David Jenkins is CEO of the Institute of Public Works Engineering Australasia. IPWEA is a Sponsor of the Herald’s Infrastructure report.
OPINION
Using natural “green” assets in traditional hard “grey” infrastructure projects is gaining momentum worldwide, and New Zealand is naturally well-placed to lead the way.
It can also have lower capital outlay and health benefits compared with a hard-engineered solution.
Natural assets can not only be cost-effective, but unlike engineered assets, they can provide a range of ecosystem services, increase in value rather than depreciate, and self-replace rather than costly renewal – although, like any asset, they need to be effectively maintained.
It has also been proven that using natural vegetation can lower air temperatures and reduce urban heat island effects.
New Zealand initiatives
New Zealand is already moving in this direction.
In September, Tāmaki Makaurau Auckland will host the World Green Infrastructure Congress, where more than 500 delegates will share their ideas on this growing movement.
The three-yearly update on the state of land in Aotearoa New Zealand, released in April by the Ministry for the Environment and Stats NZ, noted how ecosystems – such as soil, indigenous forests, wetlands, and dunes – are “foundational natural infrastructure” that underpin the nation’s economy, help protect against disaster and support public health.
The report says natural infrastructure supports the food sector, reduces soil erosion, and protects coastal areas against storm surges and sea level rise.
“We appreciate the benefits built infrastructure provides, but many of us don’t think of, or value, natural ecosystems and landscapes in the same way,” said the ministry’s deputy secretary – strategy, stewardship and performance, Natasha Lewis.
Some local case studies are paving the way. In Auckland, the Botanic Gardens have included native plants on the roof of the toilets, absorbing and treating rainwater.
Auckland Botanic Gardens. Photo / Doug Sherring
The “living roof” is combined with a vegetated swale – designed to manage water runoff – which slows down and filters the water flow and delivers cleaner water back to the lakes in the gardens.
As communities face the challenges of tomorrow, we can seek to learn from Te Ao Māori, the indigenous worldview of the Māori people in Aotearoa, New Zealand. By seeking a broader understanding of holistic and sustainable approaches to environmental protection, we can foster a deeper connection with the natural world and a greater sense of community empowerment.
In response to flooding issues in the Mt Roskill and Mt Albert areas, the Auckland Council replaced the existing concrete stormwater channel with a wider natural stream channel. Using vegetation as part of the channel increased the water-carrying capacity, allowing more water to soak naturally into the ground.
The valuation challenge
The natural asset approach poses challenges and complexities when reporting natural assets on the financial balance sheet. While efforts are being made to quantify the financial costs and benefits and assign them a value, the International Financial Reporting Standards do not provide specific standards solely for natural assets. This can lead to natural asset solutions being overlooked, but work is being done to find a usable valuation method.
Canadian not-for-profit organisation the Natural Assets Initiative (NAI) examined the response to flooding by the City of Grand Forks in North Dakota, United States. It found the nearby Kettle River floodplain reduced flood damage to urban buildings during high-flow events by between CAD$500 and CAD$3500 per hectare.
By understanding the value and benefits, the city can confidently invest $51.6 million in floodplain management, which includes buying back properties and restoring them for the community’s safety and well-being.
Change in thinking
Increasingly, the smart city toolkit includes the natural asset infrastructure approach, recognising nature is perhaps the smartest infrastructure solution available.
It is, by definition, resilient and sustainable and can deliver many of the resources smart cities need to achieve their goals.
Biodiversity is increasingly being factored into the criteria for smart cities, and what could be better than promoting and maintaining biodiversity than natural habitats, which also provide amenities such as parks?
Infrastructure and town planners have traditionally been too quick to turn floodplains into housing developments, and carparks and creeks into stormwater drains. All too often, wetlands have been drained and houses and commercial property have been built on the site. This has been considered good policy because these developments deliver revenue from taxes and rates.
Using natural assets as part of a holistic, long-term infrastructure solution comes from a change in thinking that says asset management is fundamentally about service delivery and effectively, reliably, and sustainably delivering services.
It looks beyond the traditional view of natural assets as being purely recreational or social amenities and that they have to have some subjective beauty if they are to be integrated into urban plans.
Floodplains and wetlands may not always be the most attractive natural environments, but they have a role in nature, which they also play in our cities and towns. If we want our cities to be smart, sustainable, and resilient, we should consider using them as an effective alternative to grey or hard-engineered solutions.
