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Queensland Floods
- Thread starter Julia
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How does unprecedented growth in coal export cause rain?
Good one burglar. It's amazing how natural disasters bring out the idiots. They are like cane toads, which now have a new lease on life.
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joea,
Just to hand: ASX report from QRN regarding Weather impact on rail services.
http://www.asx.com.au/asxpdf/20110113/pdf/41w55cm8csfqjs.pdf
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Wivenhow Dam certainly helped and saved Brisbane from the deadly flash flooding seen in Toowoomba and the Lockyer valley. A controlled release is much better than uncontrolled and little rain tipped over the next few days meant then the release rate could be cut back significantly. At least Brisbane had some warning of what was coming but a lot of people underestimated how far the water would rise and didnt think of things like no electricity and food shortage.
I like in the Centenary suburbs of Brisbane and luckily i live on a hill. Down the street though, there are heaps of houses that are now cut off from the mainland and without electricity - probably for a few days to come. Tuesday night was bin night in my area so there are heaps of floating rubbish bins and rubbish floating around the streets. Disease will become a problem in the days to come. Most of the main arterial roads are cut off. A lot of people are ready to help out and start the clean up, just waiting for the waters to go down enough to get started.
I like in the Centenary suburbs of Brisbane and luckily i live on a hill. Down the street though, there are heaps of houses that are now cut off from the mainland and without electricity - probably for a few days to come. Tuesday night was bin night in my area so there are heaps of floating rubbish bins and rubbish floating around the streets. Disease will become a problem in the days to come. Most of the main arterial roads are cut off. A lot of people are ready to help out and start the clean up, just waiting for the waters to go down enough to get started.
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I know hindsight is a wonderful thing, but my theory is that the Qld Government, SEQ water engineers and the managers at Wivenhoe tried too hard right from the start to maintain zero flood levels.
If water was being released at greater rates than 150,000 megalitres a day for longer periods we may not have seen 650,000 megalitres being released on Monday night. It would obviously have meant low level flooding sooner for those downstream but it might have meant a much lower peak.
This is certainly not a criticism as the deluge of water that went flowing into the Wivenhoe catchment on Monday was unprecedented and could not be expected.
My point is that people have said the dam has not done what was expected of it (stop another "74 like" flood). My argument is that it was not the dam that failed rather than a miscalculation of the controlled releases, and a presumption that the controlled releases would stop all flooding.
Smurf, maybe you have an idea on this theory? I might be completely wrong.
This brings out the worst in people. In my town here the police were caled in after fights broke out over the remaining loaves of bread at Woolies. Another lady after being told she could only take two loaves, promptly threw the third and fourth loaves on the floor and stood on them. Just crazy, irrational and unsociable behaviour.
Duckman
If water was being released at greater rates than 150,000 megalitres a day for longer periods we may not have seen 650,000 megalitres being released on Monday night. It would obviously have meant low level flooding sooner for those downstream but it might have meant a much lower peak.
This is certainly not a criticism as the deluge of water that went flowing into the Wivenhoe catchment on Monday was unprecedented and could not be expected.
My point is that people have said the dam has not done what was expected of it (stop another "74 like" flood). My argument is that it was not the dam that failed rather than a miscalculation of the controlled releases, and a presumption that the controlled releases would stop all flooding.
Smurf, maybe you have an idea on this theory? I might be completely wrong.
This brings out the worst in people. In my town here the police were caled in after fights broke out over the remaining loaves of bread at Woolies. Another lady after being told she could only take two loaves, promptly threw the third and fourth loaves on the floor and stood on them. Just crazy, irrational and unsociable behaviour.
Duckman
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It's a bit of a case of "damned if you don't, damned if you do". If they had released the additional water and flooded some low lying areas and no additional rains came there would have been hell to pay. It would have been whipped up in a media sensation of houses necessarily flooded. Heads would have been demanded.
They will be reviewing their hydro models and strategies following this. It sure was a good test for the dam and it came though with flying colours and most likely covered quite a bit of its construction cost in this mitigation alone.
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Without the Dam, this would have been a 1890's style disaster. I would love to see those Hydrology experts (or whatever they are called) do a study on what the river levels would have been this week without Wivenhoe. We could have seen 1890's style data like 30metres in Ipswich, and 8 metres in Brisbane (IMO).
Anyway, that is the past. I am in Ipswich CBD today and the clean up is already in full swing. They have council employees everywhere cleaning up the streets. People all over the place cleaning out their shops and businesses. The spirit is just amazing. I was helping this guy pull his stock out of his shop, and it is just a write off, but he is still so upbeat. Incredible.
My biggest concern now is the chance of a repeat in the next few months. With Wivenhoe and the entire SE Qld area being so drenched already, and with the predictions of rain that are being forecast for January through to April, I am really concerned that this clean up will be needed again within the next few months.
That's just my opinion anyway.
Anyway, that is the past. I am in Ipswich CBD today and the clean up is already in full swing. They have council employees everywhere cleaning up the streets. People all over the place cleaning out their shops and businesses. The spirit is just amazing. I was helping this guy pull his stock out of his shop, and it is just a write off, but he is still so upbeat. Incredible.
My biggest concern now is the chance of a repeat in the next few months. With Wivenhoe and the entire SE Qld area being so drenched already, and with the predictions of rain that are being forecast for January through to April, I am really concerned that this clean up will be needed again within the next few months.
That's just my opinion anyway.
Thanks for that. Yeah, I thought it would be all hands on deck.
I am up near Daintree Rainforest. The only problem is the noise from the grass growing.
Cheers
Don't remember exactly how US Folks advised to do it, but roughly it was like this:
- Turn off power supply to tank (gas or electric)
- Turn off intake to hot water tank
- Open relief valve
- Use water as required
(might have to improvise here too, like loosen up some fittings low on tank, push some compressed air through pressure relief valve to force water out)
I suspect that earlier, dam was used to catch water and one could argue that it was good thing to do after 7 or 10 years of drought.
Maybe we should have one dam kept empty for flood event and another one for water supply, as events like that cannot be predicted month in advance.
I think about month (give or take few weeks) would be needed to drop dam water level without causing any floods to be ready for the big water event.
Hope next flood will be met with better resources, because we know it will happen, mater of time!
Garpal Gumnut
Ross Island Hotel
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Whiskers
It's a small world
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Well, I figure I just had a 'natural' instinct to survey the possibilities and what could be reasonably achieved with what there is. My thanks go to the likes of you and Smurf who are able to provide sound data to make some judjements from.
I don't dissagree with that drsmith. My query was whether they got all their sums right to accomodate a worst case scenerio. Btw, do you live in the higher flood levels?
How do you know it's God that's angry and not the Devil trying to ruin Gods kingdom?'Çoud not be expected' is probably a bit unrealistic. I'd agree given the Flood Mitigation hype, most people just considered that it would not affect Brisbane, but I'm sure the Wivenhoe planners anticipated some degree of extreme and unprecedented event in their design. That's the numbers I'm curious about.
Yeah, I agree there to a large extent. I note that they did get some criticism a few weeks ago for releasing a bit too much and causing minor street flooding in Bris. That's my concern with building such mega-dams, ie you then have to get a pretty good handle on managing the flows as well as anticipating future inflows.
While the reports say Wivenhoe reached 192ish% I note they haven't updated the chart from the day before (11th) when it was at 160%. I got the feeling that they were more than a little concerned being in untested territory.
The biggest issue with earth fill dams is drying of the clay core in drought and then filling too fast and water leaking through the cracks in the clay and causing a failure of the wall. Must have been on the minds of the managers and engineers as it rapidly rose to the upper levels that have never seen water before and I suspect they would want to lower the levels soon to take the pressure off while the clay core stabalises.
Fortunately, I didn't notice or hear of any bad behaviour like that in Bundaberg. I see yesterday that grocery shelves are largely empty waiting for supplies to get past the flooded highway at Gympie.
I did hear though that as far as Bundaberg and maybe Maryborough are concerned that fuel supplies are beind sourced from Gladstone in the interim.
Yes, if there was complacency before, people should be asking questions and making better plans for the rest of the wet season.
Attachments
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With the ongoing evolution seasonal rainfall forecasts, it may become viable to dip in to the storage component of Wivenhoe to increase flood mitigation capacity without too much risk to normal water supply.I don't dissagree with that drsmith. My query was whether they got all their sums right to accomodate a worst case scenerio. Btw, do you live in the higher flood levels?
The current La-Nina and resultant higher probability of higher rainfall is a good example. Easy call to make now, but may have been brave even 3 months ago bearing in mind a long recent history of drought and the inherent unreliability of seasonal rainfall forecasts for point locations or small areas.
I live on top of the escarpment to the east of Perth. It'll never flood, but it could burn.
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The government should have dug out the Wivenhoe Dam deeper when hey had the chance. That's what all the farmers do when there's a drought.
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http://www.bom.gov.au/hydro/flood/qld/fld_reports/brisbane_jan1974.pdf
Historical flood information on pages 13 to 15.
In Februrary 1893, there were two floods over 9m, 9 days apart. No wonder they're keen to quickly restore the flood mitigation capacity of Wivenhoe
Historical flood information on pages 13 to 15.
In Februrary 1893, there were two floods over 9m, 9 days apart. No wonder they're keen to quickly restore the flood mitigation capacity of Wivenhoe
Whiskers
It's a small world
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Me too... but I have my spraying and extra fire fighting equipment at the ready, I'm prepared.
Oooh gees Market Depth... that would have been a waste of money.
I have built dams on my own property (up to 6 meter wall height) and the principle is to remove material from the hole to make the wall, but generally we are looking to hold back considerably more times the volume of water than clay, rock and soil we dig up, say at least 10:1 often 20 or 30:1 and more. The greater the ratio the better. 1:1 is thoroughly uneconomical for water catchment.
9 meters is a hell of a flood.
I wonder if this was their benchmark that they modeled to.
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Fair point. But you could hardly call the bligh government 'Thrifty' to start with. They spent a mountain of cash on trying to get the Traverston dam off the ground, that just turned into a 'Money Pit'. As too has the Queensland Health payroll sucked up it's fair share of wasted cash. Not to mention others. They could have raised the Dam wall for less money, but property owners wouldn't be happy with that. I guess the government is betting on the costs of damage to flooded properties to be less than taking action before. As with most things these days the private sector will be left holding the 'BAG' sadly.
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It comes down to probability in a manner very similar to share trading using a back tested system. Run the simulations and operate in a manner that produces the best overall result without any major disasters along the way.
In hindsight there's a "right" answer, but at the time it really does come down to probability and the best available weather forecasts. Like most things, you can only act on the information available at the time.
This stuff is done routinely under non-emergency conditions too. Rain should be coming, so dams with a large catchment relative to storage capacity are drawn down with the objective of minimising spill (noting that in this case the objective is to capture as much water as possible rather than stopping a flood).
As an example, here's what's being done in Tas at the moment, noting that some parts of Tas are also now flooded (though nowhere near as bad as in Queensland). http://www.hydro.com.au/about-us/ne...xpected-heavy-rains-over-north-and-north-east
WaveSurfer
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Deepest sympathies to all of those affected by the floods. Hope you're okay up there in Bundy Julia.
I donated 5k to the cause. Here's hoping it gets to those who really need it.
You ain't gonna prevent this in future, no matter what half-arsed attempts are made. Mother Nature always lets us know who's boss. Bit like the markets actually.
I donated 5k to the cause. Here's hoping it gets to those who really need it.
You ain't gonna prevent this in future, no matter what half-arsed attempts are made. Mother Nature always lets us know who's boss. Bit like the markets actually.