Food for thought: should we consider flood hazards as we build more homes?

As Auckland experienced once-in-a-century flooding, many people were asking: why was it so severe? Did it expose shortcomings in the city's infrastructure? As early as two weeks ago, two Auckland councillors called on the government and council to reconsider New Zealand's plans for urban intensification.

Housing developments in many New Zealand cities are becoming increasingly dense

 (Image credit: NZME; the same applies below)

 

Different views on urban intensification

 

Former Auckland mayor Christine Fletcher said: Auckland's floods have caused far too many tragedies, destroying homes and taking lives. We must stop those determined to build ever more homes in Auckland. The medium- and high-density housing rules have gone far beyond the provisions of the Auckland Unitary Plan, and the scheme is flawed.

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Auckland councillor Mike Lee said current central and local government urban development plans allowed three-storey homes to be built without resource consent or minimum green space requirements. This ideology was now facing a stark challenge from nature. He believed the new housing development legislation should be repealed so that decisions about intensification could receive the most careful consideration.

 

He said housing density should be increased in appropriate locations rather than everywhere, as the latter would only lead to more catastrophic consequences. Housing plans also needed to be supported by infrastructure, particularly stormwater drainage systems.

 

Meanwhile, Green Party land information spokesperson Eugenie Sage also recently said cities were building more homes to ease the housing crisis, but councils still needed to consider flooding. Sage said the government still had time to scale back its “Three Waters” reforms to “Two Waters”, leaving stormwater pipes under council responsibility.

 

She believed stormwater involved more than pipes for freshwater and wastewater: it also involved streams, floodways, ditches and parkland. These were best managed together by councils, which were better placed to plan for the complex land-use context stormwater required. Rather than focusing primarily on drinking water, councils should better understand how to provide flood storage areas and flow paths, and how these interact with streams and stormwater pipes. The lesson from Auckland's floods two weeks ago is that communities should be involved in planning a more sustainable city together.

Green Party land information spokesperson Eugenie Sage

 

Sage suggested that Auckland Council's flood review should focus on “how to manage stormwater” and “what changes when stormwater and wastewater systems are combined”, as this could cause sewage overflows along the coast.

 

 

She believed that, with Auckland's housing stock growing substantially, high-density developments needed sound natural drainage patterns and flood flow paths. We needed to understand how to make these systems more resilient.

 

Another issue that cannot be overlooked is insufficient green space. She pointed out that large property developments were bringing more asphalt and concrete, making the city's land “harder”. Better council development decisions were needed to establish drainage systems that allowed water to soak into the ground. The Green Party reportedly tried unsuccessfully to have urban vegetation coverage considered when National and Labour jointly proposed the Housing Supply Bill last year. Sage said that, although more trees and vegetation would not stop Auckland's floodwaters, they could manage rainfall, helping it soak into the ground and slowing flooding.

 

In October 2021, Housing Minister Megan Woods, left, jointly announced the new Housing Supply Bill with then National Party leader Judith Collins and National housing spokesperson Nicola Willis

 

ACT leader David Seymour also recently outlined his party's views on flooding. He said the new government elected at the next election must allow councils to reject plans for increased medium- and high-density housing in areas with vulnerable infrastructure, returning development in those areas to earlier urban planning settings. This would prevent conditions from worsening in areas with weaker infrastructure when natural disasters struck.

ACT leader David Seymour

 

ACT proposed making better use of funding for infrastructure and new urban developments. The new government should share half the GST on construction with local councils, giving them more funding to support urban development. Taking planning decisions away from those responsible for infrastructure was foolish. Building more homes faster for the next generation and keeping more young people in New Zealand were certainly important. But government funding for councils to repair infrastructure in areas of urgent need was clearly even more pressing.

 

Discussion and reflection

 

In this writer's view, orderly, purposeful land development makes cities more sustainable and liveable than haphazard urban growth. This does not advocate de-intensification. The Stonefield development is a good example: despite being a high-density residential development, it has an excellent stormwater drainage system.

 

Looking back to the early 20th century, Auckland's property development areas had extensive green space. Now the grass has disappeared, and more sewage and drainage pipes feed into the same “old” drainage system, exceeding its capacity and causing floods.

 

Over recent decades, both parties' urban planning decisions have often fallen short of expectations. In October 2021, they jointly rushed the Housing Supply Bill through Parliament, seemingly without fully considering the interests of ordinary people, builders, developers, councils and the natural environment. The new legislation appears to have been introduced not to build more affordable housing for the public, but merely to protect both parties' poor reputations on housing.