Keeping communities safe but not in the usual ways

Contractor Alister Swann (left), and Environment Southland works supervisors Mitchell Harvey and Jimmy Turnbull inspect stop banks at Ferry Road near Invercargill.

In a place nicknamed the ‘mai mai’ sits a team of mostly blokes whose work once went largely unnoticed, but is now at the forefront of council operations and communities’ interests.

It’s thanks to the work of this team, Environment Southland’s catchment operations division, that over the years most Southlanders have been spared from flooding during times of high rainfall and rivers levels.

Events like Cyclone Gabrielle and planning for and managing climate change impacts have highlighted the importance of their mahi.

Many in the team have been around Southland’s waterways and the hallways of the regional council for many years – Paul Pollard, Dave Connor, Craig King, Clint Cartwright – their names will be familiar to many.

There’s some fresh faces too – Mitchell Harvey, Jimmy Turnbull, Stephanie Gray, Grant Gerrard, Jo Paterson and manager Randal Beal.

Together, they work on aspects of Southland’s natural resources and flood defences, through programmes that include gravel management, stop bank maintenance and land drainage management.

Protecting our infrastructure: Before and after photos of the tree removal work that was undertaken in River Street in Gore, to protect the integrity of the stop banks.

Climate change has brought with it an ever-increasing work programme for the catchment operations team and as we learn more about what is needed to protect our communities, best practice continues to evolve.

Recently, Clint, Paul and Randal travelled to Hawkes Bay to assist in the response to Cyclone Gabrielle, a first for the catchment operations team.

The biggest eye-opener was the sheer scale of the damage, and the look of devastation in the faces of the people affected.

There was also much to see and understand from a professional perspective.

“It was a real world experience of a worst case scenario,” says Paul.
“It was a good learning experience.”

Clint says he found the use of chevron plantings interesting. Chevron plantings is when you use large trees, like poplars, in flood ways. In some instances, it caught debris which prevented it from destroying infrastructure, and in other cases, it had caused water to over flow from stop banks, he said.

“They’re a bit of a double-edge sword.”

For Paul, the main takeaway was the fact that 40 years of river engineering work was so severely damaged, and in some cases destroyed, by one event.

“It shows we need to diversify how we manage our flood protection assets going forward, especially in the face of climate change.”

“We need to be looking at other options, not just building stop banks out and up, but in critical areas; things like moving stop banks back. It’s about thinking long-term and looking at the bigger picture.”

What that means for Environment Southland’s catchment operations team, is their load is growing and the work they have been doing will continue to diversify.

As Randal puts it, “it’s necessary work that is visible to the community and it’s work people will be seeing more of.” A recent example of this has been the removal of a series of high-risk trees from River and Richmond Streets in Gore.

Trees and shrubs on and near stop banks can interfere with the integrity, potentially leading to the banks failing.

The roots of trees and vegetation can weaken stop banks, and during a flooding event, water can begin flowing through this weak patch, often leading to a rapid failure.

Trees can also topple in heavy winds creating holes for water to flow through, and tree debris becomes a hazard during a flood, which can cause damage to infrastructure.

The tree removal in Gore was part of Environment Southland’s wider maintenance programme, which starts with annual stop bank inspections throughout the region, in winter each year. It includes educating and working with landowners to manage flood protection assets on private property, Randal says.

“The other aspect is identifying the maintenance work we need to carry out on our flood protection network.”

Looking to the future, there are more trees that need to be removed from our stop bank network. This includes many on the Otepuni and Waihōpai stop banks within the Waihōpai Invercargill boundary and in other communities, such as Ōtautau.

The catchment operations team is passionate about all of its work - to protect Murihiku Southland’s people and property.

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Keeping communities safe but not in the usual ways

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Keeping communities safe but not in the usual ways

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