Queensland Floods

Surely one of the most incongruous sights amongst the volunteers helping with the clean up was the Gold Coast meter maids in their usual attire plus gold-painted elastic-sided boots.

gumboot said:
I'm not sure how releasing more water into the Brisbane valley would have resulted in less flooding...

Aside from which the Brisbane River isn't the only catchment area that suffered severe flooding. Nothing they could have done with that dam would have affected the other flood areas.
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It's the timing, as I understand it. Operation of the flood gates looks like a high wire juggling act to me, what with taking into account actual and anticipated inflows to the catchment and the rivers downstream, plus the effect of high tides.
 
gumboot said:
I'm not sure how releasing more water into the Brisbane valley would have resulted in less flooding...

Aside from which the Brisbane River isn't the only catchment area that suffered severe flooding. Nothing they could have done with that dam would have affected the other flood areas.
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The quantity of water coming into the dam was more than the dam could contain. If they hadn't released the water, there were 'fuses' that would let the water out anyway, but then they would have had no control over that process. The dam was just not big enough to hold all the water coming in. It was built to cope with the 1974 flood, but this flood was about 50% bigger again.
 
a_unique_person said:
The quantity of water coming into the dam was more than the dam could contain. If they hadn't released the water, there were 'fuses' that would let the water out anyway, but then they would have had no control over that process. The dam was just not big enough to hold all the water coming in. It was built to cope with the 1974 flood, but this flood was about 50% bigger again.
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Yes I know, but they did release water and they did maintain the level on the dam. What I'm scratching my head at is those apparently suggesting they should have released more.

The entire point of using a dam for flood mitigation is to release as little water as you possibly can.
 
gumboot said:
Yes I know, but they did release water and they did maintain the level on the dam. What I'm scratching my head at is those apparently suggesting they should have released more.

The entire point of using a dam for flood mitigation is to release as little water as you possibly can.
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The dam was sold as a water business. It's job is now to sell water, for a profit, and mitigate floods. Which is an inherent dichotomy in it's existence. There are rules, which are supposed to balance it's water level between the two functions. When it is 100% full for water provision purposes, it is physically about 50% full. What they couldn't predict was that the last downpour was going to be an extreme one, and one that was placed in exactly the right place to cause the most damage, at the same time as extreme tides were coming the other way. Considering the fact that the volume of water it faced was much more than the 74 flood, which it was designed to protect against, it did a pretty good job, the floods would have been much worse otherwise.

But Queensland is in big trouble now, it has massively increased it's population, which needs water, there is a big agricultural industry that needs water, there has just been the most extreme drought in history. What do they do? Leave the dam empty? Try their luck again and aim for half full?

At the same time, there has been flooding over an area of about 500,000 sq km in Queensland alone. I don't know how many NZs you could fit in there. Then those floods extended to NSW and Victoria as well. It has been extraordinary. This is being called the biggest natural disaster in Australia's history.

This is happening against a backdrop of global warming, the tides now are that bit higher, the warmer atmosphere can hold more water, the La Nina is that bit stronger. It doesn't cause a flood, they happen from time to time, but it makes them that much more of a risk.
 
a_unique_person said:
The dam was sold as a water business. It's job is now to sell water, for a profit, and mitigate floods. Which is an inherent dichotomy in it's existence. There are rules, which are supposed to balance it's water level between the two functions. When it is 100% full for water provision purposes, it is physically about 50% full. What they couldn't predict was that the last downpour was going to be an extreme one, and one that was placed in exactly the right place to cause the most damage, at the same time as extreme tides were coming the other way. Considering the fact that the volume of water it faced was much more than the 74 flood, which it was designed to protect against, it did a pretty good job, the floods would have been much worse otherwise.

But Queensland is in big trouble now, it has massively increased it's population, which needs water, there is a big agricultural industry that needs water, there has just been the most extreme drought in history. What do they do? Leave the dam empty? Try their luck again and aim for half full?

At the same time, there has been flooding over an area of about 500,000 sq km in Queensland alone. I don't know how many NZs you could fit in there. Then those floods extended to NSW and Victoria as well. It has been extraordinary. This is being called the biggest natural disaster in Australia's history.

This is happening against a backdrop of global warming, the tides now are that bit higher, the warmer atmosphere can hold more water, the La Nina is that bit stronger. It doesn't cause a flood, they happen from time to time, but it makes them that much more of a risk.
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AUP, Wivenhoe is operated by SEQ Water which is a state-owned statutory authority.

It will be interesting to see if the inquiry recommends changes to the relative proportions of the dam's water supply and flood mitigation compartments, at least during La Nina events. (Hopefully some of our politicians might get a clue also - see the Queensland Times article linked by D2011 where the State opposition earlier condemned releases from the dam once it reached 100% capacity.)

Re SE Qld's water supply, we do have a "water grid" that can bring on line water from the desal and recycling plants to supplement supply during drought. But you're right that population growth, which is mostly in SE Qld, is a cause for concern.

As to the dam's operation before and during the flood, the argument that was made in one of the articles that D2011 linked (i.e. that SEQ Water should have released more water over the weekend before the flood) hasn't gained much traction outside the pages of The Australian's. The engineer cited turns out to be a chemical engineer with no expertise in dam operation. (There's more detail in this Brisbane-based blog post and comments.)
 
From the opposition leaders website.

Time to rethink use of Wivenhoe’s capacity

March 9, 2010
Wivenhoe Dam’s true capacity was double that being reported and better management of the storage was needed to limit further waste of taxpayers’ money on grids and desalination, the State Opposition said today.
LNP water spokesman Jeff Seeney said reports that Wivenhoe was over 90 per cent full were misleading because at ‘100 per cent capacity’ the dam was less than half full.
Mr Seeney said a 2005 government report showed using just 2 metres extra of Wivenhoe’s storage would add an extra 228,000 megalitres of water and provide an extra ‘no fail’ yield of 31,000 megalitres a year to SEQ’s water supply – equivalent to the total annual yield from a properly functioning Tugun desal plant.
Built in the late 1970s in response to the 1974 floods that devastated Brisbane, Wivenhoe was constructed to hold not just a large water supply, but also act as a flood buffer to help to manage future flooding in Brisbane.
Wivenhoe’s ‘full storage level’ was 1.15 million megalitres – only 44 per cent of total capacity of 2.6 million megalitres.
Mr Seeney said it was time to review management policy so more of the dam could be used for water storage to reduce chances of another water crisis.
“Obviously the dam needs to maintain the flood buffer for Brisbane and any decision on storing extra water will impact on the effectiveness of the dam’s flood buffer role.
“But we need to determine whether the balance that was struck in the early 1980s remains appropriate for the situation today. Much has changed since 1980 … Brisbane and Queensland generally have experienced long periods of low rainfall which saw the real possibility of Brisbane running out of water.
“Since those original decisions were made in 1980, technology has advanced and we are now able to forecast rainfall events far more accurately. Automatic stream flow monitors and advanced models allow for much better decision making in managing any potential floods.”
Mr Seeney called on the Minister to ensure no water was released from Wivenhoe until a proper review of storage policy was undertaken.
“It would be absurd to release water from Wivenhoe until all options are thoroughly investigated,” Mr Seeney said.
“Labor has seriously mismanaged water for many years, brought Brisbane to the brink of running out of water …and blown billions of dollars in a panic on projects that are hideously expensive and grossly inefficient to run. We need to do a lot better.”
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http://www.jplangbroek.com/time-to-rethink-use-of-wivenhoes-capacity/


Food for thought.
 
a_unique_person said:
From the opposition leaders website.




http://www.jplangbroek.com/time-to-rethink-use-of-wivenhoes-capacity/


Food for thought.
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That is a good example of why politicians ought to be kept away from dam operation! Seeney was still on this hobby-horse in October when we were into a La Nina and Wivenhoe was releasing water. (Apparently Bjelke-Petersen wanted politicians to be able to have a say in when water should be released from the dam. Fortunately the then water commissioner stood up to the old coot.)

Interesting flood special on the 7.30 Report last night. It featured a forum of Graceville residents and emergency/Red Cross/Lifeline responders. Graceville went under in the '74 flood but it seemed that some residents accepted the conventional wisdom that Wivenhoe had effectively flood-proofed Brisbane.* This despite Lord Mayor Campbell Newman, at the start of the wet season, rather forcefully pointing out that Brisbane could face another flood on the scale of 1974, and that he didn't want to hear people complaining about not having flood insurance. The Council had also been spruiking its flood maps for ages.

And speaking of flood maps, at least these floods will leave a legacy of more comprehensive data about flooding. Apparently some insurers don't offer cover for riverine flooding because of a lack of data. Suncorp, Queensland's largest insurer, did their own flood mapping and are supposedly the only insurer that includes comprehensive flood coverage in all home and contents policies.

*I must admit I thought this too until last year. In my defence, my area isn't affected by the river flooding and consequently I didn't examine this assumption too closely.
 
Getting a perfect illustration of Australia's particular vulnerability to flooding at the moment. As we speak the North Island of New Zealand is being hammered by phenomenal amounts of water - the Metservice is forecasting an additional 400mm in the next 24hrs for some areas. That's substantially higher rainfall that experienced even in the Toowoomba flash-flood event. Although we're suffering from some pretty bad flooding ourselves it's nothing like in Australia and highly unlikely to get that bad - our biggest problem is likely to be slips causing road closures.

And the reason for this is one of geography. We have a fairly steep hilly country and we're an island nation - the furthest inland point in the North Island is about 114km from the nearest coast (ironically, this point is located on a peninsula on the shores of Lake Taupo and is surrounded by water on three sides!). Our rivers run very fast normally, rising very rapidly even under minor rainfall and drop away rapidly again. As a result, not only is there little option for widespread flooding, but because our rivers "flood" as a matter of course we tend not to build near them.
 
Sex doll floatation device
Newspix / Rex / Rex USA
An Australian couple found an exciting new use for a blow-up doll when they turned an inflatable sex toy into a raft. But they had to be rescued when the woman lost her grip on the doll in the rough waters of the Yarra River outside Melbourne on Sunday.
So the world has been watching, which makes it even more embarrassing for the two Australian teenagers who were rescued from floodwaters while clinging to an inflatable sex doll near Melbourne. The young man and woman were attempting to float downriver on the sex toy, but the woman had to be rescued by a kayaker when she wasn't able to maintain her position on the pornographic life raft. The man, of course, showed remarkable agility in remaining on top of it. Rescuers managed to save both victims, wrapping the woman in a blanket and giving the man a cigarette and a TV remote.

And forgive us our trespasses. Everyone else gets a stern warning from a deputy.
 
gumboot said:
Getting a perfect illustration of Australia's particular vulnerability to flooding at the moment. As we speak the North Island of New Zealand is being hammered by phenomenal amounts of water - the Metservice is forecasting an additional 400mm in the next 24hrs for some areas. That's substantially higher rainfall that experienced even in the Toowoomba flash-flood event. Although we're suffering from some pretty bad flooding ourselves it's nothing like in Australia and highly unlikely to get that bad - our biggest problem is likely to be slips causing road closures.

And the reason for this is one of geography. We have a fairly steep hilly country and we're an island nation - the furthest inland point in the North Island is about 114km from the nearest coast (ironically, this point is located on a peninsula on the shores of Lake Taupo and is surrounded by water on three sides!). Our rivers run very fast normally, rising very rapidly even under minor rainfall and drop away rapidly again. As a result, not only is there little option for widespread flooding, but because our rivers "flood" as a matter of course we tend not to build near them.
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The distance from Wivenhoe to the coast is not much different to that, only 74km by road to the sea. In contrast, it has been built on.

The Victorian floods are slowly moving North, away from the sea, where they will meet the Murray and then head West of over 700km, till they get to the sea, if you start at Horsham,
 
a_unique_person said:
The distance from Wivenhoe to the coast is not much different to that, only 74km by road to the sea.
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Actually I think you can use the Brisbane River to demonstrate my point. The Brisbane River is only a small part of the affected flood area, but like most rivers in Australia it has a large catchment area relative to its length and is very low-lying, both of which contribute substantially to flooding.

The river's about 340km long, with a catchment of 13,600km2 and a maximum elevation in the catchment area of 868m.

If we compare New Zealand, the mean elevation of our entire country is 430m! The largest river in the North Island - the Waikato, is longer than the Brisbane at 425km, but its catchment is only fractionally larger at 13,700km2. Its maximum elevation is almost 2,800m!



a_unique_person said:
The Victorian floods are slowly moving North, away from the sea, where they will meet the Murray and then head West of over 700km, till they get to the sea, if you start at Horsham,
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Lot a land between them and the sea to be flooded... :(
 
gumboot said:
Actually I think you can use the Brisbane River to demonstrate my point. The Brisbane River is only a small part of the affected flood area, but like most rivers in Australia it has a large catchment area relative to its length and is very low-lying, both of which contribute substantially to flooding.

The river's about 340km long, with a catchment of 13,600km2 and a maximum elevation in the catchment area of 868m.

If we compare New Zealand, the mean elevation of our entire country is 430m! The largest river in the North Island - the Waikato, is longer than the Brisbane at 425km, but its catchment is only fractionally larger at 13,700km2. Its maximum elevation is almost 2,800m!





Lot a land between them and the sea to be flooded... :(
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I have seen some NZ rivers, and they are different to the typical Australian river. The water is clear, for one thing.:o
 
gumboot said:
Actually I think you can use the Brisbane River to demonstrate my point. The Brisbane River is only a small part of the affected flood area, but like most rivers in Australia it has a large catchment area relative to its length and is very low-lying, both of which contribute substantially to flooding.

The river's about 340km long, with a catchment of 13,600km2 and a maximum elevation in the catchment area of 868m.

If we compare New Zealand, the mean elevation of our entire country is 430m! The largest river in the North Island - the Waikato, is longer than the Brisbane at 425km, but its catchment is only fractionally larger at 13,700km2. Its maximum elevation is almost 2,800m!





Lot a land between them and the sea to be flooded... :(
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I think the flooding will stop at the Murray-Darling meeting point.
 
Flood inquiry wraps up public hearings

Updated Sat May 28, 2011 10:31am AEST

The Queensland flood inquiry has completed its first round of public hearings, but its work is far from over.

The commission now has two months to prepare its interim report into the summer disaster. Commissioner Justice Catherine Holmes will issue the parties with summaries within a fortnight and they will then have two weeks to respond. She has asked them to confine their responses to what is strictly necessary.

The final report deadline has been extended until February because of the volume of material to be examined.​


ABC News​
 
...and the Right Honourable Commission has determined that the cause of the flooding was...





...rain.
 
HawaiiBigSis said:
No doubt.

Is that the popular opinion, as well, or do people feel the government should have protected them somehow from a natural disaster?
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Generally, people are realistic enough to understand that there is little any government could have done in terms of prevention of the event(s), although there have been numerous submissions with regard to to the lack of warning given to some residents. It would be premature of me to try and predict what the Commission will say about this, although as is always the case I have no doubt that part of the finding will be that "more might have been done".

An example of the sort of things that the Commission is looking at in this regard:

Hydrologist testimony

The inquiry has also questioned whether residents at Grantham could have been better warned before water tore through the Lockyer Valley town in January.

Queensland's chief hydrologist Peter Baddiley is the final witness to take the stand before the inquiry adjourns. Mr Baddiley was asked to comment on suggestions that Grantham could have been better warned about the flash flood that hit the community.

He told today's hearing he was not "sure who knew Lockyer Creek could do such a thing at Grantham, as opposed to the normal flash flood where you need to move a car".

He said in the absence of a full flash flood warning system in the catchment, more could not be done.

In his written statement to the inquiry, Mr Baddiley said he completed modelling about large releases when Wivenhoe Dam, north-west of Brisbane, was at its top flood alert in January. He predicted discharges of 10,000 cubic metres of water per second would have caused a flood the size of Brisbane's record 1893 event. Based on that advice, the dam operator scaled back its release.

Mr Baddiley also said in his statement large floods like those of the last summer provide less time for forecasting and warning and that should be considered in designing an operational response.
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ABC News​


As well as the actual causes of the flooding, the focus of the inquiry so far has been the response by various government and qango agencies, including but not limited to:

  • deployment of major search and rescue resources, especially helicopters (there are seven different state and federal government agencies who can task helicopters),

  • the response to the emergency by the Police (the commission has heard how Toowoomba's call centre overloaded during the flash flood in that city),

  • the rôle of the State Emergency Service (SES), and

  • the management of Wivenhoe Dam (the major flood mitigation resource for the Brisbane River).

This is only the first round of the inquiry. After seven weeks of hearings it has received hundreds of submissions and has more than 6 million pages of material to process and analyse. An interim report is due on August 1 this year.

Round two will consider land use planning and the performance of private insurance companies.
 
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