Head of Lake Wakatipu

Natural hazards adaptation project

The landscape at the head of Lake Wakatipu is made up of mountains, streams, floodplains and large rivers feeding into the lake. This magnificent natural setting makes the area an attractive place to live in or visit. However, it also means that this area is inherently exposed to natural hazard risks.

 

 

What are the natural hazards in this area?

This dynamic environment is regularly impacted by natural hazard events such as flooding and has a long history of large-scale environmental changes. These include migration of the braided Dart and Rees rivers across their floodplains, growth of the Dart and Rees deltas (landform created by sediment carried down the river to where it enters the lake), and common stream activity across the many alluvial fans.

As the Dart and Rees deltas continue to grow into the lake, the flood risk for the Glenorchy and Kinloch areas increases, and riverbed levels rise with ongoing sediment deposits. In addition, climate change is expected to bring more frequent and heavier rainfalls, increasing the flood hazard from the rivers and lake. The impact of these on people living in these areas is expected to get worse, particularly for low-lying lakefront areas and floodplains.

Other less frequent hazards such as earthquakes could also have a high impact on this area. This area is only 40-50 km from the Alpine Fault and other active faults. Earthquakes could trigger other events such as liquefaction, landslides and rockfall, or even a tsunami triggered by a large landslide into the lake.

 

 

Why is an adaptation strategy needed?

This area faces multiple natural hazard threats, with future climate and landscape changes increasing the potential consequences. We need to develop options to adapt to these risks, by understanding the risks and anticipated changes, and planning ahead for how to live with these hazards.

ORC has previously undertaken engineering works to address natural hazards issues such as flooding and river management. While engineering works provide temporary benefits, they do not fully deal with the problems permanently and are unlikely to be sustainable financially or environmentally in the long run.

A strategic and holistic approach is needed to address these issues in the longer term, which needs to also consider future climate change, landscape changes, and multiple and cascading natural hazards. It is very important that this strategic approach is developed collaboratively with the local community and other project stakeholders and partners, and that their values and views are incorporated into this planning.

 

What we want to achieve:

“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.”

 

We will consider the most frequent natural hazard events such as flooding, as well as the less frequent events such as major earthquakes, and how these hazard risks might change over time (100+ years).

The project area includes Glenorchy, Kinloch, and the surrounding rural areas of the Dart and Rees Valleys, Paradise, and Greenstone.

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.

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 are completing natural hazard risk assessments and providing technical 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.

 

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