Early warning: Enhancing Canterbury's flood warning system
With heavy rain and rising river levels across Waitaha Canterbury, and the recent flood warnings issued for the Hurunui and Kaikōura districts; Environment Canterbury’s Flood Warning System steps in when weather events like these happen, helping to save lives, protect property, and limit damage.
As a Regional Council, it’s our responsibility to deliver a flood warning system that accurately informs the community and response agencies of incoming floods so they can prepare and respond effectively.
Through our hydrometric network, we monitor approximately 270 rainfall and river sites across the region. Using satellite, radio and mobile phone communication, we transmit data from the field back to our offices where it is then displayed on our website and other platforms. Our team uses this information to track river flows and rainfall, analyse trends, and issue flood warnings or advisories to prepare the community for incoming weather events.
We also share our data and analysis with other key agencies through our role in Civil Defence. This helps councils and emergency services plan local responses to a potential incoming flood.
It’s vital that our flood warning system is resilient, stable, and accurate, and we’re currently doing a comprehensive review of all our systems and technology to ensure Canterbury Regional Council (Environment Canterbury) delivers the best possible service for Waitaha Canterbury.
Community Preparedness and Response to Hazards Core Service Lead, Councillor Ian Mackenzie emphasises that these weather events underscore why we continue to strengthen and monitor the flood warning infrastructure.
“Extreme weather is becoming more frequent for our communities, and events like the one experienced recently reinforce the importance of a reliable, resilient early warning system. Our ongoing improvements help ensure we can deliver accurate, timely information to help communities protect themselves, their whānau, and their livelihoods,” Cr Mackenzie said.
How does the flood warning system work?
Flood warnings happen across different timescales, and our system is designed to operate at every stage, before and during a flood.
Before a flood, we:
- Operate and maintain monitoring equipment at 268 rainfall and river sites across the region.
- Monitor river levels and rainfall and send real-time data to our offices.
- Collaborate with Metservice and staff from various agencies across the region.
- Our River Engineers and Scientists review and analyse the data.
- Plan for many possible flood scenarios, modelling where floodwater is likely to flow which informs the design of flood protection infrastructure.
- Talk to communities living near rivers to help them understand flood risks and their local flood protection scheme.
- Have staff on call 24/7 tasked with monitoring river flow and weather conditions, ready to ramp up a response when required.
During a flood we:
- Have dedicated knowledgeable staff who actively manage the flood defence systems (such as stop banks and floodgates), make field observations and give advice on the performance of the assets protecting the community.
- Our technology measures and transits rainfall and river level data in real-time.
- Stand up a 24/7 Flood Control team that monitors river levels to understand flows and share timely warnings and information during a weather event.
- Our team follows clear plans to respond to various conditions and works closely with partner agencies to give them the best information.
- Share what we know with the community through flood warnings, advisories, and continuous monitoring data on our website.
All of these actions work together to create a flood warning system, and we need to make sure this system is as robust as possible to help us inform and prepare communities across Waitaha.
To deliver this complex and critical programme of work, we have an experienced team focused on improving every part of the system - from site infrastructure and networks to data management and flood modelling.
What we’ve achieved so far
Here are just a few examples of what the team has been working on:
- Improved our flow forecasting models which predict river flow based on forecast rainfall.
- Expanded and improved the accuracy of flood inundation modelling across the region.
- Updated and expanded 24/7 roles to help protect communities by ensuring all parts of the flood warning system work together effectively.
- Since July, we have upgraded 23 sites and installed two new ones.
- Expanded and promoted our flood warning text service, which provides early warning alerts to people in high-risk flood areas to rising river flows.
- Checked priority sites to ensure equipment is working reliably.
- Flood room communications are being upgraded as part of ongoing improvements to deliver faster response times.
- Reviewed all issues with our sites and digital systems during flood events since 2020 and taken action to fix problems.
- Put in place a new process to be digitally ready ahead of events to ensure our website and digital systems can stay operational during high website traffic.
- Developed a diagnosis tool to continuously monitor the status of the network and rapidly pinpoint where issues are.
What’s next
As we move into the new year, our focus remains clear: build resilience through new equipment, clearer processes, better communication and more robust backend systems.
To do this we need to work with our local territorial authorities as well as other regional councils, science and engineering experts, local iwi and central government to make sure we have a system that meets the needs of all our communities. This will build collective resilience across Aotearoa and strengthen our system overall.
As we work to upgrade our system and service, we will continue to deliver timely, accurate, and actionable flood risk information to communities, helping people protect themselves and their whānau, property and livelihoods.
With extreme weather becoming more frequent, these upgrades are critical to keeping communities safe now and for the future.