Flooding processes defended
Selwyn District Council and Environment Canterbury have defended how they responded to the major flooding in the district early last month.
Mayor Sam Broughton and Environment Canterbury chair Craig Pauling have told Emergency Management Minister Mark Mitchell the flooding infrastructure held up, and the processes to manage flooding were up to standard.
They were responding to a letter from Mitchell sent to councils across New Zealand asking them to have a 'frank and honest' discussion about responding to flooding.
In his letter he highlighted the flooding in Canterbury, where parts of Selwyn and Banks Peninsula were hit hard.
"No stopbanks were breached or overtopped, and although drainage schemes were overwhelmed in places, they behaved as expected with water entering known ponding areas,' Broughton and Pauling said in a letter sent to Mitchell.
The district saw two months of rainfall fall in about 48 hours, causing a large amount of flooding, particularly around Ellesmere and Tai Tapu.
A particular concern among the community was whether Te Waihora/Lake Ellesmere could have been opened ahead of the flooding to reduce the impact.
Broughton and Pauling told Mitchell even if the lake could have been opened, it would likely have made little difference.
'Unfortunately, sea conditions prior to the event were not favourable, and any opening attempt would have been unsafe and unsuccessful. Had an opening attempt been made a week earlier, it would have closed quickly and likely would have had little effect on water levels during the event.'
It was noted in the letter that ECan wants the Government to continue to assist with funding for telemetry to monitor river levels and flows.
"To further support upgrades and strengthen resilience, co-funding with central Government has been sought within the Regional Infrastructure Fund to further accelerate our work.'
As part of its continued review of the May floods, the district council is paying particular attention to Doyleston, which was one of the worst-hit areas in the district.
On Sunday, council staff met with Doyleston residents to get local knowledge of locations that may have contributed to the flooding.
Staff said it would use that information to establish the next steps for the settlement.
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Otago Daily Times
a day ago
- Otago Daily Times
Flooding processes defended
Selwyn District Council and Environment Canterbury have defended how they responded to the major flooding in the district early last month. Mayor Sam Broughton and Environment Canterbury chair Craig Pauling have told Emergency Management Minister Mark Mitchell the flooding infrastructure held up, and the processes to manage flooding were up to standard. They were responding to a letter from Mitchell sent to councils across New Zealand asking them to have a 'frank and honest' discussion about responding to flooding. In his letter he highlighted the flooding in Canterbury, where parts of Selwyn and Banks Peninsula were hit hard. "No stopbanks were breached or overtopped, and although drainage schemes were overwhelmed in places, they behaved as expected with water entering known ponding areas,' Broughton and Pauling said in a letter sent to Mitchell. The district saw two months of rainfall fall in about 48 hours, causing a large amount of flooding, particularly around Ellesmere and Tai Tapu. A particular concern among the community was whether Te Waihora/Lake Ellesmere could have been opened ahead of the flooding to reduce the impact. Broughton and Pauling told Mitchell even if the lake could have been opened, it would likely have made little difference. 'Unfortunately, sea conditions prior to the event were not favourable, and any opening attempt would have been unsafe and unsuccessful. Had an opening attempt been made a week earlier, it would have closed quickly and likely would have had little effect on water levels during the event.' It was noted in the letter that ECan wants the Government to continue to assist with funding for telemetry to monitor river levels and flows. "To further support upgrades and strengthen resilience, co-funding with central Government has been sought within the Regional Infrastructure Fund to further accelerate our work.' As part of its continued review of the May floods, the district council is paying particular attention to Doyleston, which was one of the worst-hit areas in the district. On Sunday, council staff met with Doyleston residents to get local knowledge of locations that may have contributed to the flooding. Staff said it would use that information to establish the next steps for the settlement.
Otago Daily Times
26-05-2025
- Otago Daily Times
Mitchell wants answers on Selwyn flood response
Emergency Management Minister Mark Mitchell is urging councils to have a frank and honest assessment of how to mitigate flooding. Mitchell has written to all councils asking them to review current decision-making processes around flood protection and control and report back by next Friday. 'As you will be aware, there has been heightened public interest in how regional and local authorities have managed flood protection and control works during, and in the lead-up to significant weather events,' Mitchell wrote. 'Even when local authorities and staff have done exceptional work to respond to events, the perceived inability to effectively manage the flood protection schemes and waterways has contributed in some places to a lack of public trust in the emergency management system's ability to prepare for and respond to significant weather events.' The letter specifically mentioned Te Waihora/Lake Ellesmere and Lake Forsyth. In the aftermath of flooding caused by two months' worth of rainfall in eastern Selwyn over 48 hours, debate has emerged over whether opening Lake Ellesmere earlier could have reduced the damage. Environment Canterbury chair Craig Pauling told Selwyn Times it was in the process of preparing a response to Mitchell. 'We are confident our opening decision-making processes are robust, but are planning to meet with representatives from Te Rūnanga o Ngāi Tahu and the Te Waihora/Lake Ellesmere consultation group soon to debrief and discuss future management approaches.' The opening of Lake Ellesmere is governed by the National Water Conservation (Te Waihora/Lake Ellesmere) Order 1990. Under the order, the lake can be opened anytime from April 1 to June 15 to assist fish passage. Otherwise it can be opened between April 1 and July 31, only when it reaches a water level of 1.13m. Selwyn Times recently reported community concerns about the increase in subdivisions worsening the impact of floods. Said Pauling: 'We're also working with our communities to review how we manage and fund flood and river resilience so we can strengthen and have appropriate infrastructure into the future.' Mitchell's letter also asked councils to identify any additional regulatory powers they may need. Pauling said ECan was considering this as part of its response. However, Mayor Sam Broughton said no additional powers were necessary. 'The council currently has a strong framework of legal instruments to respond to a weather emergency, and we are not looking for any additional legislative levers to enhance our response.' A Christchurch City Council spokesperson said staff were working on a response to Mitchell's letter and could not comment further until it was complete.
Scoop
22-05-2025
- Scoop
Spend Now To Reduce Flood Risk
Spending money now will save Kaikōura from facing the full effects of a damaging future flood, says Kaikōura District Council boss Will Doughty. The 7.8 magnitude earthquake in November 2016 dislodged a significant amount of gravel, which left the town vulnerable in a major flood, he said. Environment Canterbury (ECan) has been reviewing its gravel management strategy on rivers throughout the region, with submissions closing last month. While it was difficult to estimate how much money needed to be spent now, Mr Doughty said an event similar to a Kowhai River flood in 1993, which devastated the town, would have a significant long-term economic impact. Implementing a gravel management strategy to extract excess material would help maintain the natural flow of the river and reduce the likelihood of blockages or sediment build up. ''The wandering nature of the Kowhai River and the dynamic nature of the system is a key challenge when attempting to determine the response of the river to flood events,'' he said. ''The likely damage to the town would depend on the severity and duration of the flood event, but vulnerable infrastructure such as roads, bridges, and public services could be impacted, leading to both immediate repair costs and long term economic impacts.'' ECan rivers manager David Aires said tens of thousands of cubic metres of gravel were removed from the Kowhai River to assist with reconstruction work following the earthquake. Local contractors and Environment Canterbury's river engineers have removed a further 25,000 cubic metres in the last eight years. ECan manages 18km of stopbanks along the Kowhai River, which are designed for a one-in-20-year flood event. This is equivalent to around 250 to 270 cumecs of water flowing at a rate of one cubic metre per second. Mr Aires said the Kaikōura flood protection scheme is being reviewed. ''Over the next six months we will be measuring riverbed levels so we can determine where further gravel extraction might be required in the Kowhai River as we work through the scheme review.'' Reducing flood risk in rivers has been a major focus for ECan and other regional and unitary councils, which led to the report ''Before the Deluge''. The report was presented to the Government in late 2022, warning of the risks and costs of a major storm or flood event. The Auckland floods and Cyclone Gabrielle, which struck in January 2023, are estimated to have resulted in between NZ$9 billion to $14.5 billion in damage. ECan set aside $25m a year over the next 10 years in last year's 2024/34 Long Term Plan and called on the Government to contribute $38m. Last year the Government announced $9.5m funding towards three projects, including upgrades to critical and aged flood management infrastructure across the region to make it more resilient to the changing climate. ECan also spent $22.6m in repair work following the May 2021 heavy rainfall event, which caused widespread flooding and prompted a region-wide state of emergency. LDR is local body journalism co-funded by RNZ and NZ On Air.
