View all the reports for the Head of the Lake Adaptation programme, as well as climate change reports and council updates.
If you have any questions about the reports and the adaptation project, please get in touch with us.
If you want to participate in the adaptation project:
ORC has completed studies aiming to help better understand potential approaches for adapting to or managing natural hazards including flooding, liquefaction and lateral spreading.
These reports do not give decisions or recommendations for a specific action but are information resources to help inform both the councils and the community as we together work to decide how to respond to these natural hazard challenges.
We welcome your feedback, please email headofthelake@orc.govt.nz
Please let us know;
- If you think the reports have missed anything?
- Do you have any questions, or is any information unclear?
- Do you agree with the expert assessments – if not, why not?
- Which of the approaches discussed in the report do you think should be investigated further – and why?
The geotechnical investigation, completed by Tonkin + Taylor Ltd (T+T), assessed the vulnerability of the township area to liquefaction and lateral spreading caused by a moderate to major earthquake, and the anticipated impacts of these hazards.
Independent experts peer-reviewed the report, read the full report:
Two investigations were delivered to the community in June 2022, and include a geotechnical investigation, by Tonkin + Taylor Ltd, looking at liquefaction and lateral spreading caused by a major earthquake. The second, by Land River Sea Consulting Ltd, assessed the flood hazard from the floodplain, Dart and Rees Rivers, and high levels in Lake Wakatipu.
These reports were first released to ORC and affected residents early in June. The wider public was notified afterwards.
The reports were endorsed by the Otago Regional Council on 9 June 2022.
Read the short summary of both report findings, explaining the key points with images to illustrate lateral spreading, the floodplain and what might happen in an earthquake or flood.
Liquefaction and lateral spreading hazard management assessment
A new assessment by Tonkin + Taylor Ltd, completed in February 2023, focusses on assessment of possible engineered hazard mitigation or management approaches for liquefaction and lateral spreading in Glenorchy township.
It identifies a range of engineering mitigation techniques for liquefaction and lateral spreading that could be considered for use on land, buildings and infrastructure. These techniques considered range from very robust options through to “do nothing” or smaller-scale interventions.
The report then shows how these techniques could be applied across the township, and provides a preliminary high-level assessment of how effective these mitigation works could be in reducing damage, and an indicative relative cost comparison.
The report by Damwatch Engineering Ltd focuses on management of three areas where floodplain hazards - flooding or erosion – may impact on the community or infrastructure in the head of Lake Wakatipu area;
- The lower Rees River and Glenorchy township
- The Dart floodplain and Kinloch access
- The Rees floodplain and the Rees bridge
November 2022
PDF | 10 MB
Flooding and erosion near the Dart and Rees Rivers are worsening, affecting Glenorchy, Kinloch, and nearby areas. Councils are using a planning approach to explore long-term solutions.
June 2022
PDF | 34 MB
Insights from Land River Sea Consulting's flood model for Rees and Dart Rivers. Assessing flood risks for Glenorchy and rural areas, including climate change impacts and stopbank vulnerabilities. Results spotlight flood risks for low-lying areas in Glenorchy, emphasizing the importance of preparedness measures.
The report identifies a range of potential hazard management interventions, and reviews the key benefits and constraints of those approaches.
These report does not give decisions or recommendations for a specific action. It is an information resource to help inform both the councils and the community as we together work to decide how to respond to these natural hazard challenges.
For each of the focus areas, the report includes tables discussing the engineering or river management interventions identified as possible approaches for management of floodplain hazards.
These assessments also included reviewing river management and engineered suggestions by community members as possible approaches for managing the flood hazard in the Rees River, Dart River and Glenorchy area.
They key report findings are presented as Tables 4.1, 5.1 and 6.1 of the Damwatch report. Each of these tables provides a summary of the potential intervention approach, and lists the key constraints which may be challenges in implementing that type of intervention.
Here is just one example.
| Intervention | Comments | Key Challenges for Inclusion in Adaptation Pathways Approach |
| River control structures or plantings (e.g. groynes to mitigate channel / stopbank erosion) |
Intervention only aims to bolster the security of the existing stopbank by mitigating the erosion hazard to it. OLDC has recently applied some rock armouring to the most vulnerable part of the existing stopbank. Short stub groynes constructed of rock material are an alternative form of bank protection to a rock revetment type of protection (they push high flow velocities away from the bank being protected). |
This intervention only provides increased erosion security to the existing stop bank, not enhanced protection from flood inundation. Other sections of the existing stop bank remain unprotected and vulnerable to attack by high flow volumes under flood conditions and as channel braids in the river shin over time. As with the existing stopbank, ongoing bed aggradation will eventually subsume groynes or other river control structures, thereby gradually reducing the level of service over time. Intervention does nothing to address the increasing flood hazard from the Rees River due to ongoing riverbed aggradation, flood breakout into the Glenorchy Lagoon and future climate change impacts. |
Example extract from Table 4.1 of the Damwatch report to show how assessment findings are laid out.
Land River Sea Consulting Ltd (LRS) assessed the flood hazard to the Dart-Rees floodplain and Glenorchy from the Dart and Rees Rivers, and high levels in Lake Wakatipu. Read the findings below.
This report was peer reviewed by independent experts, and review comments have been addressed in the finalised reports.
This report by Beca Ltd highlights risks to people and existing property to natural hazard events.
Three reports by Damwatch Engineering Ltd focus on how to manage three areas where floodplain hazards – flooding or erosion – may impact on the community or infrastructure in the head of Lake Wakatipu area
August 2024
PDF | 5 MB
August 2024
PDF | 8 MB
August 2024
PDF | 9 MB
A new report by Beca Ltd highlights the social and economic baseline of the community and explores how social and economic wellbeing could be impacted by natural hazard events.
An investigation by Land River Sea Consulting assessed the flood hazard of the Buckler Burn.
A report by Damwatch Engineering Ltd focuses on how to manage three areas where floodplain hazards – flooding or erosion – may impact on the community or infrastructure in the head of Lake Wakatipu area:
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The lower Rees River and Glenorchy township
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The Dart floodplain and Kinloch access
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The Rees floodplain and the Rees bridge
The report identifies potential hazard management interventions and reviews their key benefits and constraints.
Head of Lake Whakatipu Draft Natural Hazards Adaptation Strategy Community Presentation
This meeting was about The Draft Head of Lake Whakatipu Natural Hazards Adaptation Strategy.
This was an opportunity for locals to:
- Learn more about the Draft Strategy and its long-term vision and goals.
- Hear about existing and possible future responses to natural hazards.
- Explore the Action Plan.
- Understand how the Strategy will be implemented.
- Ask us your questions.
The meeting was held at 7pm on 13 February 2025 at Glenorchy Hall.
View the recorded webinar below and download the presentation notes below.
Glenorchy community presentation 10 September (Livestreamed)
7pm | Tuesday, 10 September | Glenorchy Hall
Join us to learn more about the findings of the Glenorchy and Kinloch risk analysis and the intervention study for the Rees and Dart floodplains – ask our team any questions.
Natural Hazards Adaptation Online Presentation May 2024
Presentation of report findings, May 2024
In an online meeting on 22 May 2024, ORC and consultants presented their findings of the work they carried out that investigated the socio-economic impact assessment for the Head of Lake Whakatipu area. The consultants shared their findings and answered questions from the public.
Presenters:
Intro to the project - Dr Jean-Luc Payan, Manager Natural Hazards
Socio-economic impact assessment – Jo Healy and Jerry Khoo, Beca Ltd
The meeting was recorded and is available on our YouTube channel or below:
Presentation of report findings, June 2022
In an online meeting on 2 June 2022, ORC and consultants presented their findings from investigations of the flooding and liquefaction hazards in Glenorchy township.
Presenters:
- Intro to the project – Dr Jean-Luc Payan, Manager Natural Hazards
- Liquefaction hazards – Dr Sjoerd van Ballegooy, Tonkin + Taylor Ltd
- Flood hazards – Matthew Gardner, Land River Sea Consulting Ltd
The meeting was recorded and is available below. You can read the reports here and see the presentation slides.
The meeting was recorded and is available below. You can read the reports here, and the presentation slides.
Professor James Brasington presentation Fluvial hazards at the top of the lake (April 2021)
- Watch video: Professor James Brasington presentation Fluvial hazards at the top of the lake (April 2021)
What is the purpose of this project?
The Head of Lake Wakatipu area – consequences of a changing future landscape and climate
Glenorchy – consequences of a changing future landscape and climate
ORC Presentation 1 for Glenorchy Community Association (October 2019)
ORC Presentation 2 for Glenorchy Community Association (July 2020) Glenorchy flooding
Glenorchy and Dart-Rees flood hazards - online presentation
Glenorchy Liquefaction hazards - online presentation
ORC Presentation Community update - liquefaction and flooding hazards investigations (June 2022)
ORC progressing flood resilience initiatives in Glenorchy
The Otago Regional Council (ORC) is working on a series of initiatives to improve flood resilience in Glenorchy, where parts of the township are vulnerable to inundation during high flow events.
Otago Natural Hazards Database
Our hazards database is intended to improve public access to hazard information and to help the public, local authorities, and others make informed decisions about their exposure to natural hazards.
Otago climate change risk assessment
Climate affects much of what we do in Otago, from horticulture in Central Otago to land drainage in Clutha delta. Climate change therefore does not function separately to the work that we do; it is a key consideration in all that we do. We want Otago's communities to be aware of climate change and will work with them to adapt to its effects on our region.
