The Times Australia
Mirvac Harbourside
The Times World News

.

Creating ‘sponge cities’ to cope with more rainfall needn't cost billions – but NZ has to start now

  • Written by Timothy Welch, Senior Lecturer in Urban Planning, University of Auckland
Creating ‘sponge cities’ to cope with more rainfall needn't cost billions – but NZ has to start now

Tune into news from about any part of the planet, and there will likely be a headline about extreme weather. While these stories will be specific to the location, they all tend to include the amplifying effects of climate change.

This includes the wildfire devastation[1] on the island of Maui in Hawaii, where rising temperatures have dried vegetation and made the risk that much greater[2]. In Italy, summer temperatures hit an all-time high one week, followed by massive hail storms and flooding[3] the next.

Flooding in Slovenia[4] recently left three people dead and caused an estimated €500 million in damage. At the same time, rainfall in Beijing[5] has exceeded a 140-year record, causing wide-scale flooding and leaving 21 dead.

These northern hemisphere summer events mirror what happened last summer in Auckland, classified as a one-in-200-year event[6], and elsewhere in the North Island. So far this year, rainfall at Auckland Airport has surpassed all records dating back to 1964.

Given more rainfall is one of the likeliest symptoms of a changing climate, the new report from the Helen Clark Foundation and WSP[7]Sponge Cities: Can they help us survive more intense rainfall?[8] – is a timely (and sobering) reminder of the urgency of the challenge.

NIWA, CC BY-NC-ND[9][10] Pipe dreams The “sponge city[11]” concept is gaining traction as a way to mitigate extreme weather, save lives and even make cities more pleasant places to live. This is particularly important when existing urban stormwater infrastructure is often already ageing and inadequate. Auckland has even been cutting spending on critical stormwater repairs[12] for at least the past two years. Read more: Auckland floods: even stormwater reform won’t be enough – we need a ‘sponge city’ to avoid future disasters[13] Politically at least, this isn’t surprising. Stormwater infrastructure, as it is currently built and planned, is costly to develop and maintain. As the Helen Clark Foundation report makes clear, New Zealand’s pipes simply “were not designed for the huge volumes they will have to manage with rising seas and increasing extreme rainfall events”. The country’s current combined stormwater infrastructure involves a 17,000 kilometre pipe network – enough to span the length of the country ten times. The cost of upgrading the entire water system, which encompasses stormwater, could reach NZ$180 billion. This contrasts starkly with the $1.5 billion councils now spend annually on water pipes. The report makes clear that implementing sponge city principles won’t wholly solve flooding, but it can significantly reduce flood risks. Trees and green spaces The real bonus, though, lies in the potential for sponge city design to reduce dependence on expensive and high-maintenance infrastructure. There are already examples in Auckland’s Hobsonville Point and Northcote. Both communities have incorporated green infrastructure, such as floodable parks and planted wetlands, which kept nearby homes from flooding. But the report’s recommendations are at odds with some of the current political rhetoric around land use policy – in particular “greenfields” development that encourages urban sprawl[14]. Read more: National’s housing u-turn promotes urban sprawl – cities and ratepayers will pick up the bill[15] The report urges that cities be built upwards rather than outwards, and pushes back on residential infill development encouraged by the Medium Density Residential Standards[16]. Citing a recent report[17] on green space from the Parliamentary Commissioner for the Environment, the Helen Clark Foundation report argues for the preservation of urban green spaces – like backyards – as part of the flood mitigation approach. Preserving tree cover is another urgent priority. Trees help absorb rainfall, reduce erosion and provide essential shade and cooling in urban areas – counteracting the dangerous urban “heat island” effect[18]. Citing data from Global Forest Watch[19], the report states: Auckland has lost as much as 19% of its tree cover in the past 20 years, Dunedin a staggering 24%, Greater Wellington around 11% and Christchurch 13%. Read more: Planting more trees could reduce premature heat-related deaths in European cities by a third – new research[20] Incentives for homeowners Making Aotearoa New Zealand more resilient to extreme weather, the report says, need not break the bank. It recommends raising the national minimum standards governing the percentage of the total area of new developments that must be left unsealed. This would ensure the implementation of sponge city concepts, and see buildings clustered to maximise preserved green space. The government should also require local councils to plan for and provide public green spaces, and to develop long-term sponge city plans – just as they do for other types of critical infrastructure. Read more: We’re building harder, hotter cities: it’s vital we protect and grow urban green spaces – new report[21] Neighbourhoods could be retrofitted to include green roofs, permeable pavements and unsealed car parks. Land use and zoning could also encourage more vertical development, rather than sprawl or infill housing. The government could also provide incentives and education for homeowners to encourage minimising sealed surfaces, unblocking stormwater flow paths, and replacing lawns with native plants and rain gardens. More extreme weather and intense rainfall is a matter of when, not if. As the Helen Clark Foundation report makes clear, spending future billions is less of a priority than acting urgently now.

References

  1. ^ wildfire devastation (theconversation.com)
  2. ^ risk that much greater (www.theguardian.com)
  3. ^ massive hail storms and flooding (edition.cnn.com)
  4. ^ Slovenia (www.politico.eu)
  5. ^ Beijing (apnews.com)
  6. ^ one-in-200-year event (niwa.co.nz)
  7. ^ WSP (www.wsp.com)
  8. ^ Sponge Cities: Can they help us survive more intense rainfall? (helenclark.foundation)
  9. ^ NIWA (niwa.co.nz)
  10. ^ CC BY-NC-ND (creativecommons.org)
  11. ^ sponge city (theconversation.com)
  12. ^ cutting spending on critical stormwater repairs (www.nzherald.co.nz)
  13. ^ Auckland floods: even stormwater reform won’t be enough – we need a ‘sponge city’ to avoid future disasters (theconversation.com)
  14. ^ encourages urban sprawl (theconversation.com)
  15. ^ National’s housing u-turn promotes urban sprawl – cities and ratepayers will pick up the bill (theconversation.com)
  16. ^ Medium Density Residential Standards (environment.govt.nz)
  17. ^ recent report (theconversation.com)
  18. ^ urban “heat island” effect (theconversation.com)
  19. ^ Global Forest Watch (www.globalforestwatch.org)
  20. ^ Planting more trees could reduce premature heat-related deaths in European cities by a third – new research (theconversation.com)
  21. ^ We’re building harder, hotter cities: it’s vital we protect and grow urban green spaces – new report (theconversation.com)

Read more https://theconversation.com/creating-sponge-cities-to-cope-with-more-rainfall-neednt-cost-billions-but-nz-has-to-start-now-211181

Mirvac Harbourside

Times Magazine

YepAI Joins Victoria's AI Trade Mission to Singapore for Big Data & AI World Asia 2025

YepAI, a Melbourne-based leader in enterprise artificial intelligence solutions, announced today...

Building a Strong Online Presence with Katoomba Web Design

Katoomba web design is more than just creating a website that looks good—it’s about building an onli...

September Sunset Polo

International Polo Tour To Bridge Historic Sport, Life-Changing Philanthropy, and Breath-Taking Beau...

5 Ways Microsoft Fabric Simplifies Your Data Analytics Workflow

In today's data-driven world, businesses are constantly seeking ways to streamline their data anal...

7 Questions to Ask Before You Sign IT Support Companies in Sydney

Choosing an IT partner can feel like buying an insurance policy you hope you never need. The right c...

Choosing the Right Legal Aid Lawyer in Sutherland Shire: Key Considerations

Legal aid services play an essential role in ensuring access to justice for all. For people in t...

The Times Features

Macquarie Bank Democratises Agentic AI, Scaling Customer Innovation with Gemini Enterprise

Macquarie’s Banking and Financial Services group (Macquarie Bank), in collaboration with Google ...

Do kids really need vitamin supplements?

Walk down the health aisle of any supermarket and you’ll see shelves lined with brightly packa...

Why is it so shameful to have missing or damaged teeth?

When your teeth and gums are in good condition, you might not even notice their impact on your...

Australian travellers at risk of ATM fee rip-offs according to new data from Wise

Wise, the global technology company building the smartest way to spend and manage money internat...

Does ‘fasted’ cardio help you lose weight? Here’s the science

Every few years, the concept of fasted exercise training pops up all over social media. Faste...

How Music and Culture Are Shaping Family Road Trips in Australia

School holiday season is here, and Aussies aren’t just hitting the road - they’re following the musi...

The Role of Spinal Physiotherapy in Recovery and Long-Term Wellbeing

Back pain and spinal conditions are among the most common reasons people seek medical support, oft...

Italian Lamb Ragu Recipe: The Best Ragù di Agnello for Pasta

Ciao! It’s Friday night, and the weekend is calling for a little Italian magic. What’s better than t...

It’s OK to use paracetamol in pregnancy. Here’s what the science says about the link with autism

United States President Donald Trump has urged pregnant women[1] to avoid paracetamol except in ...