14 Apr 2018

Droughts, floods to become more common in Southland

9:46 am on 14 April 2018

Southland will be at greater risk of drought and flood in the future because of climate change, a report by regional council Environment Southland warns.

Dry Southland pasture

Dry Southland pasture (file photo). Photo: Southland Regional Council

The report, Protecting our Communities, was released this morning and forms part of the council's long-term plan.

It projects infrastructure spending will increase to more than $7.5 million annually by 2048, from current spending of $4.1m.

The report said large portions of the region's stopbank network may face risk from liquefaction

Seismic activity from the Alpine Fault will also have a significant impact on Southland.

"The projected impacts of climate change mean an increased variability in emergencies over a shorter time - droughts to storms," the report said.

"This may increase the overall risk to the community and may test the ability of people to be well-prepared, and increase risks to economic productivity.

"A large number of Southland's population live on flood plains and despite the extensive flood mitigation work, flooding remains a significant risk.

"Rising sea levels provide a challenge for coastal communities. As this issue will affect several communities across local authority boundaries, the Southland Mayoral Forum will take responsibility to investigate the issues and response, and discuss with the community."

The data suggested temperatures in Southland would increase by 1°C by 2040 and 2°C by 2090, with more turbulent weather resulting.

"A warmer atmosphere can hold about 8 percent more moisture for every 1°C increase in temperature," the report said.

"Rainfall is projected to rise and heavy rainfall events are likely to become heavier and more frequent. Strong winds are also predicted to increase. Should these predictions play out, Southland would be exposed to an increased likelihood of natural hazards such as flooding and drought."

The predicted changes would also see a decrease in snowfall and a higher snowline which would have an impact on riverflows in the region and likely lead to larger winter floods.

"Environment Southland's general approach to infrastructure spending is currently conservative, largely due to predicted declines in population and ageing referred to in the demographic and economic issues sections of this strategy," the report said.

"This is despite the likely impacts of climate change making flood events more regular and more severe.

"Environment Southland will maintain the capacity to debt fund infrastructure improvements and repairs as required but is only planning to undertake a few major infrastructure investments in the period to 2048."

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