As Otago Regional Council staff look to incorporate natural solutions to flood risks across the region, Cr Gary Kelliher said because of the loss of productive land and "a lack of validation" that the new approach was necessary, the council’s ambition to expand native forests, "naturalise" rivers and construct wetlands to prevent flooding was an "utter joke".
"The comment’s been made that this should be included in our forward policy — 20% of productive land is on the table here for change," Cr Kelliher said.
"In a country that's desperate for maintaining its economic position currently and what it can do into the future, it really worries me around where this may be leading."
Boffa Miskell climate change specialist Sam Parsons presented findings of a Ministry for the Environment-funded feasibility study into nature-based solutions to address flooding in the Te Hakapupu-Pleasant River Catchment to the council’s science and resilience committee last week.
Mr Parsons said the catchment had been highly modified and at present wetlands covered only about 2% of their historical extent.
About half of the upper catchment was used for plantation pine forestry and, in the lower catchment, farming, infrastructure and housing were present, Mr Parsons said.
When plantation forestry was harvested there would be a "window of vulnerability" of up to eight years when the flood risk peaked significantly.
The nature-based solutions the consultancy investigated were most successful when they were applied "at scale", he said.
Under one of the scenarios examined, the Boffa Miskell team found areas of existing remnant native forests around key waterways and expanded those "pockets" of native forest into larger areas.
In another, the team looked at restoring waterways to their natural states.
"So taking these modified channels, opening them up, re-meandering them, planting out the riparian areas and fencing them."
A third approach was to restore and construct wetlands in the lower catchment area to increase flood storage capacity.
All of the approaches were technically feasible, he said.
But they would be costly.
"For these to be really feasible, not just technically viable, we need to have a bit more innovation as to how we make them economically viable because these aren't cheap solutions: they do cost money, they do change land-use at large scales," Mr Parsons said.
"So you can either look at retiring large areas of farmland around wetlands and creating them back into wetlands, or we can look at creating pockets of wetlands in a network."
At last week’s meeting, Cr Alexa Forbes said she understood Cr Kelliher’s concerns but said it was important to keep in mind nature-based solutions "work".
"Yes, it does take up some land, but its overall contribution to restoring the environment is superb," Cr Forbes said.
A staff report presented at the meeting said "where appropriate" staff would look to incorporate nature-based solutions into work plans "to support council alignment to its strategies as a priority solution".
The committee noted the report, only Cr Kelliher voting against.
