About the programme
The Head of Lake Wakatipu Natural hazards adaptation programme
The objective of this work programme is to
"provide a framework to actively manage risks associated with natural hazards for the resilience of the area located at the Head of Lake Wakatipu, including Glenorchy and Kinloch.”
This hazards adaptation programme was initiated because this area faces a complex mix of natural hazards, some of which are expected to increase in likelihood and severity.
This setting requires a comprehensive approach to developing a hazard management response, which takes a long-term view and encompasses all types of natural hazards. Reactive or very localised responses are likely to have only shorter-term benefits, so the most effective way to deal with this type of complex setting is to take a long-term adaptation view, and working with the community to develop resilience.
This is the same approach ORC are taking to other areas facing complex natural hazards challenges within the Otago region – such as in the South Dunedin, Taieri Plains and the Clutha Delta areas.
The work programme is considering all types of natural hazards and their possible impacts in the head of the lake area – this includes floodplain hazards and alluvial fan such as flooding and erosion, but also seismic and geological hazards.
Some of these hazard types are expected to change through time, and their likelihood or impacts may increase in future due to these landscape or climate changes. These factors are expected to cause increases in the future flooding hazards for the Dart and Rees floodplains area, for example:;
- Climate change projections developed by NIWA show significant increases in both rainfall and river flow variables for the Dart and Rees catchments.
NIWA 2019 report
- Landscape change assessments by the University of Canterbury have shown how riverbed sedimentation may affect flooding hazards on the Dart-Rees floodplain.
Fluvial hazards at the top of the lake - Presentation, Professor James Brasington.
- Land River Sea Consulting have completed hydraulic modelling and flood hazard assessments.
- Damwatch Engineering have provided river management and engineering expertise.
More details on this work programme are included in ORC update reports to council in May 2021 and June 2022.
Who's on the team
The project to develop the strategy is being led by the Otago Regional Council, in partnership with Queenstown Lakes District Council, Department of Conservation, Aukaha and Te Ao Marama, working together with the local community.
From Otago Regional Council are Jean-Luc Payan ORC Natural Hazards Manager and Tim van Woerden, Natural Hazards Analyst.
In addition, we have several consultants providing specialist inputs and advice for the project. These are:
- Dr Paula Blackett from NIWA is providing expertise in implementing the adaptation pathways approach to natural hazards and risks.
- Professor James Brasington from University of Canterbury is providing technical expertise in river morphology and floodplain hazards.
- The Tonkin + Taylor hazards team have completed natural hazard assessments and providing geotechnical advice.
- Aukaha and Te Ao Marama are representing local iwi, Ngāi Tahu, and will provide cultural direction and understanding to ensure an appropriate cultural values statement is developed for the strategy.
The work programme direction
This programme is following the Dynamic Adaptive Pathways Planning (also referred to as DAPP, or ‘Adaptation Pathways’). This the approach we are using to develop a longer-term natural hazards adaptation strategy for the area at the head of Lake Wakatipu.
This ‘Adaptation Pathways’ approach has been developed by the Ministry for the Environment as a blueprint for community-led decision making in areas affected by natural events and climate change.
MfE Coastal hazards and climate change: Guidance for local government
This is a hazard management approach developed specifically to help plan and adapt for situations where the future is uncertain – it allows for flexible and adaptive decision-making, and for planning even when there may be uncertainty about the timing or impacts of future changes.
It’s an approach that helps develop long-term responses to natural hazards affected by environmental changes – such as flooding or coastal hazards affected by climate changes. Other types or natural hazard, such as geological or seismic events like landsliding or liquefaction will also be considered within this approach as part of the wider multi-hazard context.
This adaptation approach is often shown as a 10-step decision cycle (as below), and can be simplified as the sequence of five steps shown in the figure below that.
10-step decision cycle, Coastal Hazards and Climate Change (MfE).
Simplified five step sequence
Work completed so far
The programme work to date has been focused on developing the understanding of the natural hazards and natural processes in the head of Lake Wakatipu area.
These studies include:
- Analysis of floodplain changes and river science (University of Canterbury, James Brasington)
- Development of projected climate changes for the Otago region (NIWA)
- A hazards review and preliminary risk assessment for the head of Lake Wakatipu area (Tonkin + Taylor Ltd)
- Flood hazard modelling for the Dart and Rees Rivers and Glenorchy (Land River Sea Consulting Ltd)
- Geotechnical assessments of the stability of the Rees-Glenorchy floodbank (WSP and Tonkin + Taylor Ltd)
- Analysis of the liquefaction and lateral spreading susceptibility at Glenorchy (Tonkin + Taylor Ltd)
- Assessments of the alluvial fan hazards at the Buckler Burn (GeoSolve Ltd and Massey University)
- Hazard assessment following the April 2022 debris flow on the Queenstown-Glenorchy Road (WSP)
These hazards studies provide a much more detailed understanding of the natural hazards in this area, and will help to inform a community discussion on hazards response. Throughout this period, we have also been in touch with the community.
Keeping the community updated.
Natural hazards reports, findings and community presentations
2022 flood hazard findings and liquefaction hazard assessments
There will be additional natural hazards studies required for this work programme, such as a study to carry out revised assessments of the Buckler Burn flooding hazard, which is currently being scoped.
Any new findings will be shared when available.
How this work fits with ORC’s other natural hazards work programmes
The specific mix of natural hazards and physical processes in the head of Lake Wakatipu is unique to this area, but many other locations in Otago are exposed to the potential impacts of other combinations of natural hazards events.
ORC works to understand these hazards through hazards investigations, and has a responsibility to manage hazard impacts through development of adaptation or hazard management work programmes.
This type of natural hazards adaptation and hazard management programme is a usual part of the ORC natural hazards work activities. ORC has previously completed, or has programmes underway or planned, to develop natural hazards management strategies for many locations within Otago, including;
Map of the Otago region showing the locations where ORC has developed natural hazards management strategies, or where these are in progress or planned.
