HEAD OF LAKE WHAKATIPU

COMMUNITY UPDATE 42 | NOVEMBER 2024

Kia ora koutou,

In this month’s edition we share links to the Safety and Resilience committee meeting, which is happening from 1pm‒5pm this afternoon. This meeting includes an update about the programme and our next steps.

Soon after the heavy rain event in October, a team from ORC flew over the Rees and Dart rivers to check the flood flow levels using a technique called heli-gauging. If you’d like to learn more about heli-gauging, check out the images and story below.

ORC Safety and Resilience Committee meeting

On Thursday, 7 November, from 1pm, we will be presenting an update about the Head of Lake Whakatipu Natural Hazards Adaptation Strategy work programme to the ORC Safety and Resilience Committee.

What’s coming up next?

Planning is underway for community engagement between December and February 2025 to share the draft adaptation strategy and seek your feedback and input. We will have full details in our December edition.

How can I find the report and view the meeting?

You will be able to access this committee report via the committee meeting agenda here. You can also follow the discussion of the report at the ORC Safety and Resilience Committee meeting from 1pm today, here.

Image: The Dart River bridge before heavy rain on 23 October 2024

Image: The Dart River bridge after heavy rain on 24 October 2024

Go with the flow: how we measure flood events

On 28 October, we carried out heli-gauging work on the Dart and Rees rivers.

What’s heli-gauging?

It’s using a helicopter to tow a purpose-built kayak across a river with an acoustic water depth and water velocity measuring device.

Heli-gauging is one of the tools we use to ensure our flood network is calibrated and reading correctly. It gives us important accurate flow data so we can:

• Communicate the impacts of a flood event and warn communities on how to respond

• Ensure our schemes are performing as they should

• Improve our flood models and predictions

• Enable future upgrades or redesign of flood networks efficiently.

Image: Heli-gauging the Dart River at a measured flow of 837 cubic metres per second

Why do we use this heli-gauging method?

It is the most accurate and one of the safest ways to calibrate our flood network in high-flow flood events in big rivers. It can also help us to get where we need to be when road flooding makes access impossible.

We’d like to thank the Heliworks team in Queenstown for providing the highly skilled pilot that made heli-gauging possible over the Dart and Rees rivers.

The flows recorded on the day were:

• 150 cubic metres per second on the Rees River

• 837 cubic metres per second on the Dart River

Image: Heli-gauging the Rees River at a measured flow of 150 cubic metres per second

Image: Specialist software showing the flow velocity and depth data in real time

As always, we value your feedback

This adaptation programme was initiated because complex, increasing natural hazards in the Head of Lake Whakatipu require a comprehensive management response that takes a long-term view and encompasses all types of natural hazards.

This is your community, and we want to work with you to develop understanding and resilience.

If you have questions or need information:

• Visit our website to learn more about the whole programme.

• Read the reports

• Watch the presentations

• Get answers.

   

You can also speak to a member of the ORC Natural Hazards team on 0800 474 082 or email us for more information at headofthelake@orc.govt.nz.

We will provide responses to any emailed questions and facilitate answers from our consultants if needed.

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Contacts

If you have any questions or would like to get in touch with us, please email us at headofthelake@orc.govt.nz.