HEAD OF LAKE WHAKATIPU
COMMUNITY UPDATE 23 | FEBRUARY 2023
Kia ora koutou
We were last in touch in December with a snapshot of the milestones in the Head of The Lake Natural Hazards Adaptation Strategy work programme.
There's more to come this year. Find out below what work we're undertaking in coming months.
The next formal update to the ORC councillors on this natural hazard work programme is planned for May 2023. This update will include reporting on all work completed since the last council update in June 2022, and updates on all work in progress, such as those projects noted below.
At about this same time, we will also update you on all findings and new information, and our plans for the next stages of the programme. As you'll see there is plenty on the go!
|
|
New assessments underway Following the Damwatch Engineering Ltd report released late last year (read more below), there is a similar assessment underway, this time focusing on possible hazard mitigation or management approaches for liquefaction and lateral spreading. It is also a high-level overview of potential management approaches which will help all of us consider the following questions:
- What mitigation is technically feasible for the liquefaction and lateral spreading hazards at Glenorchy township?
- What are the benefits of each approach?
- What are the indicative costs and key constraints?
We have also commissioned a flood hazard assessment study for the Buckler Burn (as pictured above), which is underway. We will share this information when complete, which we expect to be around May.
Together with the flood hazard study completed in 2022 for the Dart-Rees floodplain, this will complete the hazard assessments for the three main flooding sources which may impact Glenorchy; the Rees River, Lake Whakatipu, and the Buckler Burn. |
|
|
Update on Damwatch report
Last year, we shared the Damwatch report, which identified a range of potential hazard management interventions for The lower Rees River and Glenorchy township, The Dart floodplain and Kinloch access and The Rees floodplain and the Rees bridge. Find out more here.
Since then, we've been considering the findings of the report. Our first new project is to investigate improvements to the flood forecasting capability for the Rees river and Glenorchy. read more about that below.
With this work in mind, it would be great hear what you think of the report. We welcome your feedback by email headofthelake@orc.govt.nz or call us on 0800 474 082. Let us know if...
- This report has missed anything
- You have any questions, or if any information is unclear
- You agree with the expert assessments – if not, why not?
- You think any of the approaches discussed in the report should be investigated further – and why?
|
|
Check out the data
There are now approximately one to two years of monitoring data available from the three new environmental monitoring sites established by ORC in the Rees-Glenorchy area. The monitoring records from these three sites are shown below.
You can view this data in near real time here on our water monitoring pages. Click on Kawarau.
What's exciting about this data is that it can be used to help us review approaches for improved flood forecasting that could provide better, increased early-warning for potential flooding events in Glenorchy. The first step in this work will be analysis of the relationships between rainfall, river flows, and water levels in the Glenorchy Lagoon and Lake Whakatipu.
 |
|
How do the natural hazard risks compare?
And what's the difference?
Following the hazard assessments completed in 2022 for flooding and liquefaction hazards, ORC received requests from community members to help better understand the risk levels of these natural hazard events, and how these risks compare with other locations around New Zealand. We really appreciate hearing from you.
Over the years, we have commissioned and published a number of studies. The first hazards studies provided information of the characteristics of the natural hazard events - what are they. The study will now assess the risks of these. It will consider in more detail the potential impacts and vulnerability to those events - what happens when they occur.
It's not always easy to understand, and it helps to compare with other places. When ORC consultant experts start assessments in February 2023 (aiming to have it completed by mid-2023), we have also asked for a plain-language summary of all findings. Not only will these explain terms more clearly, but it will include comparisons of the natural hazard risks from other placed around Aotearoa/New Zealand, for example, a comparison of the liquefaction risk in Christchurch.
Let us know if you have any other ideas of what to include in this plain-language summary. |
|
Making adjustments
After the new lake level monitoring station was established by ORC at the Glenorchy marina, it was noted an there was an apparent level offset (about 100mm) of measured lake levels between this site and the levels measured at NIWA’s monitoring station within Frankton Arm.
We've re-surveyed the benchmark points for both of these monitoring stations and found a survey inaccuracy in a benchmark location. Lake Whakatipu water level records for Glenorchy marina have been adjusted and now show no significant difference in lake levels between measurement sites at Frankton and Glenorchy.
Our apologies if this has caused any confusion. And please note, the data graphs above are not affected by this. |
|
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. Click here to read more about the whole programme.
If you have questions or need information, visit our website to see the reports, get answers to questions and a handy summary of the June 2022 reports.
You can also contact the ORC Natural Hazards Manager, Jean-Luc Payan, on 0800 474 082 or email us for more information at headofthelake@orc.govt.nz. This email will go to our Natural Hazards team, and we will provide responses to any emailed questions, and facilitate answers from our consultants if needed.
 |
|
Head of Lake Whakatipu newsletter sign-up
If you are currently not receiving our monthly newsletters, you can sign up here and view archives of past editions.
|
|
Contacts
If you have any questions or would like to get in touch with us, please email us at headofthelake@orc.govt.nz.
|
|
|
|
