommendations.

“As Hawke’s Bay and indeed New Zealand works out how to deal with the effects of climate change and more intense storms, learning from our recent experiences is critical. The review has identified a range of important learnings and provides valuable recommendations.

““What all the reviews have told us is that the way we have worked for the past 30 years can’t be the way we work for the next 30 years. That journey has already begun and there is a massive amount of work ahead.”

“As a Council we are already in the design phase for the Category 2 projects (to restore areas to Category 1 – where there is no intolerable risk to life at the property), upgrading pumpstations and managing gravel in the major rivers. We are also assessing further upgrades to the flood mitigation network. We are increasing work to reduce hill country erosion and we have begun writing the next Regional Policy Statement. We have upgraded our telemetry system to make it more resilient.

“There are difficult and challenging conversations to come across local Government, mana whenua and communities about how we plan for and manage floods from events like Gabrielle. Yes challenging, but together we will need to work out how we manage water in a more unpredictable environment and storms that will test and push beyond our current infrastructure capabilities. However, working towards a greater resilient for our region is our top priority.

“There is more to come as we adapt to a changing climate – those discussions need to be founded on finding the right mix of local, technical and national knowledge – we must leave no stone unturned.

Fact Sheet – HB Flood Control Schemes

Regional Council currently manages 27 flood control and drainage schemes throughout the region to reduce the risk of flood and erosion damage.

• We maintain networks of stopbanks, hydraulic structures and pump stations and manage the river, stream, and drainage channels to ensure they work as expected during floods. This includes gravel management to maintain flood capacity and allocation of gravel from riverbeds.

• The Hawke’s Bay flood control schemes:

o The Heretaunga Plains Flood Control Scheme (HPFCS)

o The Upper Tukituki Flood Control Scheme (UTTFSC)

• The Hawke’s Bay flood drainage schemes:

o These are small schemes that cover Hawke’s Bay from Porangahau to Wairoa

• During Cyclone Gabrielle in February 2023 the intense rainfall in a short period was more than our river management network was designed and built to manage.

o The Glengarry site recorded 546mm of rainfall, the most of all the region’s sites, with almost 400mm falling in 12 hours.

o The eastern area of Wairoa received more than 500mm of rain.

o 320mm fell in the Newstead site which was about one-third of the area’s annual rainfall. o Nearly 6 kilometres of stopbanks across the 248-kilometre network was breached and a further 28 kilometres weakened.

• Prior to Cyclone Gabrielle: We had already started work to accelerate flood resilience, including strengthening the stopbank in Taradale which helped protect that community from flooding.

• Post Cyclone Gabrielle:

o Council commissioned a review of the performance of its flood infrastructure during the event. The Hawke’s Bay Independent Flood Review (HBIFR) is due 24 July 2024.

o We also commissioned technical reviews of our two largest flood control schemes, Heretaunga Plains and Upper Tukituki. These are due in August.

• We have two substantial flood resilience work programmes underway:

o North Island Weather Event (NIWE) Flood Resilience Programme: part of the region’s Cyclone Gabrielle recovery package enabled by $203 million of Crown funding. Regional Council agreed to fund and additional $44.15 million for the work. This programme includes:

New flood protection schemes in Wairoa, Whirinaki, Waiohiki, Omāhu, Pākōwai and

Pōrangahau

Upgraded pumpstations at Awatoto, Brookfields and Pākōwhai

o Resilient River Communities Programme: This programme – due to be completed in 2025, subject to scheme review recommendations – includes geotechnical investigations and design work for Brookfields Lower, Raupare, Pākōwhai Park and East Clive, undertaking river erosion control work at Farndon Road, and a final tranche of gravel extraction from the Upper Tukituki catchment.

Backgrounder – Flood control in Hawke’s Bay

Hawke’s Bay lies predominantly on coastal flood plains surrounded by steep and highly erodible hill country. The plains are traversed by three main rivers – the Tukituki, Ngaruroro and Tūtaekurī. The Wairoa River in Northern Hawke’s Bay travels through the Wairoa township.

The river plains have been prone to flooding since pre-European times. Early settler William Colenso noted in his letter outlining his experiences of floods at the Mission Station (near modern-day Clive) – including one on June 25, 1847 – that “the wise old Māori well knew of those floods, and in a measure were well prepared for them.”

Despite his warnings, as European settlers took up more land during the 1860s in Meeanee and Pākōwhai for agriculture, they were caught out in 1867. From Mataruahou (Napier Hill) all that could be seen of Meeanee and Pakowhai was “a waste of waters, relieved only by settlers’ houses and the clumps of trees which indicated the site of a homestead.”

Individual settlers started to make their own flood protection measures by either planting willows or building stopbanks – and this had the unintended consequence of pushing water to other properties and flooding them.

A more comprehensive approach to river flood control was sought by forming four river boards: Taradale (1877), Clive (1891), Meeanee (1894) and Pukahu (1895). These boards were described by local settlers as “dysfunctional.”

The next major flooding event in 1893 saw Clive inundated when the Tukituki broke its banks near the Black Bridge.

Only four years later, in 1897, the Good Friday floods devastated Clive again, as well as Napier and Hastings.

The river boards were abandoned in 1910 for one body – the Hawke’s Bay Rivers Board. It requested multiple engineering studies for flood protection.

It was Esk Valley’s turn in 1924 and 1938 when major flood waters and silt caused significant damage. The main land use was then agriculture, and apart from homesteads, the silt was left in place, and grass re-sown.

The Hawke’s Bay Rivers Board accomplished the diversion of the Tutaekuri from the Ahuriri lagoon in 1936 to a mouth at Waitangi.

The Hawke’s Bay Catchment Board took over from the Hawke’s Bay Rivers Board in 1944, and their scheme to divert the Ngaruroro from its mouth at Clive to a shared one with the Tutaekuri was finally completed in 1969.

Major stopbank construction was undertaken along the three rivers in the 1960s and 1970s. The Hawke's Bay Regional Council has had the responsibility for flood protection since 1989.

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