Hunter superstorm not as freakish as we think

Two things should be said. We can do something about such events, and we should. They are to be learned from and used in ways that help ensure that the extreme consequences they bring are mitigated. And in any case they are probably not as freakish as we think they are.

Take the case of fishermen who are washed off rocks along the coast and killed. It happens a lot, a few times in the average year in NSW, and the waves that take them are routinely described as freak. The truth is that such waves might happen every day or week. Every now and then an unusually big wave comes along, but it is not accurate to call it a freak. They’re actually quite common. 

The rain that fell on Maitland was certainly very heavy, perhaps even extreme. There were 148mm measured by the official Bureau of Meteorology rain gauge in Maitland in one hour, between 10am and 11am on that Tuesday morning. There were 242 mm in the six hours from 9am to 3pm that day, and 408mm in the 48 hours ending at 9am on the 22nd. And the vast bulk of that rain fell in only a portion of the 48 hour period – more than half of it, in fact, in only six hours and more than a third in that single hour.

Are these falls unprecedented? Almost certainly not. I have not delved into all the records, but I have become aware of a rainfall event that is said to have occurred in March 1893 at Morpeth (the month of one of the most severe floods ever seen on the Hunter). There, it is claimed, 29 inches (635mm) fell in 25 hours. That is by any standard very heavy rain, and it obviously persisted for a long time. But (if that figure is accurate) the average intensity was actually lower than that recorded in those one- and six-hour periods in Maitland on 21 April. Doubtless there were short periods of higher intensity in the 1893 event than the average of roughly 22mm per hour, and it may be that there was more than 148mm in a single hour at some stage. We can’t know. But we can know that rainfall and river-height records are being broken all the time. In the first 10 months of 2007, a year of drought in much of Australia, rain and flood-height records were broken at places in six of the eight states and territories of Australia. Extreme events are common.

They are just not common in the same location. Nevertheless the Brisbane and Maitland areas both had big rain events within 10 days of each other in late April and early May. And the likelihood is that Maitland has had a number of events of the sort that it has just experienced.

Why should we not call such things freak events? Because that lays the groundwork for dismissing them as unfortunate but not events we should be concerned about. But we should. Does it mean that some of the places where flooding occurred in Maitland should not be further built upon? Are there similar locations in which development is likely in the future where we should think again? Do the little valleys into which sheets of water flowed need bigger drains to cope with what they will occasionally have to contend?

The Chinese have a saying: “If you can’t describe something accurately, you don’t understand it.” 

And from that, it might be added, you can’t manage its consequences properly, including recognising that something similar might need to be dealt with again and perhaps before long. And this line of reasoning goes further. The 1955 flood, thought to have been of a magnitude that would occur only once in about 200 years in Maitland, has a 0.5 per cent chance of being experienced here in each and every year. It was no freak, and one can argue that it should be central to our land use planning. Yet many people in Maitland think that a flood of the magnitude of the 1955 flood will never happen again.

Sadly, it will. Flood records are broken frequently and there’s no reason to think they won’t continue to be broken. And the excellent levee scheme that protects Maitland’s built-up areas on the floodplain are not designed to keep floodwaters out in a really big flood. Even the 1971 flood, the biggest experienced here since 1955, was only just kept at bay. And that flood has been defined as one which would occur at the Belmore Bridge gauge once in about 20 years, on average. 

Note the use of the term ‘on average’ there. It doesn’t mean regularly every 20 years. 

We should count ourselves lucky to have experienced only one flood of the scale of the 1971 event in the last 60 years. And nothing like February, 1955.

Maitland and its environs have just had a flood. In the scheme of things it was not a bad one, but there was a death and property losses as well. It makes this an appropriate moment to examine the record of the City Council in flood management.

Let's take the long view. As it happens the original West Maitland Council, formed in 1863, was quickly involved in flood mitigation. It built and armoured with rocks the levee along the riverbank parallel to High St. Over the decades this bank was overtopped or failed less frequently than the farmer-built levees like the Cummins, Jenkins and Eckerts 'dams' upstream.

And the council gradually built up the low points along High St, the main thoroughfare and route to the inland. Low points had flooded frequently and were an impediment to movement along an important highway, and they were raised so that in due course High St had a more or less constant upward gradient from about Smith St to Elgin St. The council performed the flood mitigation task well, according to the standards and styles of the day.

But the levees were found out in the great flood of 1955. There were numerous failures, and the consequences were catastrophic. The state government took over the flood mitigation role in the Hunter Valley with the management assistance of the Hunter Valley Catchment Management Trust.

A strong program of flood mitigation was instituted. Many levees were built according to modern engineering standards (with spillways to 'train' flood flows around built-up areas), drains dug, buildings removed from floodways, dwellings raised so that their floors were above all but very big floods and new dwellings subjected to regulations governing minimum floor heights.

Maitland was one of the great beneficiaries of these efforts. It got a strong measure of protection from flooding, more heavily subsidised by the state and federal government than was the case outside the Hunter Valley. The state also restricted residential development in central Maitland, incorporating South Maitland, Horseshoe Bend, part of East Maitland and the streets joining High St, all of which had been grievously hit by the 1955 flood and in many other floods.

The restriction prevented the problem of the community's flood vulnerability from getting worse. In earlier times, growth had meant more and more dwellings being exposed to the ravages of flooding. Checking residential development on the floodplain put an end to that.

Moreover the restriction helped to preserve the magnificent architectural heritage of High St from falling victim to the wrecker's ball during the 1960s and 1970s. By the late 1970s, heritage legislation protected several important High St buildings which might easily have been lost.

But the Maitland City Council chafed at the restrictions on residential development. It felt that the city's progress was being denied, and it resented its reputation as a 'flood city'. It preferred to be known as the 'Hub of the Hunter.'

This came out in interesting ways. In 1963 the Council commissioned a history of Maitland to commemorate 100 years of local government. That book failed to mention the 1955 flood, surely the most momentously disastrous event in Maitland's history. The omission cannot have been accidental: eight years after the flood no self-respecting historian could have ignored it. Riding instructions must surely have been given. Maitland's history was distorted, and it seemed to be Council's doing.

Years later, in 1982, the Public Works Department fixed about a hundred flood markers to power poles throughout the flood-liable areas of Maitland. They indicated the heights reached in 1955.

And what has happened to them? They have almost all disappeared, the victims of souvenir hunters, people wanting to protect property values, power pole replacement and the rusting of the nails that fixed the markers in place. Council could have maintained them, but it seems to have passively awaited their disappearance.

Here it appears to be at cross purposes with the State Emergency Service which wants to encourage residents to plan for future floods. The markers gave people a clue about the flood threat they might one day face. They constituted inexpensive, easily maintained reminders of how bad flooding has been and were an aid to flood preparedness activity.

In their place the council has permitted three large billboards which draw attention to the flood mitigation scheme. These are in effect advertisements for the state government's floodplain management. They say nothing about how high flooding has got in Maitland's history. Are they just cynical replacements of the markers, which were feared because of an unsubstantiated, over-stated concern about property values?

These are two cases of council not doing the best job in relation to flood management over the past few decades. The book minimised the importance of flooding, and the loss of the markers makes it difficult for current residents, many of them nowadays without personal knowledge of past floods, to visualise a bad one.

On these matters council slipped away from good practice. Was it was worrying more about the city's reputation, investment and progress than about the safety of the community?

After all, flooding remains a problem. The levees are not designed to keep floods of the magnitude of the 1955 event (or even floods rather smaller than that one) out of the built-up areas of South Maitland, Horseshoe Bend, the streets adjoining High St, Lorn and the low-lying parts of East Maitland. Maitlanders might legitimately question the priorities of Council over the decades.

Recently the Maitland City Council, worried about the ageing housing stock of its oldest areas and about a malaise which has developed in the Central Business District, adopted a strong program of redevelopment for central Maitland. After many years the floods-based restriction on new housing there has been lifted. Central Maitland is once again ripe for residential development. The council plans that by 2031 the population of the area will rise from its present 1800 to its pre-1955 level of 5600.

And, having won a sizeable federal grant, council seeks to revitalise the CBD. This is what The Levee Project and the beautification and modernisation of High St are about. And an increased population nearby will restore the CBD's market and thus promote its commercial viability.

That is all to the good. Council's ambitions for the CBD are admirable.

But one must wonder at the way it is pursuing urban revitalisation. A case can be made, given that flooding of central Maitland remains an occasional inevitability, that the result will be the restoration of the flood vulnerability of the past. Some might say that the council is pursuing a policy of 'planned isolation', or even 'deliberate entrapment', of future residents, when the next big flood strikes.

This has barely been mentioned in public discourse over the past five years.

One day, central Maitland will be flooded again. Its mitigation scheme has performed admirably for decades, but it is not designed to keep out floods of the magnitude of the 1955 one (or even rather smaller floods than that). A flood not much larger than the flood of 1971 will be capable of invading the low-lying areas of South Maitland, Horseshoe Bend, East Maitland and the streets adjoining High St.

When that happens some people will refuse to evacuate, as happened in 2007. Those residents will be sitting above floodwaters without power, working landline phones, functioning sewerage and the ability to charge their mobiles. They will tire of that, and the State Emergency Service will be required to organise their rescue, probably through floodwaters with localised dangerous velocities near buildings.

Could council's developmental goal be at cross purposes with the SES here? Is it placing unreasonable demands on a volunteer organisation to keep people safe?

The SES has no doubt been consulted on this. But the correspondence is confidential and we have no way of knowing what the SES was told about council's plans. Nor do we know how the SES responded. Can the streets move the volume of evacuation traffic in the time available before the streets become impassable due to flooding?

Doubtless council is doing what is required by the state's Floodplain Development Manual, a document that was once considered a leader in the field. But in recent times the manual has been diluted to reduce 'impediments' to development. In highly flood-prone Maitland, might more than the minimum standards of the manual be needed in the interests of community safety? How much effort will go into educating new residents about the risk of flooding? What will be done to ensure they evacuate when a big flood is bearing down on Maitland? Will the standard 'freeboard' applied to floor levels be enough?

The Council's approach to central Maitland illustrates what is known as the 'levee paradox'.

A community tires of inundation, levees are built and the community comes to believe that the flood problem has been solved. Development is intensified behind the levees - more dwellings, more commerce. Then the levees are overtopped or breached, and there is more to be damaged and lost, including lives, than was the case previously. Maitland's history has illustrated the paradox before, and it is likely to do so again. But this is not recognised.

For half a century, it seems, successive councils have played down the greatest environmental threat that Maitland faces. Council has a history of ignoring recommendations made by its Floodplain Management Committee. Its community flood education has been more confusing to residents than enlightening. It has appeared to allow residents to believe that the levees give them ultimate protection from floods. It has not maintained the flood markers which indicated the levels reached in 1955.

And it promotes urban development in places that are cut off in floods. Gillieston Heights is

the obvious example. In that case Council could have sought to ensure that the access road was built higher, with culverts underneath, and with guard rails installed to stop cars being washed into floodwaters. Yet again it appears to be at cross purposes with the SES, which has to bear the risks and the workload associated with the now considerable resupply task when Gillieston Heights is cut off.

This writer does not believe that no development in central Maitland should be permitted, and he recognises the plight of the CBD, the aging housing stock, and the work Council has done on urban drainage. But he does wonder whether its approach to Maitland's future properly addresses the risks which flooding will bring.

Flood prone Maitland has a history of councils which have grappled with the problem of flooding. But not everything that has been done is necessarily up to the highest standards possible.

Does the present council value development more than community safety? One might, at least, wonder at the balance that has been struck between these goals.

* Chas Keys is a former Deputy Director General of the NSW State Emergency Service, an Honorary Associate of Risk Frontiers at Macquarie University and the author of Maitland, City on the Hunter: fighting floods or living with them? published by the Hunter-Central Rivers Catchment Management Authority