A small, flood-prone Northland community has withstood a 10-year rainfall event, thanks to new flood protection works led by Northland Regional Council.
Around 300ml of rain fell on the Far North’s Matangirau catchment during Ex-Tropical Cyclone Tam, the most rain recorded in the area in a decade and almost twice the rainfall recorded across Northland.
Flood protection measures were installed last year at Matangirau as part of the $5.735 million Flood-Resilient Māori Communities and Marae project.
The project – funded by the Local Government Flood Resilience Co-Investment Fund and Council – aims to reduce flood risks for the flood-affected Māori communities of Kawakawa, Otiria-Moerewa, Kaeo, Matangirau, Whirinaki and Punuruku and 35 marae across Te Tai Tokerau.
Local resident, Robert Rush said that prior to the flood works, his whare was always the first to flood during heavy rainfall.
“It’s been a work in progress, especially showing our whānau that the council were only there to help and not to steal our land,” Mr Rush said.
“We’ve had stop banks and river works done around our homestead and it hasn’t flooded since.
“We also had some work done just a couple of weeks before ex-Cyclone Tam, which was perfect timing because we didn’t flood during that time either, nor did my grandfather’s house which is near the new marae.”
NRC Te Ruarangi (Māori and council working party) Whangaroa hapū representative and Matangirau haukainga, Nyze Manuel agreed the benefits of the flood works were obvious.
She said the mahi of Te Ruarangi had also played a critical role in the activation and front line of Māori communities during these times.
“Well we’re not under water, so that’s awesome!” Manuel said.
“Through our Te Ruarangi network we were able to get out communications to people about the weather in a fast and efficient way.
“And as more flood works are done by NRC, we’ll see less flood water in these vulnerable areas.”
Matangirau’s flood mitigation is based on an engineering method called ‘floodway benching’ designed to reduce flood risk for homes and the marae upstream of the Wainui Road Bridge.
A 1960s rebuild of the bridge – which raised the bridge and approaches by about two metres above the existing flood plain – unintentionally worsened flooding by creating a ‘detention dam’ effect during heavy rainfall, capturing and holding excess water during heavy rainfall events.
The new benching works aim to reverse this damage by giving floodwaters more space to spread out, allowing more water to flow under the bridge. This approach, used successfully in Awanui, maintains the river channel while adding a higher, wider ‘bench’ for safer floodwater flow.
Northland Regional Council Rivers Manager, Joe Camuso said the recent weather event had proven the value of investing early in communities like Matangirau.
While it wasn’t a ‘miracle’ cure for flooding, Mr Camuso said it had made a significant improvement on the impact of heavy rainfall to the area.
“What we’re seeing now is the flow regime is much more efficient, so we’re seeing more water flowing under the bridge, which means less flooding during large rainfall events,” he said.
“While this is great, it is only built to withstand up to a 50-year flood event, of which there is only a two per cent likelihood each year.”
Flooding remains one of Northland’s most damaging and frequent natural hazards, impacting social, economic, and cultural wellbeing.
