Mataura River stop banks
In August 2022, an evaluation of the Mataura River stop banks by specialist engineers was received that identified concerns about their capacity.
The evaluation was part of the climate resilience works being undertaken, which included investigations by flood protection experts. The investigations highlighted that further work is required, urgently, to better understand the capacity and integrity of the stop banks. These investigations will include detailed geotechnical investigations and 2D hydraulic modelling.
Most of our stop banks are at least 30 years old and were designed to address flooding issues at the time. Challenges, such as increased and more extreme weather events as a result of climate change have put them under pressure.
There is now good information on the likely impacts of climate change and we also know that we are in a cycle of increased flood events and high river flows as a result of the Interdecadal Pacific Oscillation, an oceanographic/meteorological phenomenon.
The February 2020 floods on the Mataura River have contributed to the stop bank situation and, while some remedial work was carried out soon after this, more work will need to be done.
Our catchment team is gathering the necessary information, including geotechnical data and hydraulic modelling, to help us establish the best options to protect Gore, Mataura and Wyndham. We already have a work plan underway for the Gore stop banks, but the Mataura situation is a bit more complicated for a number of reasons, including the proximity of the stop bank to the road. We are working on securing more data so that we can be clear about the appropriate remediation options.
Read the complete Mataura flood protection flyer here.
Community safety – evacuation
Because the frequency of flooding events is likely to increase, we are working closely with Emergency Management Southland to take a precautionary approach to keeping the communities of Gore, Mataura and Wyndham safe.
This means that people living in these communities may need to be evacuated sooner and at a lower river level/flow than they have previously, while we work to better understand the current capacity of the stop banks.
Residents across all communities, as part of being prepared for emergencies, are encouraged to prepare for evacuation. Have a plan, gather supplies and get connected – go to the EMS website for more information (www.cdsouthland.nz/get-home-ready/). Being prepared will help to make any evacuation easier and less stressful.
In the event of a flood event, Emergency Management Southland (EMS) will make the decisions about when and if to evacuate and will lead any evacuation. EMS can provide advice to people to evacuate and once a state of emergency is declared by the mayor, EMS can make evacuation mandatory. Each event will be assessed on a case by case basis, as it is not possible to predict conditions for every situation.
We do have some factors working in our favour, including being able to predict how quickly flood waters travel. Our hydrological team will know up to 12 hours ahead of time, what the situation is likely to be around the catchment. We also know from experience during the 2020 floods that we can quickly and effectively evacuate these communities within a couple of hours.
Mataura River stop bank drop in sessions
We will be holding a number of drop-in sessions for people to come along and ask questions to help them better understand the current situation. These will be held In Mataura, Gore and Wyndham.
Mataura Senior Citizens Centre
- Friday 19 August 11am-1pm
- Thursday 1 September 4-6 pm
Gore District Council
- Monday 22 August 11am-1pm
- Friday 2 September 4-6pm
Wyndham Community Centre
- Friday 26 August 4-6pm
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