No what?
The last flood was mismanagement of Wivenhoe spill. But as hydrologists pointed out it, would have been even more epic if development hadn't increased the flood plain.
I'm not debating climate change, just offering an observation. The last one cost me tens of thousands of money so I'm rather interested in Wivenhoe and it's function.
You might be interested in this:
http://www.qhatlas.com.au/brisbane-floods-1893-summer-sorrow
The ‘history books’, however, may also tell a different story of history repeating itself in tragic and predictable fashion. Questionable planning decisions, dubious waterfront development and the alleged parsimony of the insurance industry were all upshots of the disaster. While reducing the flood by approximately forty percent, many were shocked that Wivenhoe could not stop the flood water. Following the dam operation manual, the necessity to release water to ensure integrity of the dam wall caused downstream flooding.
The flood has been termed a “dam release flood” by hydrologists appointed by the Insurance
Council of Australia. This suggests that a release of water from the Wivenhoe Dam was a principal
cause of flooding along the mainstream and tributaries of the Brisbane River downstream of the dam
over the period 11th–12th January 2011. Whilst the dam operators were acting in accordance with the
operations manual for the dam, their modeling did not take account of forecast rainfall in determining
the predicted dam water level, and this resulted in a sub-optimal water release strategy.
Structures: Structures that are placed in a creek or waterway, for example culverts in an urban drainage
system or bridges in a river, reduce the water-carrying capacity of the waterway and may contribute to flooding. Debris can also become entangled on these structures, worsening this process. Levees along a waterway are designed to protect areas behind the levee from floods up to a certain level, but their constraining influence on flood flows can cause upstream flood levels to be higher than they otherwise would be. Road and railway embankments, with insufficient cross-drainage capacity (for example, use of culverts), can block off parts of the floodplain with a similar effect. Once levees or embankments are overtopped or breached, the way floodwaters spread over a floodplain can alter significantly and the impact of flooding is often severe.
Development increased the flood plain?
http://www.qhatlas.com.au/brisbane-floods-1893-summer-sorrow
https://riskfrontiers.com/pdf/water-03-01149.pdf
http://www.chiefscientist.qld.gov.a...s/floods/understanding-floods_full_colour.pdf
The "Development" hardly contributed to the flood plain but actually made the flooding worse as the man made levees to protect the urbanisation increased the height of the water.
That is what I meant by "NO"
Anyhoow, when the country was covered in forests heavy downpours were cushioned, cradled and to some degree absorbed more.
Stop all logging and plant more trees.
Anyhoow, when the country was covered in forests heavy downpours were cushioned, cradled and to some degree absorbed more.
Stop all logging and plant more trees.
Plod, can you explain to me why we have had such good winter rains in central Australia and western Queensland recently causing flooding in many parts....Most unusual weather really.
That is the point, it is UNUSUAL. The natural cycles are being disrupted and replaced by freakish events that are unpredictable.
It's pretty hard to determine what is seasonal weather these days, and that stuffs farmers up and a lot of other people too.
That is the point, it is UNUSUAL. The natural cycles are being disrupted and replaced by freakish events that are unpredictable.
It's pretty hard to determine what is seasonal weather these days, and that stuffs farmers up and a lot of other people too.
Creek blockades were a non event because the king tide exceeded the height of the creeks. Deforestation, land levelling, etc mitigated a worse outcome
Seven major flood peaks have been recorded at the Brisbane gauge since records began in 1841. A major flood peak of 4.46 metres (6th highest) was recorded at 3:00am on Thursday the 13th of January 2011. This is the largest flood peak recorded since the January 1974 flood when the Brisbane River reached 5.45 metres. Higher levels are possible in Brisbane with two floods (8.35 metres and 8.09 metres) being recorded two weeks apart in February 1893 and higher still in the record flood of January 1841 at 8.43 metres.
The last flood in Brissy followed a relentless rain that went on month after month. As you may well know, Brisbane rains aren't like winter rains found in the southern states, they tend to bucket down. Every inch of the place was sodden and land locked by the various hill barriers that surround brisbane.
It's hard to describe the massive water flow that the dam's release caused as it also syphoned ground water into its tide. Down at Gailes, for instance, the river bank is a yawning chasm normally, but it filled and overflowed another 5 metres above with the torrent. I watched my factory become inundated with 4 metres of water in an industrial estate in a matter of a couple of hours....fortunately recent major roads works opened a relief path to a wider flood plain. The gentrification of riverside suburbs had seen the old factories disappear and large scale drainage installed, etc
Unless you live it, you can't understand it.
SHEEESHHH !!!!!! Nothing to do with Cyclone Tasha meeting up with an El Nina trough and the FACT that the operators of the Wivenhoe dam did not release water prior to the heavy rainfall or the FACT that they had excess water in the dam so that Brisbanites could use sprinklers during the summer months.
So the damage was severe due to the expansion of the population of the Brisbane and surrounding regions. In 1893 the Brisbane River peaked at 8.93 metres. 2011 was 4.46 metres. Was it CLIMATE CHANGE that caused that amount of rain to fall in the catchment areas 123 years ago??
Really mate? I mean really!! You are picking a fight with someone who went through the trauma and you want to points score?
Have a scour for the National Geo article that clearly points out how the dam was built to overflow, etc. Throwing up hindsight is for useless t1ts.
Just move on and suck it up cobber.
Where are you reading that the Chief Scientist of Queensland said that development DID contribute to the flooding? Must admit, bit confused where he comes into this.Try reading the 5 or so links I have provided (or is the Chief Scientist of QLD wrong?) when you want some FACTS rather than a National Geo article or some flippant commentary from yourself.
Structures: Structures that are placed in a creek or waterway, for example culverts in an urban drainage
system or bridges in a river, reduce the water-carrying capacity of the waterway and may contribute to flooding. Debris can also become entangled on these structures, worsening this process. Levees along a waterway are designed to protect areas behind the levee from floods up to a certain level, but their constraining influence on flood flows can cause upstream flood levels to be higher than they otherwise would be. Road and railway embankments, with insufficient cross-drainage capacity (for example, use of culverts), can block off parts of the floodplain with a similar effect. Once levees or embankments are overtopped or breached, the way floodwaters spread over a floodplain can alter significantly and the impact of flooding is often severe.
Our report does not examine the specific events of the recent Queensland floods, but rather focuses on
a number of critical, underlying questions relevant to floods generally.
Where are you reading that the Chief Scientist of Queensland said that development DID contribute to the flooding? Must admit, bit confused where he comes into this.
I'm not saying the development did not and it's definitely possible it did, but the link your provided from the Chief Scientist doesn't confirm it DID (ie. it's not shown as a fact out of his mouth like you're making out).
Here's what you quoted:
(my bolds)
http://www.chiefscientist.qld.gov.au...ull_colour.pdf
No where does he say they DID in the Brisbane event in January 2011.
In fact, the very front of the report says this:
Maybe I missed it, but which of your links has the chief Scientist of Queensland stating development contributed to the flooding as a fact?
EDIT: It's possible I'm just misunderstanding what you guys are actually arguing about.
Thanks trainspotter that clarifies what you were trying to say for me. I think the point you were trying to make got lost (at least for me) in the back/forth nature of your conversation with Tisme (which obviously happens in most discussions on the internet as they go from a broad issue to splitting hairs over something within that broader issue).
I don't really have any answers for you about 1893. It's probably hard to infer much at all in regards to climate change from any of these extraordinary events.
Really mate? I mean really!! You are picking a fight with someone who went through the trauma and you want to points score?
Have a scour for the National Geo article that clearly points out how the dam was built to overflow, etc. Throwing up hindsight is for useless t1ts.
Just move on and suck it up cobber.
"(Edited 12/3/2011. New modelling has shown the the height of the 2011 flood without dams would have been seven meters at the port office. On that basis, it would have been the fourth largest of the historical floods. Based on flood volume, it is the third largest at 14000 cumecs ignoring the effects of Wivenhoe and Sommerset. That places it behind 1893 at 14600 cumecs, 1841 at 14100 cumecs, but ahead of 1974, which would have reached 10,360 cumecs where it not for Sommerset.)"
http://bybrisbanewaters.blogspot.com...brisbanes.html
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