Tag Archives: floods

May Day mayday! A tale of extraordinary weather and extra-ordinary lasagne.

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It’s been a long time between posts. As per the forecast, my PhD has reduced this blog from a bubbling stream to a lifeless dry creek bed. But any stream can be revived with a little rain. And with a lot of rain, it all comes flooding back.

'UQ Falls' - posted to the Facebook group UQ StalkerSpace by Panashé Machinguara just after midday on 1 May 2015.

‘UQ Falls’ – posted to the Facebook group ‘UQ StalkerSpace’ by Panashé Machinguara just after midday on 1 May 2015.

‘A lot of rain’ is one way to describe what Brisbane experienced on Friday the 1st of May, 2015. ‘Extraordinary weather event’ would be another. The gauge in the CBD recorded 182mm of rain in the 24-hour period from 9am that morning. To put that in perspective, the historical average rainfall for the entire month of May is 74mm. The record for the largest daily fall at this time of year stands at 190mm on 26 April 1989, but the recent event set a new daily record for May, with the previous record being 149mm on 9 May 1980.1

Personally, I’d had enough of the rain long before any records were broken. My trip into the University of Queensland at St Lucia that morning took nearly two hours because of a track fault somewhere near Yeronga Station. ‘Local flooding’ was said to be the cause. I enjoyed the rain a lot more from the other side of my office window, but was forced to venture out again at around 4pm. By that time, every road and pathway on the campus was a raging torrent. Continue reading →

Notes:

  1. All of this rainfall data is available from the Climate Data Online section of the Bureau of Meteorology website. The historical data comes from the the Brisbane Regional Office station (040214), which operated from 1840 until 1994, while the more recent data comes from the Brisbane station (040913), which commenced operating in 1999. ↩

The Western Creek floodgate: a reality after 125 years

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Way back in January, I reported that the City Council had begun constructing a floodgate at the mouth of Western Creek. This is the spot where the Milton Drain meets the river, right next to where the dilapidated shell of the old floating restaurant still stands. If you have passed by this spot in the last few months, you will have seen that the construction is complete: Western creek finally has its floodgate.

Hugh Bell's letter to the editor of the Brisbane Courier in July 1889, arguing for the use of tidal valves to prevent flooding in Milton and Rosalie.

Hugh Bell’s letter to the editor of the Brisbane Courier in July 1889, arguing for the use of tidal valves to prevent flooding in Milton and Rosalie.

I say ‘finally’ not because more than three and a half years have passed since the 2011 flood (some people might even call that response time quick), but because more than 125 years have passed since a floodgate at the mouth of Western Creek was first proposed. In July 1889, while the mud was still drying from a flood that peaked at 3.75m on the Port Office gauge (about 2 ft lower than the 2011 flood), a Milton resident named Hugh Bell wrote to the Brisbane Courier, asking “Why are not tidal valves or flood gates being used” to prevent flooding in Milton, Rosalie and other low-lying suburbs? This question was no doubt raised again in March of the following year, when the river peaked at 5.33m — just under the mark of the 1974 flood. In response, the Toowong Shire Council in October 1890 unveiled an ambitious whole-of-shire1 drainage scheme which featured floodgates at the end of Western Creek and Langsville Creek. But the council could not afford to build the whole scheme, and so built it piecemeal instead. Some components, such as the drain through Red Jacket Swamp, took years to get finished, while the floodgates never materialised at all.

But the idea didn’t die: it resurfaced after every flood, only to recede again with the memory of the floodwaters. It probably sunk into near-oblivion after the completion in 1985 of Wivenhoe Dam, which — if you believed the real estate industry — was supposed to save Brisbane from ever flooding again. But when the flood in January 2011 proved — unless you believe the real estate industry — that Wivenhoe Dam is not a bottomless pit after all, attention turned once again to more localised methods of flood mitigation. The Brisbane City Council commissioned a study into backflow prevention, and since 2012 has been rolling out the installation of floodgates — more properly known as backflow prevention devices — at prioritised spots along the river. Continue reading →

Notes:

  1. The Toowong Shire fronted the river all the way along the Milton Reach, from Boundary Creek (where Boomerang Street is today) to Toowong Creek (near Gailey Road). The boundary between Toowong and Ithaca shires began where the railway line crossed Boundary Creek, and continued along the railway until it reached Baroona Road, then known as the Boundary-road because it divided the two shires all the way up to the top of what is still called Boundary Road today. (Back then, Baroona and Boundary roads were joined at the upper end of Norman Buchan Park.) ↩

A floodgate for Western Creek

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A sign announcing the construction of a backflow valve at the mouth of Western Creek.

A sign announcing the construction of a backflow valve at the mouth of Western Creek. It is erected on the gate to the footbridge under Coronation Drive. (Photo: S. Cowley)

So, it’s really happening. If this sign is to be believed, then Western Creek is finally going to have its floodgate. The photo was snapped at the entrance to the footbridge under Coronation Drive at the mouth of Western Creek (otherwise known as the Milton Drain) a few weeks ago by Steven Cowley, who has been my eyes on the ground at Western Creek ever since I moved to the southside last year.

The sign doesn’t mention a floodgate, but that is essentially what the ‘devices to be installed’ as part of the ‘Backflow Program’ are. They are contraptions of varying designs that ‘mitigate river water from flowing back up stormwater pipes when the river is in flood’. Such devices have already been installed just downstream near Cribb Street and the Go-Between Bridge. The City Council’s website has a page listing all of the places where backflow devices have been, or might soon be, installed. The page also provides links to the technical reports about these devices that the council commissioned in the wake of the 2011 flood. Continue reading →

The legend of the lost lagoon

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If you’ve read my earlier post about the Waters of Milton, then you will have already encountered this story, but I’d like to give it a post of its own. It’s the story of a lagoon that existed in the area bounded by Cribb Street, Park Road, Coronation Drive and the railway line — just outside the catchment of Western Creek. The lagoon stretched diagonally across this area from just near the Suncorp Bank on Park Road to where Cribb Street meets Coronation Drive.

The image below shows how the lagoon was depicted by the surveyor James Warner in 1850 on what is possibly the earliest map of the area. Immediately below the map is a screenshot from Google Earth, into which I imported an overlay of Warner’s map. It doesn’t exactly stand out, but if you look closely you can see the lagoon stretched across the modern landscape. In the background, you can also see Boundary Creek snaking through the Coronation Drive Office Park and past Suncorp Stadium.

The lagoon between Cribb Street and Park Road, Mitlon, as depicted in 1850.

A lagoon between Cribb Street and Park Road, Mitlon, as depicted in 1850.

The lagoon that once stretched between Cribb Street and Park road, as depicted on a map from 1850.

The lagoon that once stretched between Cribb Street and Park road, as depicted on a map from 1850.

Continue reading →

Are we learning yet?

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A story in the Brisbane Times this morning, titled Buyers less fearful of flood zones, made me a little bit mad.

Though I try not to buy into the blame game around the 2011 flood, I suspect that the real estate industry is partly responsible for the false sense of security that set in after Wivenhoe Dam was built. I have no proof of this; it is just a hypothesis. But it stands to reason that someone whose job is to sell houses will downplay the risks of flooding any way they can. Buyer beware.

Whether or not real estate agents have done it in the past, they certainly seem to be doing it now.

According to agents working in river precinct suburbs, the percentage of buyers willing to consider properties previously flooded in 2011 has increased significantly because they feel assured that the Wivanhoe Dam did its job in mitigating another flood over the Australia Day weekend.

Granted, this boost in buyers’ confidence is not necessarily the doing of real estate agents. People make their own assessments of risk based on events, and make their own decisions accordingly. Whether those assessments and decisions are justified or wise is an open question, but it is one that needs to be answered with some understanding of the facts about the 2011 and 2013 flood events, what role the dam played in each, and how the two events are comparable. I won’t pretend to have all of those facts. But I humbly suggest that not many real estate agents do either.

The article continues, quoting Brad Robson of Brisbane Real Estate:

“They’re happy that the dam worked. There was a truckload of rain and nothing flooded so it’s given them the confidence to go ahead and make a purchase”

John Johnston, of Johnston Dixon, said the Brisbane River needed a proposed class action by residents to succeed in order to clear its name.

“These properties should never have experienced the flooding that they did in 2011 and the latest weather event last month supports that,” he said.

“The mitigation capacity of the Wivanhoe have now been proven. I’m confident that if this class action goes through, it will largely clear the Brisbane River’s name and buyers will no longer be afraid to purchase near the river.”

Torwood Street during the January 2011 flood

Torwood Street during the January 2011 flood

There you have it: the smallness of the 2013 flood proves that the 2011 flood did not need to happen. It was all the fault of the dam operators. They are guilty, and the river is innocent — we just need to ‘clear its name’!

I’ll stress again that I do not know all of the relevant facts. But in case someone else has the inclination to go do some homework, I suggest that the following questions would be a good place to start:

  • Could it be that the 2013 flood was smaller than the 2011 flood because there was less rain?
  • Where did the “truckload of rain” that fell in 2013 actually fall? According to our Premier and the Bureau of Meteorology, the flooding in 2013 was caused by rain that fell in catchments that discharge to the Brisbane River downstream of Wivenhoe Dam. Suppose that even more rain (a shipload?) fell in those catchments: would the dam save us then?
  • Could there be any truth in the Flood Commission’s finding, stated on page 524 of the Commission’s final report, “that, allowing for the limits of the strategies in the Wivenhoe manual, the flood engineers achieved close to the best possible flood mitigation result for the January 2011 flood event”?

I’m not presuming that the dam manual is perfect, that the dam operators did a perfect job, or that there are not lessons to be learned from the way the 2011 flood was managed. And I’m not offering an opinion on whether a class action against the government’s management of the flood is warranted. But I do think that comments such as those above from the real estate industry are grossly irresponsible, and are the absolute last thing we need if we are to to learn from past events and become better informed about the nature of flood risks in Brisbane.

Buyer beware.