Ashley Rakahuri flood resilience project

Over the next several years, we’re planning to create new flood resilience measures along the 22km section of the Ashley Rakahuri that runs between the Ōkūkū River and Waikuku Beach.

Our goal is to strengthen flood resilience for Rangiora, Kaiapoi, Waikuku, and surrounding areas.

We want your input on the initial options we're considering. Please give your feedback by 5pm on 31 July 2026. We’ll be considering your feedback as it comes in, and there will be further opportunities to have your say as the project progresses.

Why we’re doing this work now

Early flood protection works on the Ashley Rakahuri started in the 1930s. The existing stopbank scheme has protected the district for around 70 years, but over that time, the flood risk has increased.

  • Recent events, such as the Auckland Anniversary floods and Cyclone Gabrielle, have demonstrated that extreme rainfall and flooding are happening more often and causing greater damage than in the past. Scientific evidence shows these types of events are becoming more frequent and intense.

  • There are now more people, homes, businesses and infrastructure located within the Ashley Rakahuri floodplains. This means the consequences of flooding are higher than they were when the scheme was first built. View our flood modelling maps to see the areas that could be affected during a 1‑in‑500‑year flood event.

  • Our modelling shows there is a risk of floods breaking out at different points along the river. We want to ensure our flood protection reflects today’s risks and that they are fit for the future.

Our approach

As we follow the Ashley Rakahuri from its confluence with the Ōkūkū River to the coast, the river changes. Flood breakouts can travel in different directions and have different impacts in different places. That's why we're looking at the river in three reaches, each requiring different ways to manage breakout flooding risk.

Reaches:

  • Ōkūkū confluence → Rangiora Railway Bridge

  • Railway Bridge → SH1 Bridge

  • SH1 → the ocean


What options we're considering

We’re considering a range of possible solutions that may be combined. Different approaches may be needed for different parts of the river. These include:

  • Upgrading or modifying the existing primary stopbank
  • One or more secondary stopbanks
  • Managed floodways
  • Stopbank retreat
  • Berm vegetation management
  • Wetland creation / room-for-the-river approaches
  • Gravel management

At this early, investigative stage of the project, we have no preferred option/s. Your feedback will help select a preferred option by correcting our assumptions and highlighting unintended consequences. This will be balanced with other criteria such as safety, practicality for land use, environmental and cultural outcomes, feasibility and cost.

Have your say on flood resilience options

Over the next several years, we’re planning to create new flood resilience measures along the 22km section of the Ashley Rakahuri that runs between the Ōkūkū River and Waikuku Beach.

Our goal is to strengthen flood resilience for Rangiora, Kaiapoi, Waikuku, and surrounding areas.

We want your input on the initial options we're considering. Please give your feedback by 5pm on 31 July 2026. We’ll be considering your feedback as it comes in, and there will be further opportunities to have your say as the project progresses.

Why we’re doing this work now

Early flood protection works on the Ashley Rakahuri started in the 1930s. The existing stopbank scheme has protected the district for around 70 years, but over that time, the flood risk has increased.

  • Recent events, such as the Auckland Anniversary floods and Cyclone Gabrielle, have demonstrated that extreme rainfall and flooding are happening more often and causing greater damage than in the past. Scientific evidence shows these types of events are becoming more frequent and intense.

  • There are now more people, homes, businesses and infrastructure located within the Ashley Rakahuri floodplains. This means the consequences of flooding are higher than they were when the scheme was first built. View our flood modelling maps to see the areas that could be affected during a 1‑in‑500‑year flood event.

  • Our modelling shows there is a risk of floods breaking out at different points along the river. We want to ensure our flood protection reflects today’s risks and that they are fit for the future.

Our approach

As we follow the Ashley Rakahuri from its confluence with the Ōkūkū River to the coast, the river changes. Flood breakouts can travel in different directions and have different impacts in different places. That's why we're looking at the river in three reaches, each requiring different ways to manage breakout flooding risk.

Reaches:

  • Ōkūkū confluence → Rangiora Railway Bridge

  • Railway Bridge → SH1 Bridge

  • SH1 → the ocean


What options we're considering

We’re considering a range of possible solutions that may be combined. Different approaches may be needed for different parts of the river. These include:

  • Upgrading or modifying the existing primary stopbank
  • One or more secondary stopbanks
  • Managed floodways
  • Stopbank retreat
  • Berm vegetation management
  • Wetland creation / room-for-the-river approaches
  • Gravel management

At this early, investigative stage of the project, we have no preferred option/s. Your feedback will help select a preferred option by correcting our assumptions and highlighting unintended consequences. This will be balanced with other criteria such as safety, practicality for land use, environmental and cultural outcomes, feasibility and cost.

Have your say on flood resilience options

Questions and answers

Questions about the project? Ask them here. We aim to reply to questions within five business days.

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Page last updated: 01 Apr 2026, 05:47 PM