Flood management is not mostly about grand engineering schemes

These measures will cost a lot, and none of them is perfect or will 'solve' the problem of flooding by itself. Levees, for example, are not appropriate where floodwaters can be very deep (as when there is a 'choke' downstream which slows flood drainage) or in very flat areas (such as deltas) where rivers branch into several channels. Educating people about floods is not cheap, and it is often opposed and undermined by vested interests such as the real estate industry which believes ─ usually with precious little evidence ─ that it will reduce property values.

What is needed is a mix of measures tailored to the varying situations of different flood-liable areas. To work out which measures suit, the flood problem has to be studied and mapped, and measures chosen that fit the local circumstances and provide benefits that outweigh the costs of implementing them. Expert hydraulic and engineering analysis will be needed.

Experience around the world shows that levees often fit the bill, though they can be overtopped in big floods and it must be realised by those living behind them that they are not a complete solution. Flood warning systems also have a place, at least when people are educated to use them effectively. The creation of flood storage capacities in dams may have a role too, though not everywhere and usually to a smaller degree than people believe.

Queensland has had four successive summers of serious flooding in which some communities have been badly flooded more than once. There are signs that pressure is building to force the state government to take action. It needs to ensure that the action it takes is sensible, will reduce the flood problem without creating environmentally deleterious effects and will be cost-effective.

Here's a way forward. An agreement should be sought, involving all three levels of government, to invest in the management of flooding. It would seek to prevent the problem from being exacerbated by continued inappropriate development, and it would determine what means of flood mitigation would be appropriate in different locations. This would require councils and governments to examine the problem, community by community, and to devise cost-effective treatments. Community involvement would be necessary along the way.

Political courage and a strong investment of funds will be needed, over decades. Queensland could, if it chose to do so, spend a small number of billions of dollars over the next few decades.

If it spends wisely it will reap the benefits that many communities in NSW have won since, late in the 1950s and after a similar period of repeated, severe flooding, the three levels of government developed a partnership to invest in flood mitigation and better management of development on floodplains. For decades funding was committed on a 2:2:1 (federal:state:council) basis on measures to reduce the impacts of flooding. Much successful flood mitigation was achieved.

Grafton, in northern NSW, is an example of what can be done. Since the current levees were completed in 1970, no fewer than eleven floods have been kept out of the residential and commercial areas of the town. Since 2000 alone four big floods have been excluded, with damage saved amounting to perhaps $800 million. The levees, if they were built today, would cost in the order of $30 million, with a few hundred thousand dollars having to be spent on their upkeep each year. The ratio of benefits to costs there has been very high.

Grafton is but one case of effective flood mitigation in NSW. More than 40 other NSW towns have had levees constructed, and many retention basins have been built. Some dams were constructed with 'airspace' in which to store floodwaters. Houses in the most hazardous flood prone locations have been purchased, at market price, and then removed to allow clear passage to floodwaters. Many houses have been lifted bodily, and in some areas roads have been raised at low points to give them a measure of flood security. There has been investment in flood prediction services and in helping people to understand warnings and apply them to their own actions when floods threaten.

And for years NSW had regulations which at least placed a crimp on the tendency for councils to allow unwise development in flood-liable areas. The regulations have been weakened somewhat over the past decade in favour of simplifying development regimes, but that is a story for another day. Suffice to say that NSW will probably regret the recent loosening of its regulatory regime for new development and the reduction of investment in flood mitigation.

But much has been gained in NSW in terms of making flooding more manageable. What was done was not without environmental impact, but the impacts on nature were much less deleterious than would result from the adoption of the prescriptions Hamilton advocates.

We need to stop trying to control, dominate and overpower floods by means of grand engineering works. Making nature submit to our will is expensive and likely to fail. That is the way of decades past. We need to do more, though, to make it possible for communities to live more effectively and safely with flooding.