Ashburton River in flood. Photo: LDR
David Hill, Local Democracy Reporter
The government needs to invest in making Canterbury's rivers safer as climate change causes increased flooding, says Environment Canterbury chairperson Peter Scott.
A government report, Our Atmosphere and Climate 2023, released on Wednesday, showed time and money was needed to future-proof the region against more frequent and severe weather events, Scott said.
"Increased rainfall in Canterbury is putting pressure on our river systems and infrastructure, and damaging people's property's and livelihoods," he said.
"It shouldn't be solely up to ratepayers to fund the solutions that are needed. Co-investment with government is required to make a difference."
The report warned of bigger and heavier "atmospheric rivers", which carry water vapour from the tropics, often leading to huge deluges.
It also warned of warmer seas, coastal erosion, flooding in rivers, rising sea level, and impacts on biodiversity as the planet heats up.
Environment Canterbury chief scientist Tim Davie. Photo: supplied
Environment Canterbury chief scientist Tim Davie said there were "no surprises" in the report, but it highlighted issues the regional council had been grappling with.
"We are seeing it in Canterbury.
"We tend to think of sea level rise and flood risk, but there are other impacts which are not necessarily talked about, like acidification of the oceans and the loss of biodiversity," he said.
Increasing ocean acidification was caused by oceans absorbing carbon dioxide from the atmosphere, and impacted on shellfish and other fish species, Davie said.
Warmer seas were already affecting birds, such as Kaikōura tītī/ Hutton's shearwaters, which had to fly further in search of food, as fish moved to cooler waters, he said.
The 2021 Canterbury flood was an example of the effects of an "atmospheric river", he said.
A report by NIWA found the heavy rainfall that caused flooding in Ashburton in 2021 was 10 percent to 15 percent more intense due to the human influence on the climate system.
Climate change predictions for Canterbury indicate the region could expect more high rainfall, with much drier periods in between.
More severe droughts would increase the risk of wildfires, something Environment Canterbury was already anticipating this summer, Davie said.
Climate change was expected to exacerbate the effects of the El Nino weather pattern this summer.
Davie said by investing in infrastructure now, the impacts of climate change could be reduced.
Environment Canterbury was already funding more environmentally friendly public transport, by buying electric buses and making it easier for people to use buses.
The Canterbury Mayoral Forum is also working on a Canterbury Climate Partnership Plan, with Davie taking the lead.
"It is about pulling together and identifying what actions councils are taking and what we can do across Canterbury," he said.
Councils need to protect infrastructure, such as roads and drinking water, protect biodiversity, and tackle coastal erosion.
Environment Canterbury has identified the need to fund work on Canterbury's rivers that will help reduce the impact of future cyclones.
Options include increasing the size of stop banks, widening river margins to give rivers more room, and removing weeds, such as willows.
Davie said investing now would save money when a major storm hits.
"Smaller councils like those in North Canterbury will struggle to pay for this, but we need to look at the impact of these events, which goes beyond the local community, so it needs support from central government," he said.
- Local Democracy Reporting is Public Interest Journalism funded through NZ On Air