Q&A: Hazard and Visitor Risk Mitigation at Milford Sound Piopiotahi
September 22, 2021
September 22, 2021
Understanding the potential impacts of climate change and natural disasters on the visitor experience are key when planning to future-proof remote tourist destinations
In the third part of our ongoing Q&A series discussing the Milford Opportunities Project masterplan, we talk to Stantec’s Flood Risk Management specialist Andrew Craig about accounting for hazard and visitor risk mitigation for one of Aotearoa New Zealand’s most precious natural environments.
The steep topography is awe-inspiring but does mean avalanches and landslides are a critical risk. Sometimes these slips are triggered by small earthquakes or heavy rain and often occur without warning.
We gathered, interpreted, and cross-examined information from a variety of sources covering all natural hazards including flooding, sea-level rise, remote-source tsunami, and local landslide-induced tsunami.
The winding road into Milford Sound Piopiotahi is a challenging drive even for alert locals who are familiar with the conditions. You then add winter snow and ice, risk of avalanche or landslides, extremely high rainfall, driver fatigue, and distraction from the fantastic views.
We considered other elements of transport and business-as-usual risks such as ferries, cruise ships, recreational boats, aircraft, kayaks, walking tracks, water supplies, power and communications resilience, and evacuation options. Examining these elements enabled us to understand not only current risks, but future risks in the masterplan.
It could be argued that New Zealand’s beauty is partly due to its location on a tectonic plate boundary, creating stunning mountains but also landslides and earthquakes. When we are in the wilderness, we need to pay attention to what is happening around us. We must consider how we can enjoy the adventure and still get home safely afterwards. To use an analogy, wearing a crash helmet doesn’t need to stop us from riding the bike.
Milford Sound Piopiotahi is very close to the Alpine Fault. The latest estimates suggest a strong probability of this Fault producing a high magnitude earthquake over the next 50 years. This could trigger a large landslide capable of producing a sizeable destructive wave that significantly impacts everyone visiting the fiord at the time. While the masterplan cannot guarantee zero risks to everyone, we can make significant strides in assuring a higher chance of survival.
Each discipline ranked and shared the big-ticket items at early workshops to see how these lined up or clashed with other workstreams. We then reviewed long list and shortlist evaluations, providing additional information to inform site-specific decisions. This review included physical measures and changes to the way visitors access and move around (and within) the different sites.
We have a duty to look after our families and visitors to Aotearoa and invest in the environment now and for future generations, so the masterplan needed to look at least 50 years ahead. Therefore, any infrastructure design not only had to be robust enough for this challenging environment, but had to account for climate change and severe natural hazards.
Resilience, integrating safety with infrastructure, and overall experience informed our thinking throughout the programme. The integration of safety within our design will be a legacy we can all be proud of.
One of my recommendations was a more detailed assessment of the shape and speed of landslide-induced tsunami waves when they hit the water's edge, as this is heavily influenced by the shape of the shoreline in different locations. This assessment will help inform the design of the primary staff and visitor hub and other elements in the resilience strategy.
Sometimes we find ourselves trying to add up small items we think we can afford, and the sum of the parts looks too expensive or difficult to start. This project was a fantastic opportunity to step back and look at the bigger picture; where do we have the chance to bring about the most positive change, across multiple aspects at the same time? This requires more than making minor adjustments to ‘business as usual’ by looking at some rare impact events. Sometimes the solutions to manage those rare events allow us to make significant shifts in other areas too.
The masterplan allowed us to look at a wide range of risks with individual disciplines working to provide integrated solutions. This approach means risk management isn’t just a sticking plaster at the end to mitigate a gap in an existing design. Instead, it is woven into the fabric of the design, along with visitor experience, environment, culture, and governance, all brought together within our recommendations.