11 September

The Hawke's Bay Regional Council (HBRC) has released findings from three independent reviews into the June 2024 flooding in Wairoa. These reviews, commissioned by the Council, aim to understand the event's impacts and identify crucial measures to develop Wairoa’s flood resilience.

These expert reviews supplement the findings of Government-commissioned review – lead by Mike Bush – into the wider framework for HBRC’s management of the Wairoa River mouth.

We commissioned three independent reviewers:

• Graeme Campbell, Strategic Advisor Flood Resilience, Te Uru Kahika – Regional and Unitary Councils Aotearoa, undertook a brief review of the procedures we used and the actions we took about the opening of the Wairoa River Mouth over the period 21 -30 June 2024.
• Tonkin + Taylor, an environmental and engineering consultancy, undertook a technical analysis of the flooding event.
• Kyle Christensen, an Independent Consultant with over 20 years’ experience in river and stormwater engineering, undertook a review of the management of the Wairoa River mouth in the lead up to the weather event of 26 June 2024 and the decisions made by us about whether the bar should be mechanically opened and, if so, when.

Hawke's Bay Regional Council Chair Hinewai Ormsby acknowledged the immense challenges faced by the Wairoa community. "We've witnessed the incredible strength, resilience, and unity of the Wairoa community during and after this unprecedented event and following what occurred during Cyclone Gabrielle. We are deeply committed to standing by you every step of the way as we work together to make Wairoa safer and stronger," she said.

One of the key purposes of these reviews was to understand what occurred during this event so that the risk can be managed into the future. Hawke’s Bay Regional Council Chief Executive, Nic Peet said “the reviews are clear that the flooding in June was the result of high rainfall, rising river levels, spring tides, storm surge as well as the position of the bar. These factors coincided to create 1-in-250-year event. We heard from residents that this type of flooding had not been experienced in living memory, and this is why.

“Even if the bar could have been opened, the flooding may not of have been prevented. However, all four reports also indicate that there are things that HBRC can improve with regard to its management of the Wairoa River mouth.”

Chair Ormsby, said “these reports, together with the recommendations of the Hawke’s Bay Independent Flood Review mean the Council has clear recommendations for action. These reports confirm that there is no simple solution. There are interim steps that we need to act on immediately to change now we manage the Wairoa river mouth, while the more comprehensive measures will take more time to put in place.”

Dr. Peet said steps have already been taken to improve monitoring of the river bar and Council staff have been working with a local contractor to improve the current condition of the river bar. “Working with a local contractor, we have lowered the existing beach crest and created an overflow trench in the Wairoa Bar, 500m to the east of Pilot Hill. The trench is to allow the river to overflow the bar in a rainfall event and also allows a new opening to be completed more quickly, when conditions allow.”

“Further, we are making sure that we have a comprehensive operational plan in place for the management of the bar and are working to ensure that we have enduring and clear arrangements in place with a local contractor.”

“A number of cameras will be installed along key points on the river, and we have been working with WDC staff on the locations of these. We will also carry out bathymetric (river depth) surveys, when conditions allow”.

However, all of the reports, including Mike Bush’s review, are clear that the mechanical opening of the bar should not be the only measure to manage Wairoa’s flood resilience around the river bar. “In future, Wairoa cannot depend on bar openings as the only method for preventing flooding in the lower part of the town,” Dr Peet said. “As sea level rises and storms become more intense, further options are needed. We are committed to investigating these together with Wairoa District Council (WDC), Tātau Tātau o Te Wairoa and the Crown.”

Chair Ormsby said she is acutely aware of the immense challenges faced by the Wairoa community and is committed to ensuring Regional Council does everything it can to enhance Wairoa’s flood resilience.

“It is critically important that council collaborates closely with the community to manage the river bar effectively and mitigate flood risks. Your local knowledge and experiences are invaluable in this process.”

Chair Ormsby said: "Together with Tatau Tatau o te Wairoa, the District Council, central Government, the Crown Manager, and the people of Wairoa, we will diligently find the right longer-term solutions, not just for managing the river mouth better but also for ensuring that the entire Wairoa River flood management system provides the best flood mitigation possible for the township."

"This journey will not be easy, and there will be some difficult conversations ahead and tough decisions to be made. However, we pledge to you that the Regional Council will be at the table in the spirit of partnership and collaboration."

The full reports are available on the HBRC website: https://www.hbrc.govt.nz/our-council/june-2024-wairoa-flood-event

© Scoop Media