OTAGO REGIONAL COUNCIL - HEAD OF LAKE WAKATIPU UPDATE

Mar 8, 2022

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COMMUNITY UPDATE 16 | MARCH 2022
Kia ora koutou. We have a short update for you this month, as the Glenorchy liquefaction study nears completion and the Dart-Rees floodplain hazard mitigation approaches. As always, water flow data is available in near real-time on the ORC website. We will let you know when data from the new Rees River flow recorder is available, which will then be available online.

Glenorchy liquefaction study
A draft investigation report has been completed by the Tonkin + Taylor geotechnical consultant team, and this is now being peer reviewed by an independent consultant.
Once completed, we will share this information with you, and give opportunities to answer your questions on the investigation. This is expected to be by mid-year 2022.

 River flow monitoring station installed at Rees River near Invincible Creek confluence (December 2021).

 Dart-Rees floodplain hazard mitigation

A collaborative workshop session has been held to discuss possible strategies for mitigation of floodplain hazards at the Dart and Rees rivers and Glenorchy. This was held over one-and-a-half days last week and had input from 14 attendees.
Discussions were focused on approaches for river management options such as gravel extraction and river channel realignments, as well as engineering interventions like bunding and flood banking. This included review and discussion on all possible mitigation options that were suggested by the community during our drop-in sessions last year.

The two key questions for this project are:

• What river management approaches are viable and sustainable in the natural landscape around the Dart-Rees floodplain, and what are their potential outcomes?
• What does sustainable flood protection look like in the Glenorchy area, and what level of protection is realistically achievable?

Attendees were from the ORC Natural Hazards and Engineering teams, and QLDC Infrastructure and Roading teams, with three invited consultants providing specialist advice.

• Professor James Brasington (University of Canterbury) provided advice on river science and landscape change, based on his long research experience at the Dart and Rees braided rivers.
• Matthew Gardner (Land River Sea Consulting Ltd) provided information on the flood hazard characteristics. Matt is also undertaking the hydraulic modelling and flood hazard assessment project for ORC.
• Dr Grant Webby (Damwatch Engineering Ltd) is a highly experienced Engineer in hydraulic design, river engineering and flood management.  Grant will be compiling a summary report of all discussions and conclusions.                                                                                                                                                                                                                                                                                                                   

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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