Middlemarch susceptible to flash flooding — ORC

Snow Ave, Middlemarch, with the Tap & Dough Bistro at left, looked more like a river, during...
Middlemarch during recent flooding. PHOTO: file
The Middlemarch landscape is susceptible to flash flooding after high intensity heavy rain, the Otago Regional Council says.

The flooding at Middlemarch to start the year was not caused by the Taieri River overtopping, the council said.

It was due to heavy rain falling on short, steep tributaries of the Taieri River that flow from the Rock and Pillar range, it said.

Council natural hazards manager Jean-Luc Payan said the town was situated at the point a steep gully merged on to the flatter valley floor.

Flooding on these areas, known as alluvial fans, could lead to ‘‘debris flood events’’ when the tributaries carrying water to the river were overwhelmed, Mr Payan said.

‘‘These tributaries are prone to blockage and debris, which can cause the streams to break out of their existing channels at times of higher flow,’’ he said.

From the start of the year until the rain finally let up on January 3, more than 100mm fell on Middlemarch.

Snow Ave, near the centre of town, was under water on the Saturday and then, as the floodwater subsided, another bout of heavy rain inundated buildings a second time on Sunday.

It was the second major flood since November 2018 when one disrupted life in the town of about 200 people that lies within Dunedin city boundaries.

Otago Regional Council regulatory general manager Richard Saunders said the council completed its regular March Creek river management, vegetation maintenance and debris clearing work in November.

But there were no other flood protection works for the town, Mr Saunders said.

He said the council expected to be involved in coming discussions with the community and the Dunedin City Council about how to address the flooding.

In a recent media statement, the regional council noted that Middlemarch was not the only Otago town in this type of landscape.

Like Middlemarch, Roxburgh was near a steep, narrow catchment and alluvial fan.

Roxburgh has been hit in recent years by severe flooding, including a flash flood in November 2017 which caused major landslips and affected all three routes into the town.

hamish.maclean@odt.co.nz

 

Comments

Its amazing how after all these years ORC decide the flooding is because of an alluvial fan.
The message to ORC and DCC surely is to sort out March Creek drainage to ensure it runs our of the township easier.
Treat Middlemarch as part of Dunedin which is what it as and more regular maintenance to ensure local residents and businesses are not affected.
The area has affordable land and housing which will help grow the town in the future with Dunedin property becoming so expensive.

 

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