Australian Politics Forum - Brisbane flood level predictions

freediver

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Brisbane flood level predictions
Jan 11^th, 2011 at 5:21pm

General flood maps for prospective home buyers:

http://www.brisbane.qld.gov.au/

The problem with these is that it doesn't say what river level it corresponds to. Blue is for the river rising, yellow is for localised flooding.

A map of the 1974 flood levels, as well as predictions of inundation for various flood levels at the Brisbane post (port?) office. The water is predicted to (just?) exceed the 1974 level on Wednesday evening, then rise further on Thursday.

http://lexiphanic.com/floodmaps/1974_Flood_map.pdf

BOM flood warnings:

http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDQ20805.html

[currently predicting 14.2m at Jindalee (Western Freeway) bridge Wednesday evening, then further rises]

Compare this iwth the 1974 levels:

http://www.bom.gov.au/hydro/flood/qld/brochures/brisbane_lower/brisbane_lower.shtml

which was 14.1m at Jindalle bridge. This one also shows previous flood events - there were 3 in the 1800s that significantly exceeded 1974.

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JC Denton Gold Member Offline Posts: 5197 Gender:	Re: Brisbane flood level predictions Reply #1 - Jan 11^th, 2011 at 5:22pm Did Global Warming cause the ones in the 1800s?
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freediver Gold Member Offline www.ozpolitic.com Posts: 47481 At my desk.	Re: Brisbane flood level predictions Reply #2 - Jan 11^th, 2011 at 5:24pm Would you mind leaving this thread for serious technical questions, at least until the flood is over? There is genuine confusion about predicted levels in Brisbane and people need to plan.
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qikvtec Gold Member Offline Australian Politics Posts: 1846 Queensland	Re: Brisbane flood level predictions Reply #3 - Jan 11^th, 2011 at 5:27pm FD as I understand it they are Q100 maps, so you could expect this flooding to go close, perhaps be the same, or be somewhat over. My suggestion would be that if you lived within a couple streets of the flooded area to ensure you have a couple metres of elevation above the zone or move to higher ground.
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codswal

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Re: Brisbane flood level predictions
Reply #4 - Jan 11^th, 2011 at 5:41pm

qikvtec wrote on Jan 11^th, 2011 at 5:27pm:

FD as I understand it they are Q100 maps, so you could expect this flooding to go close, perhaps be the same, or be somewhat over.

My suggestion would be that if you lived within a couple streets of the flooded area to ensure you have a couple metres of elevation above the zone or move to higher ground.

do you think everyone will move to higher ground.. and would they be allowed too??..I would imagine with houses gone their land has gone as well.. roads are gone trees are gone..somewhere there will have to be a huge rethink...I wouldnt know where to begin. I hope they are already working on getting the cleanup/repairs coordinated..

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perceptions_now

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Re: Brisbane flood level predictions
Reply #5 - Jan 11^th, 2011 at 5:48pm

Wivenhoe put to the ultimate test

Brisbane's main defence from a catastrophic flood is facing an unprecedented test as heavy rain continues to inundate southern Queensland.

The Brisbane River has already broken its banks in part of the city and evacuations are underway in some suburbs.

Further upstream the Wivenhoe Dam, built in the wake of the deadly 1974 floods, is pumping record amounts of water over its spillway as the flood situation rapidly changes.

Last night releases from Wivenhoe's five gates were at about 236,000 megalitres, but that level will be increased today.

Wivenhoe Dam is already at 173 per cent and levels are rising. Its maximum capacity is 225 per cent.

Professor Hubert Chanson, a professor in hydraulic engineering at the University of Queensland, says the dam was built to withstand an event similar to what we are seeing.

But he says the unprecedented rainfalls southern Queensland has seen, combined with yesterday's 'inland tsunami' which swept through the Lockyer Valley, have pushed catchments to the limit.

"I believe we are in an unusual situation where in Brisbane and Ipswich we might have some flooding that is linked with run-off in other parts of the catchment.

"In other words we have had a very unusual and deadly event."

"If the Wivenhoe become full up to the stage where the water in the reservoir is very close to the crest of the dam, it would mean a situation where the operators of the dam would have to open fully the gate of the spillway," he said.

"Anything coming into the reservoir would have to be immediately discharged."

He says it would be catastrophic if water made it over the top of the dam wall.

"The Wivenhoe Dam is not designed to be overtopped, it is what we call an embankment dam. And if water was to flow over the top of the crest of the dam, there would be a very high risk of erosion of the dam wall and ultimately failure of the dam," he said.

"If the water was to spill over the top of the crest of the dam we would look at the failure of the dam on the possible complete emptying of the reservoir into the Brisbane River with deadly consequences for the people living downstream."

The Bureau of Meteorology says major flood levels in Brisbane are likely to be reached on Wednesday afternoon.

Link -
http://www.weatherzone.com.au/news/wivenhoe-put-to-the-ultimate-test/15872
===================
This has the potential to get very nasty!

Hopefully, the monsoon lows & cyclones will hold off for a while?

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qikvtec

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Re: Brisbane flood level predictions
Reply #6 - Jan 11^th, 2011 at 5:51pm

codswal wrote on Jan 11^th, 2011 at 5:41pm:

qikvtec wrote on Jan 11^th, 2011 at 5:27pm:

FD as I understand it they are Q100 maps, so you could expect this flooding to go close, perhaps be the same, or be somewhat over.

My suggestion would be that if you lived within a couple streets of the flooded area to ensure you have a couple metres of elevation above the zone or move to higher ground.

do you think everyone will move to higher ground.. and would they be allowed too??..I would imagine with houses gone their land has gone as well.. roads are gone trees are gone..somewhere there will have to be a huge rethink...I wouldnt know where to begin. I hope they are already working on getting the cleanup/repairs coordinated..

Why would they not be allowed to move to higher ground; if they weren't whoever made that call would be liable for their loss.

You can't build residential (and potentially anything) below a Q100 line in QLD nowadays.

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Politicians and Nappies need to be changed often and for the same reason.

One trouble with political jokes is that they often get elected.

Alan Joyce for PM

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longweekend58 Gold Member Offline Australian Politics Posts: 45675 Gender:	Re: Brisbane flood level predictions Reply #7 - Jan 11^th, 2011 at 6:17pm I just cancelled a (ironically a WATER) short course my company was to run in Brisbane in March. The hotel we we hoping to run it in wne under 5m of water in 1974 and this time is expected to be worse.
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frenchyjen70

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Re: Brisbane flood level predictions
Reply #8 - Jan 12^th, 2011 at 6:51am

Toowomba is 2300 feet above sea level and is flooded. Sure it is on the downside of the Great Dividing Range and I've heard that that is where the water is mainly coming from but what about where the water usually goes. Thats blocked up from the amount of water.

To put this scarey scenario of Toowomba in persepctive:
Toowoomba 2300 feet above sea level and inland.
Melbourne 100 feet
Sydney varies but around 100 feet
Adelaide around 160 feet
Brisbane around 100 feet
Perth around 100 feet
Hobart less than 50 feet
Darwin less than 100 feet
Canberra around 1,600 feet
Central Australia around 1,000 feet

We've been lucky that the tragedy is so low, still frightening but it could have been a lot worse.
Love the way Australia unites and comes to those in need to help out.

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« Last Edit: Jan 12^th, 2011 at 12:22pm by frenchyjen70 »

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Ex Dame Pansi Gold Member Offline Australian Politics Posts: 24168	Re: Brisbane flood level predictions Reply #9 - Jan 12^th, 2011 at 7:37am <<Love the way Australia unites and comes to those in need to help out.>> ....................................................................... Is that just an Aussie thing jen? I'm stuck trying to think of a country that doesn't help its own in times of disaster. It could be just plain old human nature.
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codswal

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Re: Brisbane flood level predictions
Reply #10 - Jan 12^th, 2011 at 8:24am

Ex Dame Pansi wrote on Jan 12^th, 2011 at 7:37am:

<<Love the way Australia unites and comes to those in need to help out.>>
.......................................................................

Is that just an Aussie thing jen? I'm stuck trying to think of a country that doesn't help its own in times of disaster. It could be just plain old human nature.

morning pansi.. I trust its a good one.. or looking to be.

I agree we keep giving ourselves pats on the back as if we are alone..

of course it a human thing.. we are trying to save ourselves at the same time..how bad would it be if we all went about our business as if it didnt matter..I feel pretty helpless to be honest just sitting watching it play out.but if I could fill sandbags I would.

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qikvtec

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Re: Brisbane flood level predictions
Reply #11 - Jan 12^th, 2011 at 9:58am

frenchyjen70 wrote on Jan 12^th, 2011 at 6:51am:

Toowomba is 700 feet above sea level and is flooded. Sure it is on the downside of the Great Dividing Range and I've heard that that is where the water is mainly coming from but what about where the water usually goes. Thats blocked up from the amount of water.

To put this scarey scenario of Toowomba in persepctive:
Toowoomba 700 feet above sea level and inland.
Melbourne 100 feet
Sydney varies but around 100 feet
Adelaide around 160 feet
Brisbane around 100 feet
Perth around 100 feet
Hobart less than 50 feet
Darwin less than 100 feet
Canberra around 1,600 feet
Central Australia around 1,000 feet

We've been lucky that the tragedy is so low, still frightening but it could have been a lot worse.
Love the way Australia unites and comes to those in need to help out.

Toowoomba is 700 meters or +/-2300 feet.

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Politicians and Nappies need to be changed often and for the same reason.

One trouble with political jokes is that they often get elected.

Alan Joyce for PM

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frenchyjen70

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Re: Brisbane flood level predictions
Reply #12 - Jan 12^th, 2011 at 12:19pm

Ex Dame Pansi wrote on Jan 12^th, 2011 at 7:37am:

<<Love the way Australia unites and comes to those in need to help out.>>
.......................................................................

Is that just an Aussie thing jen? I'm stuck trying to think of a country that doesn't help its own in times of disaster. It could be just plain old human nature.

Not much support came at all for when Pakistan was flooded last year

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frenchyjen70 Gold Member Offline Australian Politics Posts: 518	Re: Brisbane flood level predictions Reply #13 - Jan 12^th, 2011 at 12:21pm Thanks qikvtec, typo well thats what im going with
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muso

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Re: Brisbane flood level predictions
Reply #14 - Jan 12^th, 2011 at 2:31pm

frenchyjen70 wrote on Jan 12^th, 2011 at 6:51am:

Toowomba is 700 feet above sea level and is flooded. Sure it is on the downside of the Great Dividing Range and I've heard that that is where the water is mainly coming from but what about where the water usually goes. Thats blocked up from the amount of water.

The problem with Toowoomba is the shape. It's in an extinct volcanic caldera and when it rains heavily, the water rushes down West Creek past the CBD (Just past MacDonalds) where it levels off and accumulates.

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