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Only twice in the 50 years since construction of the lake began has there been mild flooding in Canberra over the level of the lake - at the Causeway. Both floods were before completion of the Googong Dam; some like to believe that any flood in old Canberra is now almost impossible because of that dam. Perhaps, but only if we are prepared, by a quick emptying of the lake, to drown the lower Molonglo Valley, and the citizens of the newer suburbs we are planning there.

That there was a good contour map of the ACT available to the Griffins in Chicago 100 years ago makes surprising the lack of maps in south-east Queensland, where an urgent priority for flood planning is just such a map, or its modern interactive computer equivalent.

The final report of Queensland's floods inquiry says that Brisbane City Council, Ipswich City Council, Somerset Regional Council and the Queensland Government should ensure that ''as soon as possible, a flood study of the Brisbane River catchment be conducted. It should collate historical rainfall data, as well as design data and radar, stream flow data, tide levels, inundation levels and extents, data on the operation of the Wivenhoe and Somerset dams, river channel and floodplain characteristics including topography, bathymetry, development and survey data''.

The data should go into a hydrological model so that planners can work out what happens with different amounts and intensities of rain, or rain in different places, soil saturation, the initial water levels of dams, the effects of different rates of release of water from dams, the effects of tides on the whole shebang, and the consequence of closely occurring ''rainfall events'' as rainfall is now described by resilient disaster types.

The inquiry recommends that these models be tested to be sure they work in practice as well as in theory. We want them to predict changing volumes and rates of flow of water (or ''hydrograph attenuation''); probability statistics for flood volumes and peak flows, and the timing of major tributary flows. The model should be able to predict flood heights, extents of inundation, water speeds, and rates of rise and durations of inundation for floods of different probabilities, cope with movements of sediment and changes in river beds during floods, and be able to predict the ''backwater effect'' if both the Brisbane and Bremer rivers (or any other two rivers) are flooding at different rates.

Two closely printed further pages of ''summary'' recommendations from the inquiry further detail the types of maps, models and data which should be collected. Every urban area of Queensland should have a recent flood study for use in floodplain management, it says in tones which suggest that this would be new. Councils, it says, should maintain up-to-date information about floods, and should develop maps showing ''zones of risk'' (at least three) from known information about risks of flooding, and should make them available to the public.

These are far from the most newsworthy recommendations of the flood inquiry but that they should need to be said speaks volumes about Australian disaster management.

Brisbane has long had regular floods - the last one, in 1974, inundated much the same area as the 2010 one, and caused much the same damage, if not, mercifully, such a loss of life. After 1974, as after the flood disaster before that, and the disaster before that, civic fathers swore that we would ''learn'' from the flood and not build in obvious flood plains again. Within a few years, greedy politicians, developers and citizens again forgot all of the lessons of last time and began encroaching into high-risk areas. In due course, Commonwealth taxpayers, moved with pity for plucky and independent idiots, underwrite, yet again, much of the cost of their wanton stupidity. And the more wicked and wilful cupidity of politicians, bureaucrats and the development industry.

There is, each time, something or other in the nature of excuse. Some Queenslanders, for example, had convinced themselves that building the Wivenhoe Dam meant that floods could no longer happen. Hardly, particularly if, as occurred this time, the dam is full because of much rain in a short time.

Soon, thanks to the way the inquiry has been reported, many Brisbanites will believe that flooding was the result of a misjudgment about water releases from the dam. The engineers in charge left it too late to make large-scale releases of water to surge down the river towards Brisbane. Worse, they covered it up.

Pretty soon, some Queenslanders, and perhaps the whole editorial department of The Australian, will convince themselves that the flood would not have happened at all had it not been for the miscreant engineers. But for them, perhaps, it might not have even rained.

No doubt there will be some insurance companies who will be keen about such findings, because they provide the insurance industry with someone with deep pockets able to mitigate their extensive losses - losses no doubt the greater for the way that they were cajoled, by various politicians, to abandon theological distinctions between storm, flood and water damage.

If the engineers were responsible, or negligent, then presumably the Queensland Government is vicariously responsible for the damage they caused. If this is so, the Commonwealth Government, under national disaster arrangements, will have to pay. This on top of the billions we have already paid - mostly for the damage caused to dwellings built on land that was flooded in 1974 and which the Brisbane city fathers swore then would not be built on again.

It is possible, with hindsight, to think that those managing dam outflows made the wrong decision. Had they let water out earlier, Brisbane would have been flooded earlier, and, probably, for longer, but, possibly (and it is not possible with the data we have at the moment to be certain of this) the floods might not have been that high. If the floods were higher as a result of bad judgments, it would probably have increased damage by about 10 per cent at most. Which is to say that most of the damage would have occurred anyway - with non-Queenslanders footing the bill anyway. There's no discount for contributory negligence, however wanton.

In defence of the engineers, it might be said that the circumstances were for them quite new. The inundation of Brisbane by the continuous rain was always virtually inevitable, regardless of what they did, and it was never entirely clear just how the existence of the dam changed the water dynamics. Had they let water go unnecessarily, causing a flood that might otherwise not have happened, they would be copping just as much criticism today.

We see much the same second guessing of bushfire controllers, and people searching for earthquake victims, with some criticism reaching the point of implying the whole disaster might not have happened had a person doing his or her best under high pressure made a different judgment call.

With disasters, after we congratulate ourselves for surviving, then praise the courage of some and our charity, we hunt for people we can blame. If human agency must be criticised, I wouldn't focus on the engineers, that's just too easy. It's the poor (the sort who buy cheap land on floodplains), white-shoe brigaders who take advantage and build them houses, and city planners, politicians and urgers, who caused the Brisbane flood disasters. Now we are getting ready to allow them to do it again.

Nothing that the Commonwealth, with its vast and growing disaster bureaucracy, and endless meetings focused on the ''learnings'' from such fiascos, is calculated to stop it. Practical matters like maps, and psychic matters like making politicians sensible, are not in their remit.

Jack Waterford is editor-at-large.