Where is Queensland going with flood management?

It is now more than two years since Queensland's disastrous summer of flooding, and there have been several bad floods since both west of the Great Dividing Range and near the coast. The time is right for asking what directions the state might be taking in terms of managing the problems caused by floods.

Soon after the floods of 2010-11 the federal government instituted a levy to raise funds for the recovery process, and later it allocated money for mitigation works at Ipswich and Roma. Now the state government wants to bring in another levy to raise a billion dollars for infrastructure protection over the next five years. Numerous mayors, several state ministers and the premier have made it clear that serious action must be taken to mitigate the effects of flooding. The time for flood mitigation, long lacking in Queensland, appears to have arrived.

But what do our politicians intend to do? Where is the state heading in its attempts to deal with the most costly agent of natural disaster that it has to cope with?

The many pronouncements made so far suggest that the approach taken will be a narrow one. Levees, new dams with flood storage capacities and the raising of major roads where they cross floodplains have been mentioned frequently, but it will be disappointing if the effort is limited to measures such as these. They have parts to play, but the best flood management is much more multi-faceted. It protects infrastructure and communities from floodwaters but it also seeks to limit the future growth of the problem itself. In addition it seeks to improve community responses to floods.

The most effective flood mitigation goes beyond merely controlling the water. It is also about living with the inevitability of flooding. There are many mitigation options.

Let's look first of all at the possibilities for flood control. Here we should reject grand schemes like cutting canals to allow water to be shifted from rivers in flood to rivers which are not: these would be hugely expensive and unlikely to be cost-effective. Building many small dams in the headwaters of rivers is also not likely to be worthwhile in cost-benefit terms and they will be environmentally very damaging. Likewise dredging river beds adds little to rivers' flood carrying capacity, because the channels are small and at most can carry only much smaller volumes of floodwater than the adjacent floodplains. In any case the floodplains must be drenched periodically in the interests of environmental health.

Then there are flood mitigation dams, which are expensive and have potential flood control impacts which are often overstated: remember Wivenhoe? Good sites are not always easy to find, such dams destroy wilderness or productive land and there will need to be a lot of them if they are to make substantial contributions.

Levees can be very effective, though it is rarely possible to build them high enough to keep out the biggest floods. But in association with diversion banks and floodway bypasses, if necessary with velocity control banks to reduce the erosive power of floodwaters, they can play a major part in protecting urban areas. Not all environments are suitable, though: where flood heights are great (for example upstream of major topographical 'chokes' on rivers) or where rivers break into several channels (as in deltas) levees are inappropriate.

Small dams called retention basins also have value in built-up areas, as does the lowering of ground levels to trap water and keep it out of streams until peak flows have passed. The lowering of sports fields and even residential yards in large numbers has been of considerable value in mitigating flooding in western Sydney.

All these options help prevent flooding or reduce its severity. They increase the separation of property and other assets from flooding.

Beyond the flood-modifying measures, altering the existing built environment by raising houses on site or by purchasing and removing buildings from locations where flood flows occur also offer significant possibilities. In 2006 Campbell Newman as Lord Mayor of Brisbane proposed a buyback of severely flood-prone properties along Brisbane's creeks, but there was no support from the ALP government of the day. Yet this measure, like house-raising, has frequently been utilised in NSW and elsewhere.

Other approaches have been given less prominence in recent discussions. Rarely have we heard about changing our approach to the use of floodplain land, for example by prohibiting the future building of residential premises (and indeed commercial ones) there. Yet doing this would actually strike at the core of the problem, which is the legacy of decades of inappropriate decisions mainly by local governments. Gradually, inexorably, we have increased our vulnerability to the flood threat to the point that it has become a huge problem. Sooner or later we must stop making the problem even worse.

Restricting further urban development on floodplains will be politically difficult, however. It will be strongly opposed by development interests which will complain about the 'sterilisation' of floodplains and indicate that building costs will rise if easily-developable sites are denied. But the true cost of housing in flood-prone areas must include the costs of flood recovery, which developers do not have to bear. They are borne by individuals and the public purse.

Not to make progress in this regard will be to admit that we are party to the wilful exacerbation of the problem of flooding. Worse, we will do this in an era when we know full well that further urban development on floodplains is guaranteed to increase community vulnerability. It will also guarantee the spending of large sums of money on relief and recovery measures and increase the demand for additional flood mitigation spending. Better, surely, to seek in future to avoid these things in the first place.

Not to reduce the further use of floodplains for urban expansion will involve a dreadful admission about how we govern land management. In effect it will say that our approach to urban development is economically eccentric. We will be committing ourselves knowingly to increasingly high costs to support those whose properties have been flooded and to replace items of infrastructure that have been damaged or destroyed. That we have persisted for decades with an economically irrational development mindset here must be recognised.

All this applies to redevelopment too. As the older parts of flood-liable towns and cities come up for redevelopment, an opportunity exists to wind back the problem bequeathed to us by past generations. We have two choices here: to re-build more effectively (for example by mandating higher floors and more flood-resistant building materials) or to require that only flood-compatible land uses are permitted.

What should definitely be avoided is the re-creation of what will in effect be whole new suburbs in redeveloped areas. Having large numbers of people living in high-set dwellings above floodwaters, potentially for days, would be ill-advised: the failure of normal power, water supply and sewerage services will render these areas uncomfortable during floods. And if fire should break out - not an uncommon occurrence during floods - such dwellings could become death traps. Superstorm Sandy six months ago in the eastern USA saw people die because fires in flooded areas could not be dealt with appropriately as a consequence of access difficulties.

Planning major new developments on floodplains, even if the floors of dwellings are elevated, is dangerous. People living in such housing are likely to consider themselves safe and often they will not see the need to evacuate as floods approach. Allowing such estates could be said to amount to a policy of 'deliberate entrapment' of the residents come flooding.

Whether we are talking about new development on the outskirts of towns and cities or redevelopment in their older areas, stopping the problem from getting ever larger and more costly would be one of the best flood mitigation measures we could take.

But the problem of the legacy of past decisions about land use will remain whatever we do about future development. Dealing effectively with the existing problem will require that flood warning systems are improved. Here the difficulty is not so much any lack of gauges to provide data from which to measure and model flood severity, or indeed the accuracy of flood predictions for communities in the path of coming floods. In the main these matters are well managed already.

The real problem is that too many people fail to understand the warnings they receive. Hence they tend to delay their responses (lifting items within houses or evacuating to safety) until they can see the floodwaters encroaching on them. All too often the results are that much of material and sentimental value that could be protected before inundation occurs is lost and that people evacuate through dangerous floodwaters when ideally they should have left earlier, before their escape routes were inundated. A crying need here is for better information on the likely flood consequences in an area to be attached to messages about forecast flood heights. This is rarely done well in Australia.

In addition, people need to be educated on the nature of the flood threat in their vicinity, how severe it might be in the rare very big floods, what they should do to prepare and what to do when they receive a warning of an approaching flood. An understanding of these matters will unlock the unrealised potential of flood warnings to limit damage and promote personal safety. There is good information in Queensland on the website of the Bureau of Meteorology and some councils have produced brochures on what people should do come flood time, but the educational effort so far has been both piecemeal and poorly co-ordinated.

Education about the nature of levees, including the fact that levee failure or overtopping can occur, is also needed. To date, people living behind levees have been allowed to believe that they are protected from all flooding. Sadly, every levee in Australia will be overtopped at some stage and some are likely to fail.

Truly effective flood mitigation will utilise a range of approaches, both structural and non-structural. All indications are that the Queensland government is convinced of the need to take the road of structural measures to reduce the severity of the flood problem, but there is little to suggest that it comprehends that more is necessary if genuinely high-quality mitigation are to be achieved.

The mix of measures must be carefully chosen to meet the circumstances of different areas. Flood warnings and flood education can be utilised in all flood-liable areas, and there are always some structural measures that will fit individual environments. But some devices will be locally inappropriate in terms of engineering or cost-benefit considerations.

What we need is carefully-considered proposals which make use of appropriate measures in each area. So far there is little sign that the state government is thinking broadly about the matter or bringing in the different sorts of expertise that should be applied. In talking largely about levees and dams they are consulting engineers, but the views of community safety and emergency management specialists with expertise in warning system development and community education are not being heard.

Queensland is about to make major decisions here. There is a danger, if the problem is not considered broadly and appropriate expertise is ignored, that we will not get mitigation that both works well and is cost-effective. That will mean a demand for further investment in mitigation measures to institute what should have been instituted in the first place.

Let's hope that the state government seeks flood mitigation which incorporates notions of both flood control and living more effectively with flooding. Let's hope too that it will try to stop the problem of the growth of community exposure to the hazards of flooding.

Surely we must recognise that we should seek to spare ourselves from repeated, wasteful and increasingly massive expenditure ─ not to mention personal heartbreak ─ on recovering from floods.