Homes on flood plains?
‘When I first started the research, I assumed that the change in the probabilities for rainfall would happen decades later. [But] those probabilities are changing quicker than I or anyone predicted. We need to stop building in flood plains.’ BELINDA STOREY, ABOVE
into a new stormwater conveyance corridor – essentially a man-made stream servicing the entire housing area.
Instead of pipes, Roa and his team designed an open stormwater system, where water both drains along swales – wide, shallow grassy channels built into the street berms – and collects in recharge pits. The system avoids the stormwater outlet blockages that can cause backflooding into properties, and the permeable surface of the swales slows the water’s flow.
Residents spoken to by Sunday News say they were unaffected by the recent rainfall, with the system working precisely as it was meant to.
But despite the apparent success of that strategy, Roa believes it was the exception, not the rule. ‘‘Every other time, you really want to work with your natural topography and natural features as much as possible.
‘‘As a first port of call, those [flood risk] areas should be avoided at all costs.’’
Climate change minister James Shaw has a one-word answer when asked if development should still be going ahead in flood zones: ‘‘No.’’
So if everyone – from stormwater engineers to climate change researchers to politicians to community advocates – is so unequivocal, why does it keep happening?
‘‘There’s probably a number of reasons, one of which is that there’s no national direction to councils not to authorise construction on flood plains,’’ Shaw says. ‘‘And because there’s a housing crisis, councils are feeling the pressure to expand housing stock, and I think some of them will have just been making those tradeoffs.’’
Many councils are also ‘‘fairly poorly resourced’’.
‘‘I suspect that a lot of council planning capability was built in a world where we didn’t have the effects of climate change being felt as markedly as we are now.’’
Work on reforming the law is under way. The Natural and Built Environments Bill, which will be the main replacement for the Resource Management Act, is at select committee stage, along with the Spatial Planning Bill, which will require long-term regional spatial strategies.
‘‘They’ll probably be quite directive to councils about where not to build in future,’’ Shaw says.
But he points out they won’t solve the problem of what to do about houses that already exist in flood zones. The issue of ‘‘managed retreat’’ – the deliberate removal or relocation of at-risk dwellings and communities – is what the third act of the trilogy of reforms deals with: the Climate Change Adaptation Act.
That bill hasn’t even gone to Cabinet yet and Shaw doesn’t put a date on it. ‘‘It’s an incredibly complex piece of work. I’m more interested in getting it right than I am in rushing it.’’
Even once the reforms are passed, though, the actual implementation will take years, he says.
‘‘So there’ll still be a gap during which time you could see some development that’s inappropriate. So we are considering the possibility of interim direction as well.’’
That interim direction is something Auckland councillor Richard Hills would love to see.
Hills chaired a council planning, environment and parks committee meeting on Thursday that agreed to go ahead with a review of all the council’s planning rules and tools. The council would also seek an urgent meeting with government ministers about whether special emergency powers were possible in the aftermath of the flooding.
Several councillors asked at the meeting whether it was possible to revoke recent consents that had been granted for building in flood plains. Hills told the Star-Times he didn’t think that was legally possible, but emergency powers might allow the council to pause current applications that have been lodged.
The council is often hampered by the current law when considering applications for building in hazard zones, Hills says. ‘‘As long as you can prove you can do it, generally you have to permit it. So it’s whether you could do a plan-change to prohibit, is the question we need help with from the government.’’
He, too, wonders whether a one-ina-100-year risk, measured and modelled at a point in time, is still fit for purpose. ‘‘That measure, just by looking out the window, feels like it’s not an accurate way to describe these events any more.’’
After weeks of rain, the sun is finally out in Ventura St and Diane Tieni and her neighbours have laid salvaged possessions outside to dry.
There is no structural damage to the house, so for now, she and her family are staying put. ‘‘I’d love to move, but where am I going to move to with the housing crisis?’’
Around the corner on Bede Pl, mounds of mattresses, wrecked furniture, ruined carpet, and other belongings beyond saving, teeter on berms outside yellowstickered houses.
Next door, silhouetted against a bright blue sky, builders clamber along the wooden framework of more townhouses under construction. A Kā inga Ora branded hoarding is attached to the fence: ‘‘New warm, dry homes are coming, Mā ngere.’’