Topic: NSW Storms then NE NSW / SE QLD Flood Disaster : 5 - 14 January 2011

[Jeff Brislane]

Definately a tragic disaster that has unfolded in SE Qld and my heart goes out to all who got caught in the initial phenominal flash flood and the esuing disaster.

I have heard unsubstantiated reports that the BoM said that 170mm fell in 30 minutes near Toowoomba in what they have called a "super rain storm". Is this true? Has anyone else heard anything like this?

The flash flood event bears a striking resemblance to a lahar which you would normally see caused by the rapid melting of a volcanic ice cap.

Regards Jeff.

[Michael Bath]

Hi Jeff,

This was posted on WZ by a member from Withcott (5ks east of Toowoomba city)

hi guys. Just on my mobile as i have no power and phone line at my home in withcott. Everything fine but withcott is a mess. I spent the day helping cleaning the town up. The water that went down the lockyer was insane. Withcott had 1m of water go through it. The helidon bridge went under by 1.5m! Thats a 20m bridge! Ive heard alot of horrific stories that i wont repeat. The death toll will unfortunately be many more. We received 180.6mm on monday. Most of that fell in less than an hour. We had 430mm for the week and 1100mm in the last 6 weeks.

The Bremer River at Ipswich peaked at 19.4m around 4pm yesterday (about 1m below the 1974 level)

The Brisbane River at the CBD gauge appeared to have peaked at 4.46m 3-4am this morning

[Colin Maitland]

SEQ is an absolute mess, the destruction, devastation and emotional effects are very disturbing. Although the flood caused considerable damage through out many regions, we in Brisbane, in some ways had a slight reprieve by a lower flood height of 4.6 M. This was partly due to very good management and communication between hydrologist controlling the dam and the emergency co-ordinators and everyone else involved.

Thousands were still affected and our hearts go out to them. It does in no way take away the fact that many people have lost every thing and some have lost loved ones. The death toll continues to rise.

To add a little tension there is a low that has developed in the north Coral sea around Willis Island. All eyes will be on this system because some models have this tracking down the coast towards the SE.

Hopefully the members on this forum may be able to put together a summary of events in Qld and NSW shortly to help explain what happened.

Stay safe

Colin

[Richary]

It's been an unbelievable event up there in SEQ, and with the people still missing the news will only get worse. Some incredible pictures I have seen out of Brisbane.

After the initial flood event in Toowoomba I checked out some of the river guages on the BoM site, one guage (which I can't recall and in any case has scrolled off the page) went from 4.5 to 12.5 metres in 55 minutes. You just can't prepare for something like that.

[Michael Bath]

This thread is worth having a look at:

http://forum.weatherzone.com.au/ubbthreads.php/topics/928166/

[Michael Bath]

This event has surpassed 1976 flood levels either side of Great Divide for the northern part of the NSW Northern Tablelands.

The Monday into Tuesday rainfalls in the greater Tenterfield region resulted in:

- the highest flood of the Clarence River at Tabulam since 1976 (not much data for other locations until you get to near Grafton)
- record flooding of the Dumaresq River Bonshaw and downstream.
- major flooding of the Macintyre and Severn rivers (Ashford region) which contribute to the Goondiwindi threat (not sure of any records those areas)
- worst flooding in Tenterfield since 1954

The Dumaresq River at Bonshaw Weir peaked at 8.12 metres Wednesday morning. This is a new record and exceeded the 1976 flood level by 0.25 metres. River levels peaked at Bengalla this morning at 10.95 metres which is above the 1976 flood peak.

We were only at the Bonshaw Weir - Texas area last week while on storm chase and it was already in minor flood prior to this rain.

[Jimmy Deguara]

As everyone has, I have been watching in disbelief with regards to the coverage of the disaster. In particular was the ferocity of the rainfall event and resulting flash flood in Toowoomba, Grantham, Helidon and similar communities. I do sympathise for communities downstream and the hardship they have had to endure in terms of loss of property. However, read some more thoughts in my next post.

Murphy's Creek Flood - Inland Tsunami @ Tiddalac 2011 (Between Toowoomba & Grantham) by Jake

Toowoomba Flood 2011.01.10

toowoomba flash flood

Regards,

Jimmy Deguara

[Jimmy Deguara]

My thoughts on the disaster downstream? This is a major catastrophe - but how much of this could have been avoided?

When I saw footage of the new football stadium and some CBD buildings in water, I shook my head in disbelief. Why? Why have we not learned the lesson of the 1974 floods and planned around it? It seems planners and developers alike allow for building within the flood zone. Countless suburbs were affected by floodwaters - some almost or entirely submerged! Yes I am quite aware of the homes and pubs that have been there for many years but how about the new homes? I wonder how many of these new land owners were 'mislead' into buying property with assurances like - "I have been here for 25 years and it is has never flooded here".

Further to this, these distraught home owners are going to rebuild - how many would have had insurance that covers for such disasters. Who is going to pay for similar massive and avoidable clean up in the future? Surely commonsense legislation should be passed to not allow for a repeat on this scale and restrict development outside flood zones or should I saw within the flood zones. In NSW, my understanding is that planning very much restricts the type of building and development that takes place in flood zones.

It is all about risk assessment and reduction - let's hope commonsense prevails.

Kind regards,

Jimmy Deguara

[Harley Pearman]

I respond further to what Jimmy said in his post above regarding building on flood plains.

I am a town planner and have been in development assessment at Auburn City Council since April 1997. In New South Wales there are zoning controls in Local Environmental Plans (LEP)s which should restrict or even prohibit urban development on flood plains. It is people like me who has responsibility when assessing a developing application for a new building to check flood potential of sites and impact of development on that flood plain. We have a duty of care under Section 79C of the Environmental Planning and Assessment Act 1979 (As amended) to assess this amongst other matters that must be addressed.

In Auburn for example, there are flood zones and as part of the development assessment process, I must look at flooding or have the Council's Drainage and Development Engineer look at the flood risk. There have been instances where I have refused development applications due to flooding. I have had a recent case where a residential development for a granny flat could not proceed due to flooding.

Planners like myself must have duty of care to consider flooding. It is clear that in Brisbane much urban development has occurred on a floodplain which may have contributed to the disaster.

I was reading an article in "The Australian" dated 13/1/2011 titled "Alarming Report on Brisbane River Risk Covered Up" by Hedley Thomas and it is suggested that scientific and engineering experts had forwarned of significant risks of vast destruction of flooding from the Brisbane River as far back as 1999. A Brisbane River Flood Study prepared at the time made alarming findings regarding possible flooding during a significant flood. Engineers and hydrologists involved in the study warned that the next major flood in Brisbane would be 1 and 2 metres higher than anticipated by the Brisbane Town Plan.

The study highlighted how the Council had permitted development of thousands of properties whose owners were led to believe they would be out of harms way in a flood of similar scale to 1974. The study was leaked in June 2003 and it appeared that governments were more interested in property development rather than flood plain management. The calculated 1 in 100 year flood was found to be higher than anticipated.

The report was covered up until it was leaked. Knowledge of the flood risk was known but planning rules did not change (This is a summary of that article dated 13/1/2010).

It does suggest heavy urban development has continued unabated along the flood plain and planning rules did not change despite the flood risks being known.

The operators of Wivenhoe Dam have also come under fire in terms of operations. Should water have been released prior to the event to try and lessen the impact of the flood and to create extra capacity to attenuate the flood?

I am sure there will be lessons to be learnt and inquiries held to find out what happened. I keep seeing in the news bulletins that the damage bill and economic loses will top $13 Billion making it easily Australia's costliest natural disaster to date.

One thing is certain, building a major city on a river with a known history of serious floods is poor planning and unwise.


Harley Pearman

[Richary]

Hi Harley and all

We were discussing this building on a flood plain thing at work on Friday, and someone commented that a lot of the new developments up towards Rouse Hill are also on a 1 in 100 year floodplain. Some are on hills but a lot of that land is flat, and when I used to visit there 25 years ago was paddocks and orchards. Now it's townhouses gone mad. We can only wait until that goes under.

While I realise Sydney is under pressure for more and more housing (something I disagree with but that's another story - can't we decentralise with modern communications) why put the houses there where it will flood eventually. Up towards Dural/Glenorie has huge amounts of land on ridges that will never flood, and is no further from the CBD.

[Simon McCombe]

Hi all. Have been a little quite as have had a few things going on and i try to post a few photos taken from around here soon. Brisbane flood maps if anyone is interested. http://lexiphanic.com/floodmaps/

[Richary]

I saw news reports today that suggested that stormchasers/weather watchers were suggesting the flash flooding for Lockyer Valley about 90 minutes before it hit, while BoM hadn't issued a warning. Hopefully this is something that can be addressed by the enquiry. Should those chasers have phones the bureau, or should the bureau be monitoring those forums? I am assuming it is weatherzone forums though haven't checked.

[Jimmy Deguara]

I cannot believe that we had gone from a drought to the worst floods in living memory in Queensland. It definitely swamps what occurred in other floods - certainly a historic event! Let's hope the recovery process can be quicker than is being depicted although from an infrastructure perspective, it definitely will be years!

Regards,

Jimmy Deguara

[Simon McCombe]

Hi everyone. I know this might seem like past history but i thought i would share these photos here. Received these photos by email the other day showing how quickly the water rose in one part of the Grantham area. These four photos were taken from a farm near Helidon on the 10/01/2011.  This farm is upstream from Grantham which got the full force of this creek,and another creek (Flagstone Creek) which joins into it just before Grantham. There has never been any flood water on this location before. The timestamps on the photos say it all !

[Simon McCombe]

Unfortunately i cant seem to upload these photos at the moment, will do when possible.