Managing flood risk

New Zealand | Thursday, 3 October 2024

Effectively managing flood risk requires a mix of immediate, practical actions and thoughtful long-term planning, explains WSP's James Reddish, Liam Foster, and Richard Woods.

With storms and extreme rainfall events projected to become more severe and frequent in many parts of Aotearoa New Zealand, both individual property owners and entire communities need to focus on how they can adapt to flooding now, while also preparing for future challenges.

Homeowners can take several practical steps to protect their properties from flooding. Installing flood gates, barriers, or raising houses are direct, albeit sometimes expensive, measures that can significantly reduce flood damage - provided they don't make flooding worse for others.

Water sensitive urban design can play a critical role. So can innovative building design solutions. While not focused on residential properties, Queenstown implemented flood-resilient designs for commercial premises such as movable storage racks and flood-resistant flooring, following the 1999 Lake Wakatipu flood.

Adaptations like these can allow quicker recovery from floods and highlight how even small, relatively cost-effective changes can sometimes make a big difference.

The need for long-term planning

While immediate property-level measures like these are important, a long-term vision for our catchments is more crucial for effective flood management. This could include measures outlined in our report with the Helen Clark Foundation on Sponge Cities and involves planning for future flood risks and making gradual changes over time at every opportunity.

Identifying high-risk flood areas at the catchment level and planning risk reduction solutions, including property buyouts, in stages, can help spread costs and avoid sudden disruptions.

Cities like Auckland and Christchurch offer valuable examples of this approach. They have developed, or are developing, plans to create green spaces and designated flood zones, integrating these strategies into broader urban development. Spurred by past disasters, their planning shows the importance of every region preparing for the long term and being ready for your event.

Balancing flood mitigation with buyouts

Deciding between investing in flood protection infrastructure and buying out properties is a complex and sometimes emotionally charged issue.

As climate change increases flood risk, maintaining and upgrading flood defences becomes more costly. Studies, including by Victoria University's Jonathan Boston, suggest that property buyouts can sometimes be a more cost-effective solution than extensive flood mitigation infrastructure projects.

However, it's important to recognise that these decisions affect more than just finances. The emotional and social impacts on people must be carefully considered. At the end of the day, managing flood risk effectively is as much about people as it is about property.

Managing property buyouts or relocations requires sensitivity to the personal and community challenges involved. Professionals working with homeowners, like those in Auckland, play a crucial role in navigating these issues compassionately.

Collaboration and community involvement

Successful flood management relies on collaboration between local authorities, insurance companies, and communities. By working together, stakeholders can develop solutions tailored to local needs and address broader flood risk management goals.

While decisions should blend practical, short-term actions that individual property owners can take with strategic, forward-thinking planning at the local and central government level, they should also consider the well-being of all residents, and not just be based on dollars and cents. That way, communities can better handle the challenges of flooding and climate change - protecting both people and property, ensuring a more resilient future for all.