This post contains two guest posts from readers, both of which were sent to us after the flooding on Friday 27 January, both of which discuss how we handle our stormwater.
This is a guest post from Ed Clayton, who’s written for us before about Auckland’s relationship with freshwater, the potential for green-tracking light rail, and creating ‘green density’ with Ecological Build Zones.
I’m writing this two days after Tāmaki Makarau received more rain in one day than it usually does all summer. The Fire Service reported that every single vehicle was mobilised in response to the flooding. MetService has just issued another warning for rain over the next 24 hours and NIWA has predicted more moisture-laden tropical air making its way to us for the next 5 days. It’s just started raining again outside.
Flooding has been so widespread that it’s likely this will be the costliest natural disaster for Auckland. Climate change has exacerbated the floods, as warmer air can hold more moisture. I’m certain that insurance companies will be taking a long hard look at how extreme house prices will be influencing claims, along with a new affection for Auckland Council overland flow paths.
The flooding was so bad because Auckland has built over far too many of the small streams in the city. We’ve removed the ability of streams to cope with large volumes of water by building on floodplains and removing the hydraulic connectivity that is crucial for managing flood flows. Hard, impervious surfaces remove the ability for water to soak in, instead funnelling it straight into our stormwater system. And this carries with it the detritus of our urban spaces, resulting in pollution and closed beaches.
Wairau Valley is a perfect instance of this mistreatment, concrete-lined channels and pipes cannot cope with extreme deluges and so roads flooded, houses were swamped, cars swept away and tragically, people died.
However, where newer developments have been designed around more water-sensitive designs, flooding was minimal. A great example is how Hobsonville Point coped with the rain.
Whoever designed the stormwater system in Hobsonville Point can take a bow. Over 300mm of rain in 24h in a densely built area and last night there was only surface flooding on some roads. pic.twitter.com/1UkYAZbCiu
— Aaron Schiff (@aschiff) January 27, 2023
What can be learnt from this storm? A lot, if we want to, but as evidenced by Alec Tang, we haven’t learned much from the last one. It’s great that our new subdivisions get raingardens, swales and biofiltration devices, but for the already-built parts of our city, more is needed.
This post then, is a call for a new perspective on what water means for Aotearoa. We’ve just learnt the hard way that all infrastructure is water infrastructure, and this means we need to re-evaluate how and what we build. I’m advocating for all infrastructure to be assessed through a water-lens; how does this apartment building improve water quality in the local stream? How can we increase transport links and community connectivity while removing flood risk?
I’ve had thoughts about this for a long time, and I’m subscribing to ideas of ecological net-gain. This is also what Te Mana o Te Wai (in the National Policy Statement for Freshwater Management) sets out to achieve through recognising we have an obligation to improve freshwater for future generations. If we build something, it must improve water quality. No more offsetting or mitigation of effects. What this looks like in practice means that, over time, we gradually improve all of our infrastructure. This could be designing light rail to have green tracking, purposefully built to infiltrate and treat adjacent land use runoff. It could be creating ecological build zones that grant bonus development rights to buildings that incorporate green roofs.
It most definitely needs to be catchment-oriented planning that is a collaborative process with mana whenua. As we increase our urban housing density, we should increase our urban green spaces. Think pocket parks designed as stormwater detention, but that are social spaces when dry. Identifying where our overland flow paths are and buying properties to create linear wetland parks designed to flood and store water. Utilising concepts such as the Sponge City. Daylighting our buried creeks like Waihorotiu to create more spaces like Te Auaunga. Reducing and redesigning roads for private vehicles so that as we reduce our impervious cover, we also change the function of roads, encouraging them to become ecological links.
The ultimate goal of this should be to reintroduce quality green and blue spaces back into our neighbourhoods. We need to change our perception of stormwater away from one of nuisance, to one of resource. This is the 15-minute city, but reimagined as access to local swimming holes with great water quality, sources of mahinga kai, wetlands, native bush and streams that are biodiversity hotspots in our city. We know the mental wellbeing benefits of being close to nature, and by placing water outcomes first we can start to create a city that improves wellbeing, is climate resilient and equitable.
None of these changes will be easy, and I’m sure there will be many detractors (“Kiwis love their cars”). Much investment will be needed too, but as we find out more about the cost of this event in the coming weeks and months, can we afford not to?
This guest post is by reader Anna
Too much rain, not enough drains
First up, I am so so sorry, beyond what I can put into words, for those who have lost their lives, their livelihoods and their lifestyles over this awful Auckland Anniversary Weekend.
Yet I think that it makes perfect sense, because it matters, to ask: what could have been done to mitigate the awful impact this rain has had. Because the problem is not just too much rain. The stormwater drainage system in Auckland has failed to cope, and failed the poorest areas of our city worst.
While this rain is unlike anything Auckland has seen before, it wasn’t completely unexpected.
Auckland Council’s current (2021) Long Term Plan says:
We can’t continue to use the past to plan for the future – due to climate change, many of our natural hazard risks are not fixed (e.g. the frequency and intensity of storms in our region is expected to increase).
Those words were put on paper in 2021, but the science behind them has been settled for at least a decade. Auckland should expect more rain, and it follows that we should be looking after our drains.
Looking after infrastructure assets is a famously dull topic – in the words of John Oliver “If anything exciting happens, we got it wrong”. Did Auckland Council get it wrong?
One measure of whether infrastructure assets are being well managed, used by the Office of the Auditor General, is to compare renewals (which Auckland Council calls “replace existing assets”) with depreciation (the loss in value of the assets, from being one year older). While both numbers can vary up or down in a given year, in the long term the two numbers should average about the same. The OAG reported that nationally, across all assets, local council renewals in 2019/20 was 74% of depreciation and concludes that this “indicates that councils are not adequately reinvesting in their assets.”
So – has Auckland Council been adequately reinvesting in stormwater assets? Both depreciation and renewals for stormwater are published each year in the Annual Report. It’s a very dull job trawling through the fine print of ten Annual Reports to find these numbers, but who has anything better to do on such a rainy day? Here are the numbers.
Over the past ten years, Auckland Council’s spend on replacing existing stormwater assets has averaged 55% of depreciation.
The OAG report goes on to say:
If councils continue to underinvest in their assets, there is a heightened risk of asset failure and resultant reduction in service levels, which will negatively affect community well-being.
Many Aucklanders will have other words they could use, at this time, to make that point.