Q&A: Why do we live in flood zones?

Flood damage in Edgecumbe, Bay of Plenty. Photo / Jamie Morton

A mere week after the tail end of Tropical Cyclone Debbie hit the North Island, another cyclone is bearing down on New Zealand. The MetService is warning Kiwis that Cyclone Cook could bring heavy rainfall especially to areas already saturated from last week. Professor Bruce Glavovic - EQC chair in Natural Hazards Planning, Massey University - answered a Q&A from the New Zealand Science Media Centre about the latest storms, flood risks and how to better prepare and plan for future events.

Why do some people live in flood zones?

New Zealand is a landscape of many physical perils - from earthquakes to landslides to floods.

The personal and community toll of these extreme events is terrible, but there are three main reasons people live in harm's way: legacy development, the property development process and our attraction to beautiful places.

Importantly, New Zealand communities face not only natural hazards, like earthquakes, but also face slow onset change due to climate and wider environmental change.

The latter can and will compound extreme events, like flooding, or the opposite, droughts - may be exacerbated in some parts of the country.

We facing rising sea levels, which is not a debate, but a reality.

Moreover, these environmental changes are superimposed on societal changes - demographically, economically and culturally.

Consequently, we need to learn to live and thrive in the face of complexity.

We need a robust community planning and decision-making system to enable communities to deal with this reality.

Our current statutory framework for planning has many strengths but it is not designed for the challenges of the 21st Century.

Would those houses in flood zones be there if they were built today?

Our planning system requires local authorities to identify natural hazards and to mitigate potential impacts, but not necessarily avoid the hazard.

There is no requirement to avoid putting people in harm's way; just that we mitigate the impacts.

The burden falls on local authorities - often without the capacity and resources to adopt proactive, strategic approaches to avoid exposure to harm or the wherewithal to reduce the risk facing communities already living in harm's way, due to legacy development.

It is unlikely that local authorities would allow new development to take place in areas subject to a one-in-50 year flood - a 2 per cent chance of a flood in any year - or a one-in-100 year flood, with a 1 per cent chance of a flood in any year.

But what if development was allowed in such places in the past - or on steep slopes prone to landslides and liquefaction ground?

Natural hazards are only one of many issues that need to be considered in deciding on new development.

We also have to consider factors like relationship to existing development and cost of connecting infrastructure and roading.

Natural hazard risk is not always a priority.

Despite scientific knowledge about flood and other natural hazard risk, there is in-built pressure to discount this risk and to approve development - because this is seen to meet needs in places under development pressure; and even areas not under pressure.

Do councils have a say over who lives in flood zones?

Local government in New Zealand does not dictate who lives where.

People who live in a flood zone, in general, have to cover the costs of protective works that they benefit from - through the rates they pay on their properties.

This question raises a deeper fundamental question about who creates natural hazard risk; who bears the consequences; and who shares responsibility for resolving this problem?

Does development make floods worse?

It can - by hardening the surface of the places we live, there is less chance for water to be absorbed naturally.

So, we need to look to ways to "design with nature" to take advantage of nature's ability to absorb floods.

Learn to live with water.

We design our infrastructure - like stormwater - to cope with anticipated flow volumes.

If we experience flash floods where the volume of water exceeds design standards, then we might compound the flooding say from a river.

Are you worried that the rush to build new houses and suburbs will make flood risk significantly worse?

Yes, the planning system can be used address the housing shortage in Auckland; but it needs to do so mindful of natural hazard risk.

But it is imperative to take a much wider view of the potential of planning to future-proof communities in New Zealand.

We have learned the cost of building in high-risk areas, like the red zone in Christchurch after the 2010-2011 earthquakes.

There is a compelling need to avoid putting people in harm's way.

Planning plays a pivotal role in this regard.

Whilst the housing problem in Auckland is clearly urgent and compelling, many other New Zealand cities and towns face static, and in some cases declining, demographic and economic circumstances.

This is a very different planning challenge from that facing Aucklanders.

But regardless of this issue, every New Zealander lives in the face of natural hazard risk.

Planning is more than delivering services and houses - it is key to building vibrant and resilient towns and cities.

We need to future-proof our communities, which is a much deeper challenge than simply building roads and houses and providing services cost-effectively.

We need constructive guidance and practical capability building support from Government so that local communities and their local authorities can provide consistent, well-informed and meaningful support and direction to so that our communities can weather storms, cope with sudden shock events and navigate inevitable change, turbulence, and surprise.

What does at risk of flooding mean?

Risk is the likelihood and impact of a flood or natural hazard.

In other words, flood risk is higher in the town of Whanganui than further upstream where there might be only a very small settlement - even though the likelihood is the same; because there are more people in harm's way.

This highlights an important insight.

Flood risk is the combination of the flood peril and a vulnerable population.

We need more focused attention on vulnerability - the societal conditions that make people susceptible to harm.

We can stop floods up to a point, like building stopbanks and protective seawalls.

But if we have a vulnerable population in harm's way, we face the prospect of a disaster.

However, we need to move beyond reliance on a "predict, protect and respond" mentality towards a more proactive planning approach that focuses on reducing vulnerability and building resilience and adaptive capacity in the face of complexity, uncertainty, change and contestation.

What do we need to look at for the future?

The lesson to be learned is simple - avoid putting people in harm's way.

But we face two very different imperatives and challenges.

First, when people are already living in harm's way, we need to make wise choices about how to manage natural hazard risk into the future.

Second, we need to be very cautious when we initiate new development in "greenfield" locations - because we are locking in risk in such places.

Do not discount natural hazard risk in such decisions.

Hence the need to be careful about willy nilly opening up new greenfield development around Auckland to meet housing needs.

Yes we have a massive planning challenge to address the housing, transport and related needs of people in Auckland. And we need a timely, cost-effective planning process to meet these pressing needs.

But simplifying planning procedures to deliver these essential services quickly can have perverse outcomes.

If we ignore natural hazard risk, the long-term costs to New Zealand will be massive.

Especially in the face of a changing climate and given the other changing dynamics facing our communities.

We need a planning system that enables communities to work together to understand and prepare for a complex, changing, uncertain and contentious future.

Our planning system needs to enable communities to have difficult conversations in safe spaces so that we become more resilient and sustainable.

The Government is looking at reforms to the Resource Management Act (RMA) to address natural hazard risk - and to possibly making wholesale changes to this law.

This may be absolutely necessary.

However, we need to look beyond RMA to how this law relates to other legislation and the way we make social choices in order to build a more robust system for public planning and decision-making; involving community members, mana whenua, government, the private sector and scientists, planners and built environment professionals.

This means that we need to consider legislative changes as a whole - not only the RMA - considering changes to the RMA in the light of provisions in the LGA, Building Act, CDEM Act, etc.

Only then will we build the statutory architecture necessary to enable our communities to build resilience and sustainability.

Moreover, legislative changes alone are not sufficient.

We need to enable effective implementation of statutory provisions.

The critical question is how to connect the formal and informal institutional arrangements that together shape community decision-making.

Most importantly, we need to open up, not close down the opportunity for community conversations about natural hazard risk and deeper concerns about resilience and sustainability.

For instance, what is the best future course of action for a community that has experienced repeat flood events in recent decades?

There are many such communities around New Zealand.

Many people living in at-risk location have deep spiritual, cultural and personal ties to the places they live.

But if there is a real prospect of loss of life and the things we hold dear, at what point do we need to consider relocation or managed retreat? How do we have such difficult conversations?

The elephant in the room is what our communities face in a changing climate.

With 95 per cent of the population living within 10km of the seashore - how are we going to deal with rising sea levels?

Sea level rise is a certainty - what is uncertain is quite how fast it is going to rise and what the locality specific impacts are going to be in the distant future.

But we cannot afford to postpone community discussions about what this means for us in New Zealand.

There is an urgent need for leadership - from Government, civil society, the private sector, science and the media to address this question: to open up the difficult conversations that are necessary to build resilience in the face of waves of adversity.

This is an issue of much deeper importance than the urgent problem of Auckland housing that dominates contemporary political debate.

We need to create safe spaces for communities to have difficult conversations about how to future proof our communities.

Only then will we be able to weather storms like those hitting the country now; and prepare for a future characterised by complexity, uncertainty, change and contestation.