WITH respect to what has happened in this major flood disaster in Brisbane, the role played by the huge Wivenhoe Dam in this flood will be called into question, and as the cleanup is starting now, many more questions will be asked in the wash up, if you’ll excuse the lame pun, and a lot of those questions will have political ramifications.
There is absolutely no doubt whatsoever that this monster dam played an absolutely crucial role in preventing what could have been an even worse disaster. I have mentioned earlier that this huge dam held back water that would have made this flood something not worth even contemplating.
Water was flowing into Wivenhoe at a greater rate than could be released with all five spillway gates open at their maximum. At one stage, water was pouring down those spillways at a rate of around 650,000 megalitres per day, and that is what caused the initial flood devastation in Brisbane. Had they not released that water at that rate, there was the very real probability that the flood would have been even more devastating, only a few days later, perhaps right in the middle of those King tides.
That initial huge release was due to the fact that releases of water from an already filled Somerset Dam, (directly upstream, and itself at 175% capacity and rising, and also filling faster than it too could release, and with all its flood mitigation compartments full) were rapidly filling those flood mitigation compartments in Wivenhoe itself.
Wivenhoe was also filling from runoff in its own catchment as well as what it was receiving from Somerset, and at one stage water was flowing into Wivenhoe at a greater rate than what they were releasing at that maximum I mentioned above.
That initial outflow was eased back after 24 hours, and that initial huge release is what caused the flood damage in Brisbane. The release was eased back to a rate of around 215,000 megalitres a day and stayed at that rate for 2 days.
Now that the major flood peak has passed in Brisbane with the advent of the two king tides, that release from Wivenhoe has increased again to around 320,000 megalitres a day. With the river in Brisbane dropping from its major peak, that release will keep the river (relatively) high, but at a controlled level.
Those current releases from Wivenhoe just have to be kept at that level so they can empty the flood mitigation compartments of this monster dam, now sitting at a level around 192% of capacity. Those releases will continue for days until those flood mitigation compartments are empty.
The reason for this is that if there is another major rain event, and there have been some forecasts for a Cyclone that could move back towards the Coast around the Brisbane to NSW border area late next week, then those compartments will have room in them to actually fill again.
If all that water from that earlier rain event of such huge proportions was kept in Wivenhoe, then any subsequent rain event will see Wivenhoe, already topped out at its maximum holding of around 225% totally full, and then Wivenhoe, and its engineers already performing a huge juggling act will have nothing left to do but let monumentally huge amounts of water flow down the river and into Brisbane, causing an unspeakable tragedy of a far greater proportion than it has already caused now, something that is not worth even contemplating.
UPDATE 18TH JANUARY
Now that the inquiry has been called, I suspect that, (and please don’t think of me as a conspiracy theorist) some aspects of that SEQWater website might be removed from public access.
What I am referring to here is not the home page information, or even the dam levels page, but a small part of that latter page that not many people might even refer to.
http://seqwater.com.au/public/dam-levels
If you visit that Dam level page, at the bottom, you’ll see a small interactive chart detailing the current water levels across the whole storage. If you go there, you can navigate around, so there’s no real need for me to explain how to use it.
The default setting shows the tick in the right column set to grid three, but you can add individual dam levels so that the level for that dam overlays the main image of total level.
Tick the square alongside Wivenhoe, and the level for that dam appears on the chart.
Now, untick the default Grid three so only the Wivenhoe level shows there.
Now, scroll your mouse slowly along the line and the levels for each day show up as a percentage.
Get close to where the upwards spike starts and carefully roll the mouse up the spike.
At the bottom is the level for Friday at 106.3%.
No entries for Saturday and Sunday as has always been the case, and I can understand that it’s the weekend and the person tasked with updating the website is away, naturally.
The next reading is for Monday at 148.4%
Then Tuesday 11 Jan (9AM) it is at 175.9%
Wednesday (9AM) it is at 188.5%
Thursday (9AM) it is at 186.5%
Friday (9AM) it is at 179%
Then nothing more until Monday and Tuesday, (today) as levels spike back downwards as those flood mitigation compartments are emptied back out.
The huge rain event in the catchment started Monday PM, and went until Tuesday PM, and I watched it on and off for most of the day on the BOM Mt Stapylton map set to 128Km.
Look at the levels from Friday until Monday, and it rose steeply, and on Tuesday AM was close to its maximum.
The releases obviously started on the Monday, accelerated on the Tuesday to that 645,000 ML rate, and the peak in Brisbane arrived 36 hours later and was then added to by the high tide.
However, it would ‘seem’ (term used very carefully here) that from Friday to Monday, not very much was released, until the levels had become alarmingly high.
For more information:
Link to article on Fed Govt releasing flood maps:
http://www.couriermail.com.au/news/features/maps-show-southeast-queensland-climate-change-flooding/story-e6freowx-1225971661224
Link to flood maps. This is local SEQ, and above that there are maps for all major cities in Australia. The maps take you to further maps and you can click on individual areas and get three scanarios for each area. (pdf document maps)
http://www.ozcoasts.org.au/climate/Map_images/SthEastQld/mapLevel2.jsp
****************
Tony is a Rockhampton-based blogger who mostly writes for a US-based audience.
To read more from Tony you can find links to main posts and updates here: http://papundits.wordpress.com/2011/01/13/brisbane-and-queensland-flood-crisis-with-updates/
Learn more about Tony here:
http://papundits.wordpress.com/views-expressed-by-writers-are-their-own-and-do-not/tonyfromoz/
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
“The reason for this is that if there is another major rain event, and there have been some forecasts for a Cyclone that could move back towards the Coast around the Brisbane to NSW border area late next week, then those compartments will have room in them to actually fill again”
Have you got a source for that? Channel 9 had this on the news a few days ago, but I can’t find anything at BOM.
Just found this pic of the 1841 flood.
http://i446.photobucket.com/albums/qq187/bobclive/Brisbane1842.jpg
Tony,
A timely critique. The bureaucrats obviously took the weekend off and forgot about the problem until it was too late. A major blunder occurred here.
eg,
I very much doubt that is Bris ’41. More like Bris ’93.
In 1841, before statehood and the gold rush, Brisbane was not much more than canvas town.
[but much more capable of coping with floods]
SD,can you post some evidence before flippantly claiming the ‘bureaucrats took the weekend off’?
Are you basing this idea on the fact that the SEQwater website didn’t update dam levels daily?
Definitely not 1841,El G…wrong hats,wrong architecture,and Gordon and Gotch didn’t exist before the late 1850s.
Spangled – really crappy nasty comment – engineers have been hard at work since before Xmas non-stop on 4 river systems going off at once. Do you think they have no idea of the issues at Wivenhoe – dam safety, downstream flooding of houses and property, tides, weather forecast. What a juggling act. Calls have to made and ain’t 20:20 hindsight wonderful. Imagine if you got caught with a 1974 like cyclone Wanda bearing down and Wivenhoe at 190%.
Sheesh mate !
There’s some good discussion here by locals about Wivenhoe monitoring. A “Campbell Newman” obviously wasn’t in charge.
http://joannenova.com.au/2011/01/brisbane%e2%80%99s-man-made-flood-peak/
Luke,
There are many facets to this but I can’t help thinking we had a “Christine Nixon” moment with Wivenhoe. Someone took their eye off the ball at the crucial time.
Thanx spangles and poly for the clarity on that pic.
Luke I’ve answered your last comment to me on past thread, so what do you think?
I’ve used the la nina years from the REAL rainfall record and you’ve still got no case, except your reliance on one year and of course your religious faith.
Pity about the facts though,but please no more BS or infantile abuse, you’re just wrong.
Armchair critics – after the event ! The olde adapative response bitching in hindsight – where was the warning blog post. Plan B you know ….
Wivenhoe was lowered pretty quickly to close to 100% on the 4th January after the smaller floods at the end of December took the dam up to about 123%. I think they shed about 250GL in six days to get back to operating requirements.That’s a lot of water,and during some of that time the release caused minor flooding downstream,which also had freshs from the Lockyer and Bremer.
At this stage,they had air space of 1400GL to cope with future flooding.Sounds good enough,was entirely by-the-book,but they did not know just how intense the next rains would be.
The percentages used on the website are of the1165 GL full level,so one percent is 11.65 GL. This gives an idea of the astonishing volume of increase over the weekend; over 41%/c. 480GL in 72 hours to 8 am on Monday 10th January. Then the next 24hrs saw 320GL added to the flood reserve. The next 24hrs saw another 12.6% or 147GL,despite increasing releases. Suddenly the great air space was just about gone.,and SEQwater’s hand was forced with no sign that the trough was going to shift.
Looking back in rose-coloured hindsight,if they had continued the big releases for the three days from the 4th,and taken 5% a day out,they could have had 175GL more space…or if they had dropped it 8% a day they could have won 280GL. But releasing 90GL/day all day produces quite a bit of flooding downstream,cuts all the lower bridges and backs up the Bremer. However,if they had got the dam down to say 85% before the inflows,no doubt the Brisbane peak would have been a bit lower,but that also depended on the same circumstances we saw: the trough breaking up,the rain suddenly stopping when it did. The flood would still have been bigger than 1996,and probably at or near major level at the City Gauge.
We knew there was rain coming,but none of us knew how intense the falls would be,so it’s a bit unreasonable to accuse the release managers of negligence. It’s no simple matter to draw up the release manual,there are a lot of downstream factors to consider.
Poly, yes there are many combinations of possibilities and you probably can’t write a manual for them all but compared with chaotic weather possibilities that are reasonably well predicted for several days ahead, one would think that this sort of rare, reasonably straight forward event would be catered for to the max with today’s technology.
Not to mention OHS philosophy.
You’re going to hear a lot about that release figure of 645,000 ML from Wivenhoe in the coming day and weeks.
However, people are looking at this from the wrong direction.
They will say that this is what caused the flood, and true, it did.
However, that release was due to the fact that the water flowing into Wivenhoe was at a greater rate than they could release it at that 645,000 mark.
Had they kept it behind the wall and not released it, the flood would have been immeasurably worse, only days later.
Also true is the fact that the Dam levels page was not updated on the 12th and the 13th, only showing levels as at the 11th.
However the home page was updated indicating that release of 645,000. You won’t see that page again, as even though I linked to it here earlier in one of my comments, that page is updated daily, so if you take that link now, you will only see today’s updated home page:
http://seqwater.com.au/public/home
That 645,000 release was for one day only, and then it lowered to 215,000 for two days, and it is now back up to 301,000 so that they can empty the flood mitigation compartments, as they are required to do, in readiness for any subsequent rain event.
Wivenhoe fills doubly fast, because all of Somerset flows into it, as well as what it receives from its own catchment.
This was an absolutely incredible juggling act on the part of the engineers, and no amount of ‘dropped the ball’ comments (sorry) can detract from the fact that had they not done that, it would have been so much worse.
However, all the talk will only be centred on that 645,000 mark, and people will point fingers at that and say ‘culprit’, and that will be totally incorrect without context.
I have heard some talk of catastrophic failure, huge releases from the automatically operated relief gates, and all of this, had they kept back that water would have seen catastrophe on a scale not even imaginable.
Now, as to the Cylone.
I saw a report from Garry Youngberry on Channel 9. He’s ex NBN, and ex weather channel, and probably one of the better TV weather ‘talking heads’.
He mentioned the cyclone forming in the North, (which it did) being sucked out to the east by the even bigger cyclone out there, (which it is) and then rolling south, and then back west to come to an area between the Gold Coast and the border around the 27th/28th January.
That one report was repeated later that same day, and then pfft. gone.
I’ll bet he was told to shut up pdq.
His report was detailed, and he mentioned that in fact, we could be lucky, if a cyclone coming can be called lucky, as the vast bulk of rainfall attached to cyclones falls to the South west of them, which is well South of the Somerset Wivenhoe catchment area.
Again, I apologise for taking so much space here.
Tony.
Sadly, ‘bitching in hindsight’ is essential for future planning.
If you’ll all forgive me for a tiny little wry comment, if they can’t predict an event like this at a day’s notice, how can we believe they can predict what will happen many years into the future.
I know, I know, weather and climate ….. same old same old!
Tony.
SD,I think they do try and write a lot of possibilities into the manual,and while I agree the event was ‘rare’,it certainly was not ‘straight-forward’.
All the gauging stations on the above-Wivenhoe streams were jumping up and down hugely, Lockyer and the Bremer were having multiple peaks in the preceding ten days ,too,and towards the end of the event,the heavy rain set in between Wivenhoe itself and Brisbane,so local creeks were all coming up and backing up against the swollen river.
Much as one would like to,one can’t suddenly dump water out of the dam. Lots of warnings have to be sent out,received and re-sent to get everyone up to speed in very short time frames,and it’s never the right time of day.
Another thing that I find unhelpful is that when SEQwater use the ML/day figure for describing releases it gets confusing. When they said they had increased outflows to 645,000ML/day of course this wasn’t literally to be for a whole 24hrs,but just for some tens of minutes or maybe an hour. They should really use a measure that describes transient flow and change better,like cumecs. And they should be able to give a running mean total for a six or twelve hour period to give better context of the shape of their actions. Then,at the end of 24hrs they can tot it all up and come to a mean, and this is the less ambiguous way to use the ML/day usage.
If the Coral Sea is as warm as some are claiming then we should have had a cyclone to go with our flood.
However it’s still not too late for that to happen and [playing devil’s advocate to help prevent it from happening] if the CS is warming to that extent and with current SOI etc, we could have a spate of floodings for the next six months.
Repeats of big floods in the same year are what happens in these sits.
When the cyclone struck in ’74 at the height of the flood it breached the spit at the old Marineland theme park [where Sheraton Mirage is now] and cut a second entrance through at Jumpinpin. [the first entrance was cut in the 1893 flood, prior to that Stradbroke was just one island]
“,and while I agree the event was ‘rare’,it certainly was not ‘straight-forward’.”
Poly, In this weather pattern it probably can’t even be described as rare. It should be expected. And as for being not straight forward, it is nowhere near as chaotic and difficult as everyday weather forecasting.
AAPOI, I’ve been trying to contact SEQ Water [no luck so far] to suggest that the Hinze Dam levels be kept as low as possible because of the possibility of flooding in the very near future.
SD,
They’ve emptied 25,000 ML out of Hinze in the last 2 days.
This is the link to the SEQ Dam levels, updated yesterday.
http://seqwater.com.au/public/dam-levels
As you can see there, Hinze is at 100%.
2 Days ago, that level for Hinze was at 186,000 in that second column there. (Current Capacity)
Thank heavens they only recently finished raising the wall to Stage 3, originally proposed in the original design specs.
When Advancetown was first flooded by Hinze Dam in 1976, it was a pity, not for the environmentalist reason, but because there was a small country house cafe there that made the single best ‘Devonshire Teas’ I have ever had.
Tony.
Tony,
Do you know if, with this recent raising of the wall and spillway, whether they have a reserve spillway a la Wivenhoe?
If they haven’t, they’d want to dump a lot of water PDQ.
After reading Lowe’s vomitous piece blaming the floods on AGW I must say that deju vu is in the air with the same rotten connections made during the Black Saturday fires now starting to emerge from the flood detritus. Lowe says this about the dams:
“There is no obvious place to dam the Fitzroy River to protect Rockhampton. The proposed Traveston Crossing dam would have been an ecological disaster and would not have protected Gympie, just as Brisbane was flooded despite the enormous amounts of water stored in the Wivenhoe and Somerset dams”
What leaps out at me is the term “ecological disaster”. Compared to the floods I suppose.
The other issue which luke has belted in his contribution to agnotology is the SST; BoM shows them going through the roof around Australia; I can remember having this same discussion about 2 years ago; Hughes and McLean had some good data then and it is still good now:
http://www.warwickhughes.com/blog/?p=191#more-191
http://mclean.ch/climate/GBR_sea_temperature.htm
Of course globally SST has been trending down since 2002; why should Australia’s coastline be boiling when the rest of the world is not?
Luke and Poly get upset when the boffins’ integrity is questioned; poor dears, I expect they would like it to be as professor Lewandowsky would want: trust me, I’m smarter than you; but I see even Lewandowsky has turned to the jury of public opinion as his latest Unleashed agitprop shows ; obviously the scientists have failed him.
SD,
Hinze Dam was originally designed to have three stages. Lack of political will only saw stage 3 completed late last year 2010. almost 38 years since it was first proposed.
That final stage 3 includes flood mitigation compartments, larger than the amount I mentioned above that has been removed from the Dam in the last 2 days.
Hinze’s catchment is the 4 mountains behind it, Springbrook foremost among them, and that area has (some of) the highest rainfall in the State. It’s all National Park and State Forest area there with many walking tracks etc. Most parks have picnic seating area in booths, and in those booths they have images of some of the sights etc.
One startling image in one of those booths I remember is an old black and white of Purlingbrook Falls, usually just a trickle with more than a hundred metre drop to the floor below.
It shows an impenetrable mist almost three quarters the way up that drop with the water roaring off the top straight out horizontally for around 20 metres before it starts to drop. It all flows into Hinze Dam.
Hinze was (sorta) expected to take a long time, some mentioned years before it reached 100% if ever.
They has a huge dump in the catchment not long after it was officially opened in 1976 and it filled in days to that 100%.
As part of the ‘water security’ for SEQ that was implemented, the first thing they did was to construct a pipeline from Hinze to the other storages to North, because Hinze was such that good storage because of its catchment.
It has always been a safe water supply because of that catchment area.
Stage 3 has flood compartments that will hold an extra 40 to 50% above the maximum.
With respect to the spillway, I think the spillway was relocated from the original stage 1 spillway during stage 3.
Tony.
SD,we seem to have our lines crossed. It was you who described this event as ‘rare,but reasonably straight-forward’. I agreed it was rare…then you shift your position,saying it should not now be regarded as such!.
I disagreed it was straight-forward,and you suggest it was “nowhere near as chaotic and difficult as everyday weather forecasting” ! Think about it,it IS everyday weather forecasting,with infuriatingly tough hydrography chucked in!
There’s an article in The Australian today http://www.theaustralian.com.au/news/opinion/damned-if-they-do-damned-if-they-dont/story-e6frg6zo-1225988018615
(quoting selectively)
Hydrologist Aron Gingis, a Melbourne-based rainfall expert formerly of Monash University, contacted The Weekend Australian to urge a public debate about the dam’s influence on the flood. According to Gingis, the dam’s operators bear a heavy responsibility for their significant contribution to the flooding.
“They had no right prior to the start of the wet season – when the forecasts were all pointing strongly to exceptional rainfall – to keep so much water in the dam,” said Gingis. “I tried to warn them about the coming disaster and to urge them before it was too late . . . to release much more water to give themselves more storage room for a big one.
“When they finally did release, it was because they had received so much inflow this week that they were afraid the whole system would collapse. There is no doubt in my professional opinion that most of the flooding in Brisbane should have been avoided. It is extraordinary to me that people are not asking more questions about this. Brisbane should have been protected by Wivenhoe Dam. Instead, the dam is a large part of the reason the city has flooded.”
…
One of the questions for a public inquiry will be whether maintaining 100 per cent of the capacity for water storage was prudent given the warnings from September 2010.
…
The extreme rain and run-off from the freak event over Toowoomba on Monday did not fall into the catchment for Wivenhoe. But the storm’s intensity, with almost 200mm falling in less than an hour, caused serious alarm among the dam operators because they realised that such a weather system – if it were to form and drench Wivenhoe’s catchment for several hours – would go close to a Probable Maximum Precipitation event, a feared monster that would create more in-flow than the dam could release.
…
Retired engineer Ian Chalmers, a key project supervisor in the construction of Wivenhoe Dam between 1977-85, defended the decisions of the operators in the past week, adding they will do a better job next time.
“These questions are all valid, but put it this way – you would have to have very large balls to [significantly reduce the dam’s volumes in the months after the weather warnings] after 10 years of drought, because if you had got it wrong you would be accused of wasting the water,” Chalmers said.
(end of quote)
I know hindsight is a wonderful thing but considering the warnings coming from forecasters (referred to in the article) it seems from a layman’s point of view that the WOperators were a little conservative
Nice to hear from you again Tony; how’s Rocky going with the cleanup? And did you try my treatment for midge bites – rub a garlic clove on the bites?
Thanks Tony. 40 to 50% hey. That’s good, because stage 3 is three times the vol and twice the area of stage 2 so that means there is at least a damfull [on a stage 2 basis] for mitigation.
When stage 3 was nearing completion I asked when were they relocating the spillway and they said it was staying where it is [I had always understood they were moving it] so now I suspect they just added radial gates to the top a la Wivenhoe. If those gates are 5m high [the amount of increase] the top of those gates would constitute the max mitigation.
You cant get access to the site these days.
Poly,
Sorry about the “rare”. Had a reconsideration and realised that in these weather patterns [as Franks said] floods aren’t rare they’re almost a cert.
But if they can get the weather right for a few days I think it’s reasonable to mitigate floods better.
cohers,
Yes, if the Coral Sea is warming so much why did Cyclone Vince move to the Arafura after a tug-o-war with the low in the Coral Sea? It’s reasonable to assume that the Arafura was warmer. In either sea the cyclones are not very energetic.
The data collection is so bad at Willis Is, we wouldn’t know.
And people like Lowe will never admit that dams are mostly an environmental positive. And that the slight warming that has happened since the end of the LIA seems to be doing as Lindzen theorised, causing less extremes.
SD,yep.I think floods area certainty in such times,too.
And reasonably certain in which catchments,too…not that it’s a shifting suite,mind you;)
But,but,but… the size of the floods is very variable,and the local and point rain rates are,too. So that gets us back to forecasting,flood management,and the ability to mitigate,which is what some people want to bag SEQwater about. They did actually free up the flood reserve,but the dynamics of this flood prove it needs to be bigger,because they do not want to move people out of the flood plain.
Vals’ quote from water engineer Ian Chalmers is important.
We need that raising of Wivenhoe,and I reckon the 4m option,not the 2.
Val,
thanks for the comment, and especially thanks for your many earlier comments linking to those Posts from Rockhampton.
Here in Rocky the clean up is proceeding. Unlike Brisbane where the water is dropping rapidly, here in Rocky the level is still at major flood levels with the gauge still at 8.25 Metres, and with vast volumes of water still streaming past the City. Major areas of Depot Hill are still under.
They opened the highway to the south at the Yeppen flood plain yesterday and the rigs are streaming into the city, all loaded to the ‘gunwales’.
The airport is still closed, as is the rail link.
The supermarkets are slowly getting back to normal after the second mad panic rush during the Brisbane event.
Er, no, I did not try your garlic recipe for the sandfly bites.
Oddly the best thing that actually did work was that calamine lotion.
Oddly, after toilet paper and baked beans, (well, wouldn’t one lead to the other) the first thing to go in the mornings after the overnight shelf stacking is personal insect repellent. Luckily, milk and bread were sourced locally, but fruit and veg is a little hard to find, unless you get to the door at ‘Sparrers’.
Tony.
“Oddly, after toilet paper and baked beans, (well, wouldn’t one lead to the other)”
Tony, I’ve never felt like baked beans after toilet paper.
Luke,
Some pearls from the lips of our leaders in science.
http://www.smh.com.au/news/environment/this-drought-may-never-break/2008/01/03/1198949986473.html
Cohenite rolls out Hughes and McLean – oh pullease Cohers. Something authoritative.
Gingis eh – not flogging cloud seeding now. Reckoned it was air pollution stopping our rain in capital cities – “a Melbourne-based rainfall expert” – choke !
They’re all coming out of the closet ….
But toilet paper can lead to serious claims of climate change:
http://www.greenprophet.com/2010/12/greenpeace-israel-carmel-fire/
Check here too:
http://hauntingthelibrary.wordpress.com/2011/01/13/environmentalist-starts-israels-worst-ever-fire-greenpeace-blames-global-warming/
Spangles – did I say I was anti-dam – but if you’d like to have lots of infrastructure sitting around without a cost benefit and personally fight all the NIMBY battles in each little glen and dell. Will you be there on the podium Spangles – promoting to the locals.
Wasn’t Barnaby against Traveston? Hey anything for a vote? Just turn around on a dime.
http://www.abc.net.au/news/australia/qld/widebay/200611/s1789151.htm
Tony another link for commenters to consider:
another link http://papundits.wordpress.com/2011/01/15/expert-claims-wivenhoe-was-too-full-to-protect-brisbane/
As the clean-up in Brisbane began, hydrologist Aron Gingis, formerly of Monash University, criticised the policy of keeping Wivenhoe at maximum capacity, not including the dam’s capacity for flood mitigation, in the lead-up to the deluge. He said it meant that the dam’s buffer to absorb a huge inflow of water from extreme rainfall had been severely compromised.
The Queensland government-owned dam’s operator, Seqwater, did not respond to written questions last night.
And Luke is playing the game the Labor Party use – look over there!!!!!
SORRY FOR SHOUTING
THAT’S NO ANSWER; DIDN’T THE LABOR PARTY’S GARRETT DISPOSE OF IT BECAUSE OF ….
Ahead of this week’s flooding, the massive volume of water in Wivenhoe rose to 190 per cent of its notional capacity, meaning nine-tenths of its capacity to absorb flooding had been soaked up.
At 200 per cent, authorities would have been faced with an uncontrolled release of water into the Brisbane River. Mr Gingis said Seqwater had “no right prior to the start of the wet season, when the forecasts were all pointing strongly to exceptional rainfall, to keep so much water in the dam”.”I tried to warn them about the coming disaster and to urge them before it was too late that they had to release much more water to give themselves more storage room for a big one.
“There is no doubt in my professional opinion that most of the flooding in Brisbane should have been avoided.”
Mr Gingis said the dam’s levels should have been taken down much more in the months before the extreme rainfall, and that this would have meant its operators would not have been forced to release huge volumes of water that made a significant contribution to the flood in the Brisbane River.
Ms Bligh confirmed yesterday that dam operators came “very close” to losing control of the massive Wivenhoe Dam at the peak of the flood crisis in Brisbane.
Asked late yesterday if she believed the strategy followed by the dam’s operators in releasing water had been conducted appropriately, the Premier neither endorsed nor commended the strategy, saying it was a question for technical experts to examine.
The IPCC prediction for Queensland was for a drier environment and hardly a word on floods.
http://hauntingthelibrary.wordpress.com/2011/01/06/ipcc-prediction-for-queensland-less-rainfall-longer-droughts-drier-climate/
Wondering how many new dwellings in Brisbane, built since 1974 on the flood plain, are on stilts? Future insurers will demand it.
Luke I should explain myself – all my life I’ve been a swinging voter so the Labor’s Party’s mantra/media spin ‘look over there’ doesn’t impact with me
my response is ‘who’se is Govt now’ and ‘why can’t they make decisions rather than point to the opposition’
sorry Luke you’ll have to do better than that; and as I mentioned I’M A SWINGING VOTER (sorry for shouting)
Tony nice to see you back here and look forward to some of your energy posts in the future
I heard the Bruce Highway and all my best to those affected in Rocky
but garlic is great
When our family moved to Labrador (near Southport) in 1960, as, er, ‘Mexicans’, we were astounded by the number of houses on ‘stilts’.
However, Insurance companies can demand all they like for houses to be placed on stilts.
All that happens then is that occupants just build in underneath, which is exactly what happens now.
In 1960 when we moved here, it was just the full 3 bedder on top of exposed stumps, and as far as the eye could see. All that was downstairs was the laundry.
We did the same, when in the late 60’s, we moved to Anglers Paradise (now Runaway Bay) into a new home. It was a 3/4 bedder on top of tall concrete stumps. In the mid/late 70’s we Besser bricked the underneath, put in 2 roll a doors, and a large pool room. Voila, house fully enclosed now and now that downstairs also at risk from major flooding.
In the 68 Cyclone and later the 74 flood, The Broadwater came up virtually to the foot of the front steps, mainly from the King tide and the amount of water flowing down the Nerang pre Hinze Dam, and into The Broadwater.
After that we did all that work downstairs. Memory is short!
Tony.
Tony,
At least in those days the council [and everyone else] would tell you where the the record floods came to. I built a house in 1973 on land that was below flood level and the GCCC wouldn’t let me build any habitable rooms below flood level. When the ’74 flood came I only had a problem with stuff in the garage.
There were of course old houses below flood level [often on stilts but some on the ground] but now there are new homes built below flood level.
Corruption somewhere.
Old Jack Gaven, the local Country Party member, had a farm on the river at Nerang and gave me good info on huge areas inland from the coast as he had ridden and swum his horse through much of what is now Gold Coast suburbia in numerous floods.
Couldn’t get on to anyone at SEQ Water after hours so I left a message with John-Paul Langbroek to try and get someone to dump water out of the Hinze before the cyclone arrives.
He lives on the river so he should be getting nervous about now.
SD,
Jack Gaven, Ern Harley and Cec Carey ran tight ships back then. (well except maybe when Cec canned the original Gold Coast rail link that is)
Farbeit from me to suggest that the rot set in at around the time that the ‘Think Big, Vote Small’ campaign started.
Tony.
another type of flood mitigation
http://wattsupwiththat.com/2011/01/14/bogus-claims-on-australia-and-brazilian-floods-from-abc-and-dr-richard-somerville/#more-31662
or maybe not ….
(Jennifer gets a mention)
and a link to ‘the big wet’
http://www.bom.gov.au/lam/climate/levelthree/c20thc/flood7.htm
So much armchair opinion and so little knowledge.
Wivenhoe had released almost all of its flood storage before the intense rainfall began on Sunday night. I live near the river and my commute includes the Moggill Ferry subject to river levels so have an awareness of what is flowing down the river. The fact that the records don’t include the weekend doesn’t mean they took the weekend off. Look at the records for Esk http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type=dailyDataFile&p_startYear=2011&p_c=-328476830&p_stn_num=040075 and you will see the that by 9am on Monday, 130mm had already fallen in the Wivenhoe area. The rapid increase in Wivenhoe levels was due to local rainfall – well before any upper catchment events arrived. That rainfall was also widespread over the upper and lower catchments. I will be interested to see just how much total rainfall passed down the rivers downstream of Wivenhoe; the Bremmer, the Warrill, Lockyer Creek etc. Over and above this, parts of Brisbane were already experiencing localised flooding on Monday due to the rain and well into Tuesday when we were making preparations to evacuate our offices which were eventually inundated.
Flood storage in Somerset Dam (upstream of Wivenhoe) exceeded it’s rated flood storage capacity resulting in inundation of parts of the township of Kilcoy further upstream. This was a brave move and likely to also have some fall out in the weeks to follow. They were in effect sacrificed for Brisbane!
I suggest you dig deeper into exactly what Anna Bligh meant when she said “loosing control”. I will give you a hint. Wivenhoe was modified in 2004-05 to meet revised flood event parameters (google Wivenhoe Alliance) to incorporate an additional emergency spillway that is fitted with tipping buckets that automatically and sequentially trigger at increasing water levels, somewhere just above level 75m ie above the maximum level reached in this event. These devices are designed to protect the integrity of the Dam wall but result in increased release over which the operators will have NO control and result in a lower maximum holding capacity. Clearly, an undesirable outcome. I believe Wivenhoe can hold water to the top of the wave wall at 80m but this would be under conditions where the emergency spillway would already have triggered all the buckets. This would make the recent event look like child’s play but could conceivably include say a failure of Somerset dam. The term biblical proportions would surely apply.
So in effect, by managing the releases to the maximum controllable level, the operators did the best that they could given the rapidly changing circumstances and inflows into Wivenhoe and Somerset. I for one have no criticism of that.
As to whether they should have reduced the water storage levels (not flood storage) below 100% in anticipation is a different question. This is after all, Brisbane’s major supply dam and it has seen 10 years of draw down since we last experienced 100% levels. Recent discussion in the media criticized the release of the flood storage and many were critical of allowing that water to go to waste particularly with rapidly escalating water charges.
Wivenhoe has flood storage for mitigation. Mitigation does not mean prevention. Did it achieve those aims? After cleaning mud out of a neighbors home today, it is hard not to look for someone to blame. They were flooded in ’74 so are uninsured. For me, it represents how little we can control nature in all it’s ferocity. I would suggest that those who criticize, read the eye witness accounts of the residents of the Lockyear Valley to get a glimpse of the scale of this event before pointing fingers at the operators. I have spent several years building dams and watching flood events as part of the job. So perhaps I am not surprised as much as others. In my (trained Civil Engineering) opinion, anyone who claims a different operational regime could have saved Brisbane has little comprehension of what just occurred in Brisbane. By some reports, 7500 GL fell in the catchment. Wivenhoe can store 1450GL or just 20% of the rain event in flood storage and only 35% from empty. Somerset, 500GL from empty. So exactly how can these dams have any significant effect given the sheer volume over the catchment? All they can possibly do is mitigation. I think that was achieved.
As with ’74, I suggest “look at the Bremmer”!
Well, at least TC Vania has subsided to a Low so SSTs can’t be too high at lat 25 but TC Zelia near Willis Is is now a cat 2, expected to deepen.
I’m trying to waltz these troublemakers eastwards because not only does that improve our prospects but big cyclonic systems a thousand miles away suck up all the moisture and give us a chance to dry out.
Craigo; I don’t mean to make you defensive but I think the point is that more mitigation would have been achieved had no releases been necessary at the relevant time and no releases would have been necessary had the dam been less full; but I stand to be corrected
Precisely how much more mitigation I don’t know
When the the dam was built surely there was a recommended maximum level. We are led to believe that this level is the 100% that is talked about. The dam has moved from being primarily for flood mitagation to being primarily for water supply, is this true?
Val, read my post @ 9.01am for the timeline,and two possibilities for space gains if the dam had been lowered below 100% in the few days available for big releases. Remember,lowering below 100% is not operational policy,as the extra 1450GL is regarded as the flood mitigation function of the dams tasks. Maybe it will become temporary policy option until the dam can be raised,but going below 90% will worry people if the shortfall isn’t made up relatively quickly by the end of the wet season. Taking it down 10% only gains 116.5GL.
The upshot of my two possible scenarios @ 9.01am is that not a lot of space could be gained in the time available before the flood rains,without causing moderate flooding downstream at a time when the river was already at minor flood. Gaining 200GL is not a lot in context of the catchment falls of the three days to 12/1,and the week overall.
I think Craigo has got it right.
Looking at the catchment above Wivenhoe falls,six day totals to the end of the rainfall saw the entire upper Brisbane catchment average at least 350- 400mm,with the eastern edge receiving 500 to 900mm. The lowest falls occurred at the very top of Cooyar Creek[c. 200mm] near the Bunya Mtns. the highest were in the upper Stanley [800+mm] and down to Mt Glorious [700+mm]… the distribution is not unlike 1974,which was higher around Mt Glorious,but lower west of the Brisbane River on average.
Averaged across the entire basin above Wivenhoe,I think this event was similar or barely below ’74,though ’74 had a bit of lull in the middle.
1974 was generally worse in the Bremer and the Brisbane suburbs for totals,similar in the Lockyer for totals but with not as many intense bursts that produced the extraordinary flash flooding.
Peter c, the dam was dual purpose,but with water supply the primary function according to SEQwater. The mitigation volume is a little more than the water supply volume.
I find it hard to believe that the dams primary purpose was for water supply. I would not believe what SEQwater says.
The dam was constructed as a direct result of the 1974 floods. It’s main purpose was to stop Brisbane being flooded. It has failed because it had too much water in it. The city needed more drinking water so instead of building another dam for that purpose they comprimised Wivenhoes major purpose. This is typical political short sightedness.
But why Poly is the question when the forecasts were all pointing strongly to exceptional rainfall was it deemed wise to keep so much water in the dam
We can agree that the Guardian is a warmist mag, so it comes as a surprise to find they have a story by Germaine Greer on the Queensland floods.
http://www.guardian.co.uk/environment/2011/jan/15/australian-floods-queensland-germaine-greer
Is this the beginning of the MSM accepting that natural variability is extremely noisy, the CAGW signal nowhere to be seen?
Political dynamite! The people are more concerned with disastrous floods now, not sea level rise in some far distant future.
Why,Val? Precisely because its water supply is the prime use,whether Peter C finds that hard to believe or not. And were the forecasts for ‘exceptional’ rainfall? As in 400-500mm in two days? I don’t think they knew how much was likely until just about the day,by which time they were upping releases.
They are required to keep it high if possible. The dam had been mooted before 1974,in fact in 1971 a report had been drawn up and water supply with flood mitigation were the aims then. I think land acquisition was under way by 1973.
The 1450GL flood reserve was designed,as Craigo said,to MITIGATE,not prevent major floods. They knew about the scale of 1893’s month long flood,which also became stimulus for dam proposals in its time. They realised that such a volume could never be stopped utterly in its tracks,and of course they knew that the Bremer ,Lockyer and Lower Brisbane were well capable of putting a moderate flood into the river in their own right. So there was never any pretense to literally ‘stop Brisbane being flooded’. I think that was an assumption to begin with that became a truth. Have people forgotten the 1996 flood? I guess so.
I’ve known since I were a lad that Wivenhoe was claimed to be able to reduce a 1974 flood by about two metres…not prevent it. This was I assumed common knowledge,but maybe that was restricted to the ’74 ‘flood generation’.
Wivenhoe did not fail,Peter. It may not have worked out to the optimal scenario,but it certainly prevented a higher flood.It strongly affected the way the total flood volume generated by the upper Brisbane arrived downstream. It held back 1400GL that a dam without such a reserve could not have done,and slowed the arrival of thousands more GL. This flood without Wivenhoe would have been as high as 1974,maybe more,but not of such duration as that flood,which was above major flood level at City gauge for 4 days. I think Wivenhoe reduced the peak by less than hoped,but it still reduced the peak..and the duration.
1974 produced greater local flooding from the Brisbane creeks,which combined with storm surges off Moreton Bay to push the river up before the main and Bremer river water arrived.
I suspect that when SEQ water started dumping big quantities [130 gl/day] back in early October for the first time in 10 years and caused a lot of destruction and minor flooding downstream, the locals had a bit to say and as a result management possibly overstaid their hand.
And if you don’t think SEQ Water knock off on the weekend just try getting in touch with them.
Been trying all their emergency numbers with no luck. The govt emergency number told me there is no one to speak to. I had to send an email.
Not only no one on watch–no one on board!
Check it out Craigo!
Hi Polyaulax,
Surely in the proposal and subsequent construction of the dam the recommended maximum level for flood mitagation was stated.
You seem well informed on this matter, maybe you know where to look.
here’s an article from a now retired journo who says ‘I guess I have probably seen more floods up close than anyone still alive. Between 1949, when I arrived in Brisbane from Sydney, and 1997, when I retired, I covered almost every major flood in Queensland and northern NSW.’
http://www.couriermail.com.au/news/sunday-mail/this-town-has-seen-it-all-before/story-e6frep2f-1225988533849
SD – sorry, can’t comment on who is or isn’t contactable by phone on the weekend.
I worked on the construction of Paradise Dam on the Burnett River that so recently mitigated the flooding in Bundaberg. That dam can be operated from several locations including remotely from an office in Bundaberg.
You are correct in your comment about “unpopularity” of previous releases. There were a lot of complaints about previous releases particularly when they combined with higher than average tides causing some local flooding. That would be contrasted by the reports that we should be storing extra water e.g. http://www.couriermail.com.au/news/plan-to-raise-wivenhoe-dam-storage-level-for-drinking-water/story-e6freon6-1225839328569 but La Nina hadn’t really made the headlines yet.
The news releases for Wivenhoe water releases are here http://www.watergrid.com.au/news and track the releases and warnings. Noting that 60 – 80mm of rain was received in the prior week Wednesday-Thursday.
Peter C – some light reading here about options reviewed in 2007 http://www.qwc.qld.gov.au/planning/pdf/support-docs/provision-of-contingency-storage-in-wivenhoe-and-somerset-da.pdf Note that flood modeling data was revised in about 2000 (ANCOLD Flood Guidelines) resulting in a series of major renovations to many dams around Australia to handle increased rain events.
The only question that I see is whether an earlier release below the 100% water storage level was warranted. When and on what basis that decision would be made and then what would be the impact of that decision on long term water security? These questions cannot be answered with hindsight, only what was knowable at the time of those decisions. Was the forecast rain going to be spread over a number of days which would be manageable or in fact was it known that it would arrive in a massive short event? What rules are currently in place and who had authority to make decisions to change those rules if necessary? In other words, given the same information available at the time, was there a better way to manage the dams?
And we haven’t even begun to question the role of the Wivenhoe lungfish in all of this.
Jen,
http://itia.ntua.gr/dk
http://itia.ntua.gr/en/docinfo/23/
http://en.scientificcommons.org/d_koutsoyiannis
http://en.scientificcommons.org/35486770
http://www.griffith.edu.au/__data/assets/pdf_file/0005/262184/SevereStorm_10.pdf
http://www.coastalconference.com/2007/papers2007/Peter%20Helman.doc
Thanks for that Craigo. Even if it were on remote, someone should still be contactable somewhere.
Re the Wivenhoe lungfish: I’ll bet they wouldn’t be there if there was no dam, particularly over that last dry 10 year period.
It would be interesting to accurately compare the biodiversity of a dam site before the dam was built and 30 years after. I’ll lay odds that the existence of the dam improved the biodiversity. [With or without Boggomoss Snails.]
Hi Craigo, I have had a quick look at that light bit of reading. There was a recommendation to raise the FSL (full storage level) by two metres (Option W1A, operational change). This means raising the storage level without any increase in dam wall height (all other options required raising the dam wall). This would mean reducing the flood mitagation compartment of the dam.
Excerpt 1.4 paragrah 3.
“Option W1A has impacts on the flood capacity of the dam for events greater
than the 1 in 1,000 AEP event.” AEP (Annual Exceedance Probability)
This increase would raise the level to EL69 (EL means elevation level above a mean sea level in metres)
The question is was that recommendation implemented and is EL69 the new 100%?
Peter C, this is how I understand it:
The 100% full point at Wivenhoe is at the first spillway and that is about 20 m below the highest spillway.
The highest spillway equates to about 230%.
The first spillway can be closed or part opened with radial gates to control flow.
There are also water release mechanisms for when the dam is below 100%.
SEQ Water seem to be looking at a range of options including [recently] considering trebling the size of the desal plant.
For a fraction of that 4 billion they could double the capacity at Wivenhoe and still have the same amount of flood mitigation.
Spangles, 100% is EL67m, full flood is EL74, but it will go up another couple of metres at least, secondary spillways at EL 76 or something like that. It was certainly of 74m during the height of the inflows.
The lip of the concrete in the main gated spillway is EL57 which is about 35 or 40% I believe.So the big gates sit on top of that level,and they are 16m tall. That makes 73,so maybe there is some other structure adding an extra few metres that I have not accounted for.
So once you get down to the lip the only way out for water is through the small hydro system/outlet works which I think can do 1.5GL/day
Having been dubious about Wivenhoes flood mitigation capabilities, I have followed events very closely over the past week. With the benefit of the data provided on the BoM website and information issued by SEQ Water, I believe that SEQW were “asleep at the wheel” on Friday, 07 January in not operating the dam correctly which has contributed to a flood levels in the Brisbane River being at least twice what they needed to be.
For the past 3 moths, we have been in a strong La Nina weather pattern with 3 months of the wet season still ahead of us. On Thursday, 06 January, the BoM forecast an extreme rain event for the SE corner of the State over the next few days with falls of between 200 and 300mm. This event was confirmed with areas in the Wide Bay hinterland recieving up to 350mm on the Friday and with the system moving south. Why then, with the dam at 106% capacity at 6.00am on the Friday morning did SEQW not increase significantly the release from the dam.
It was not until midday on Sunday when significant falls of rain were recorded in the Upper Stanley catchment that they began to react by increasing the release to 215 ML per day, causing less than minor flooding downstream. However, by 9.00am on Monday, the storage was fast approaching 150% and continuing upward with no increase in discharge. With more rain falling across the wider catchment area on Monday and particularly with the huge “dump” over Wivenhoe itself early on Tuesday morning, the situation became critical.
It was not until 9.00am Tuesday, with the dam at 175% and continuing to spiral upwards, did they open the gates to release eqivalent to 640,000ML per day (approximately 50% of the storage capacity). With that release for the next 14 hours, they were able to maintain the level under 200%, however this surge is what has significantly contributed to the major flood peaks in the Brisbane River below.
I am sure that the experts will have many ways of looking at and interpreting the data to review the action that SEQW have taken during this crisis. I am sure that SEQW will continue to justify what they have done and spin the line that “the dam has saved Brisbane from what could have been a worse flood”. However, I maintain that based on the data, flood levels could have been at least 50% less if they had taken action on Friday, when the rain event was verified, instead of Tuesday when it was far too late to avoid a major disaster.
While flood modelling is a complicated process, a simple exercise in maths will help demonstarte the veracity of this argument. At its peak, 640,000 ML per day was released in the 15 hours between 9.00am and 12.00 midnight Tuesday. That is a total 400,000 ML. Had increased releases been made earlier, say by 9.00am on Saturday (when the rain event was a reality) for the next 3 3/4 days (till midnight Tuesday), increases could have been kept to less than 110,000ML per day. This of course would be on top of what was already being released over the weekend, but probably totaling around the 300,000 ML per day currently being released which is only causing minor ongoing flooding.
I know that there are other matters such as the effect of the Bremer River and tides that will determine final flood levels, however from the simple evidence, it is plain to see that the dam flood mitigation capability has been grossly mis-managed by SEQW. This has contibuted to significantly higher flood levels all along the river with the resultant property and infrastructure costs totalling $billions as well as misery and hardship for tens of thousands for years to come.
Hopefully an Inquiry or Royal Commission will get all the facts on the table, so that action can be taken to reduce any future flooding to a minimum. Ofcourse there is a lot of politics in this; it will be more than just bureacratic bungling. While he has been able to maintain his composure to date, Campbell Newman is absolutely livid and cannot wait for the process to begin following the clean-up. I wonder who will be the first to bring a class action against SEQW for negligence.
Poly, thanKs for that.
I think there is a frame above those gates that would account for the extra meter, however you are saying that 125 of that 225% figure is contained in the top 7m [9.5%] of the dam.
If you draw a diagram of any shape dam it is very hard to achieve this and I wonder if they are are truthing us on it.
It could be right but it would need a phenomenal spread of water in the top 7m and that valley doesn’t appear to have those characteristics.
When I camped up there a few months ago and it was supposed to be 100%, the emergency spillway was around 20m above the then surface level. That spillway is at the northern end and is one of the few places you can access easily.
interesting perspective on dams, including Wivenhoe, by Barry York at OLO today…
http://www.onlineopinion.com.au/view.asp?article=11488
“Had the Greens been as influential in the second half of the 1970s as they have been since the mid 1980s, it is unlikely that the Wivenhoe Dam, on the Brisbane River, 80 kms from Brisbane, would have been constructed (after years of planning and building, it was opened in 1984). The Wivenhoe was designed, following massive floods in 1974 (on current indications, worse than the present Brisbane flooding), with a flood mitigation function alongside the usual water supply role. Like all dams, it is an example of human beings changing the natural world, by unnatural means, into something very useful and necessary to us in terms of our needs, standard of living and future progress….
“To the Green mentality and ethos, changing Nature is destroying Nature, dams are an assault on the ‘delicate balance’ in Nature, an example of human arrogance going ‘too far’. In this regard, the Green mentality and ethos are quasi-religious. The late Michael Crichton put it neatly in a speech to the Commonwealth Club in San Francisco in 2003 when he talked of the ”remapping of traditional Judeo-Christian beliefs and myths’. He said:
“There’s an initial Eden, a paradise, a state of grace and unity with nature, there’s a fall from grace into a state of pollution as a result of eating from the tree of knowledge, and as a result of our actions there is a judgment day coming for us all. We are all energy sinners, doomed to die, unless we seek salvation, which is now called sustainability. Sustainability is salvation in the church of the environment. Just as organic food is its communion, that pesticide-free wafer that the right people with the right beliefs, imbibe. Eden, the fall of man, the loss of grace, the coming doomsday—these are deeply held mythic structures. They are profoundly conservative beliefs.
“It’s good that he identified them as ‘profoundly conservative beliefs’. They are very reactionary beliefs.
“As has been pointed out many times at this site, it is indicative of our strange times that opposition to dams, as a matter of principle, can be seen as left-wing. What is the traditional practice of left-wing parties in power on this question? What is the left-wing theoretical foundation for a policy on dams?
Interesting. On 13th January I posted an article on the way the panic release from Wivenhoe on Tuesday 11th produced the flood peak in Brisbane 36 hours later. And from Andrew Bolts Blog to Jo Nova’s, and now the Australian and other papers, hydraulic engineers are asking why the buffer was allowed to get so full that they had to discharge the full volume of inflows during the same period. Most 4 year olds can understand that the more you use something up the less of it you have left. The same certainly applies to flood buffers.
It has since been revealed that discharges on Sat/Sun 8th and 9th, and presumably on Monday 10th, were only 100,000 ML each, the volume of inflows produced by an average of just 42mm of rain over the catchment, or 14mm/day. Note that there is still about an average 12 hours warning between when the rain falls in the eastern part of the catchment and when it gets to either Dam. Clearly, a modest extra 100,000 ML/day of discharges over those 3 days alone would have halved the subsequent panic release to 345,000 ML instead of 645,000 ML. In fact, a pre-release of 300 Gig would have left another 19.5% in the buffer and the 200 Gig daily releases could have continued to smooth out the flows. The flood peak release was entirely avoidable.
But here we have Jen, fresh from her 6900 ML/day Snowy Hydro beat up, running an article on 14th January claiming “There is absolutely no doubt whatsoever that this monster dam played an absolutely crucial role in preventing what could have been an even worse disaster.” Well, I guess we will have to let history be the judge of that, won’t we?
Stephen,where is your evidence that a 640,000ML/day release was maintained for 15 hours? This is a critical question for determining peak height. I cannot find any support for 15 hours at that volume.
As far as I understand it,the 640,000 [or 645,000Ml/day as I’ve seen it] figure is a peak flow-during an hour or maybe even less-,not sustained flow.
Hourly online figures for the river below the dam are available at DERM’s water website and the transient [one hour] flow does not exceed 600,000 ML at any time. This downstream figure also includes Lockyer Creek flood waters and local run-off,so you have to subtract that to get at the real Wivenhoe hourly/daily volume. If 15 hours at 640,000ML/day was true,we’d have seen an hourly peak well in excess of 700,000 ML at the gauge including Lockyer.
We really need to wait for real analysis.
This can be a difficult thing to explain, so that it is understood.
That release of 645,000 ML was shown at the SEQWater site Home page at the time, and that page is updated daily, so you will never see it again unless someone took a screen shot of the page at the time.
Now, that release of 645,000 ML is a ‘rate of release’, meaning that if the current (at that time) amount of water being released through all 5 gates was kept up at that rate, then over a full 24 hour period, that 645,000ML would have been released, if you can see that.
This is the link to (current) Home Page for SEQ water:
http://seqwater.com.au/public/home
In some small way, they also have better tried to explain that release ‘rate’, saying there that:
“Wivenhoe Dam is at 123% and dropping, discharging around 299,000 megalitres a day (etc)”
This is the (Current date) link to the latest dam levels:
http://seqwater.com.au/public/dam-levels
This shows Wivenhoe releasing from storage, Somerset with minor releases from storage and almost back down to 100%, and incidentally Hinze dam lower than 100%.
Tony.
That’s right,Tony.
For reasons best known to themselves, SEQwater and WaterGrid use ML/day as an expression for what would best be described in cusecs/cumecs,when it should really only be used for true full day quantities.
They could also simply add a little more to each media release,noting the mean daily volume in ML or GL for the previous day,or a specified 12 hour period for that matter,so one could have a better idea of 24 hour volumes.
This current usage of theirs is causing confusion.
Poly,
You are certainly more informed than me (I have not professed to be an expert) and I appreciate yours and Graigos insightful comments. However, a full independent inquiry is needed to get to the bottom of it as we will not know the exact details of release rates, timing,etc.
I have simply gone off the SEQW media releases for the rates and the data from the BoM river height information at Lowood to estimate the timing and duration of releases which I know is not entirely accurate.
However, even given that the duration of the peak 645,000ML/day may have been shorter and therefore the total discharge over the period somewhat less than 400,000ML, it only adds weight to the argument that commencing Saturday morning (when the forecasts were becoming a reality on the Sunshine Coast hinterland), a steady release of around 200,000ML/day (up from around 100,000ML/day) was possible and would have preserved a significant portion of the flood capacity for the deluge that occured on Monday night and early Tuesday morning. Given the predicted rainfall and inflows over the weekend, it is unlikely that the dam would have dropped below the “precious” 100% either.
I appreciate that this is all good in hindsight, however if SEQWater cannot act on validated forecasts from BoM, there is something tragically wrong with the system. Some independent experts are beginning to say the same thing. A full enquiry needs to be commissioned ASAP; we all have a right to know what went wrong.
Hindsight is a wonderful thing. Yep,there was a window for greater discharges,but let’s not overstate the potential with lashings of that hindsight.
Well,Bligh has announced an inquiry to report in 12 months…hopefully,SEQwater will shed light on their precise releases before that. If they are prevented from doing so by the terms of the inquiry,there’ll be anger,I’m sure.
Stephen, a steady 200GL all day will cut all the bridges down to the Bremer junction,and will back up Lockyer and the Bremer,if they are in flood,so it has to be carefully done. It will not be possible in all circumstances.
These post flood releases are at about that level,or were yesterday. Mt Crosby is above moderate flood level still.
Reading through the raising proposal document,I’ve discovered an interesting nugget: the volume of water between top of the gates at FSL 67m and the concrete lip at the bottom EL 57m is 760GL.So if the need to suddenly lower the dam from 100% arises, 60%/760GL can be disposed of via gate opening. To do that in one day would of course cause a massive flood,in two very big flood,and in three an above moderate one.
Thanks for the info Poly, a couple of questions that you might have an answer on.
Why is Mt Crosby still at “moderate” flood level while downstream at Moggill it has been “below minor” for the past few days? Hopefully the water is not going too far back up the Bremer.
Also, any idea why the data for Lowood has not been on the BoM site since last Friday?
It is also interesting to look at the consistent decrease in Wivenhoe between Friday and today.
Had SEQW some foresight (it obviously was not in the “operations manual”) to do a similar thing the previous week before the rain event, we may not have needed the full RC and we would not be having this conversation.
SD et al (repeating poly’s clarification)
Stream bed level at Wivenhoe is 23m AHD (Australian Height Datum or roughly above mean sea level)
Current water storage operating level is still 67m.
Emergency spillway – an open uncontrolled ogee crest with fuse gates that first triggers at 75.8m (built by Wivenhoe Alliance – see here http://www.leightoncontractors.com.au/verve/_resources/wivenhoe-dam-alliance.pdf) See also The Australian on 15/01/10 http://www.theaustralian.com.au/national-affairs/state-politics/experts-trying-to-balance-flow-of-wivenhoe-dam-almost-lost-control/story-e6frgczx-1225988034297
The crest of the dam is 79m with a 1m wave wall to 80m.
I think the nominal 225% full is around 77m. See Storage Capacity Curve http://www.qwc.qld.gov.au/planning/pdf/support-docs/section-3-15-wivenhoe.pdf
Wivenhoe is in a very flat valley and has a large increase in surface area with increased height (think cocktail glass) At 67m, it has an area of about 11000ha and increases to about 18000ha at 77m.
Another point not explored is that increased discharge increases the level of the tailwater (currently not reported by BOM but I suspect it has drowned) which will increase the velocity of the streamflow and thus reduce the time taken to move down stream but is then complicated by other downstream levels etc etc so it gets into more complex hydraulic modeling. Just reading the reports from the tug boats demonstrates the increased speed of the river. So all the numbers for co-incident peaks etc may change and question the “man-made flood” hypothesis.
In any event, I welcome an inquiry but suspect that as with all inquiries, someone needs to know what the right questions are and who the right people are to answers them. Then it will probably be written in techno-legalese that will only confuse the picture. But after all is said and done, living on a flood plain does carry the risk of flooding. It’s just the depth that varies and I remain unconvinced that mitigation failed.
Stephen, at Mt Crosby,there is a weir and the water-supply draw off,while the river is tidal at Moggill and is wider and deeper. So,very different river profiles,including bank heights.
Lowood may have been damaged. A lot of sites were,particularly in the Lockyer.
Since Friday,they have been discharging Wivenhoe at around 300GL a day to get the flood reserve back to ‘safe’ at 100% 1200GL in four days. The dam level has dropped by less than 70%,which is about 800GL. 1200 + 400 = 1600Gl for inflows since Friday: there is still a bit of a flow coming into the dam! This slows down as it hits the river bed,so 24 hours is seeing about 200-220 GL of Wivenhoe go past Savages Crossing.
Please note the initial blog post has just been update with more information from Tony.
Conspiracy at SEQ Water??????
SEQ Water both in their new and their old websites have only ever reported on business days, generally 5 days a week. I have been monitoring them for years. Nothing to see here.
If you want real time monitoring, check BOM for the river levels. Wivenhoe Hw gives you the dam level. Unfortunately, they only display the last few days of record but a phone call to their local office and a small payment will get you all the data electronically.
Tony is wrong about when the rain started.http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type=dailyDataFile&p_startYear=2011&p_c=-328476830&p_stn_num=040075 Clearly by 9am Monday, 130mm of rain had fallen in nearby Esk. Similar values are available for the upper catchment. Use the link and check the records. Note as with SEQWater, the reading for Monday 9am is accumulated from Sunday 9am to Monday 9am. Most of it in the early hours of monday morning.
The rise in level before the weekend and the trigger for release commencing on 06/01 was about 80mm of rain in the upper catchment the previous week including releases from Somerset.
I live near the Brisbane river. I cross it at least twice every day. I looked at the COLA website http://wxmaps.org/pix/prec7.html and it was clear that it was going to be a wet week in SEQld. Our factory in Wacol was flash flooded on Monday morning from the local rain and roads were cut by creek flow. Our office floor drains backed up and the toilets weren’t flushing! I spent most of Tuesday morning trying to estimate flood levels in our factory then sand bag the doors which was a bit difficult with the yo-yo predictions. Final result, about 200mm through the office which was about the level I had estimated at midday. I then dashed home in time to get through the flood waters and spent the next few days isolated in Moggill watching the river flood the local streets not far from my house. I had also stocked up on iron rations in December after a wet spring and full dams in a La Nina summer. It was common knowledge that local flooding was possible. As of yesterday morning, there were still houses in Kenmore flooded due to the still receding river levels.
One day soon I hope to use the Moggill ferry again. It cuts about 10km off my commute and avoids rush hour traffic.
Wivenhoe dam release too little, too late.
http://www.theaustralian.com.au/in-depth/queensland-floods/engineers-emails-reveal-wivenhoe-dam-releases-too-little-too-late/story-fn7iwx3v-1225991990957
I believe SEQW release strategy needs to be reviewed. Imagine if they released 200 to 300 GL per day in October 2010 and Dec 2010 when Wivenhoe hit over 120%. It would have cause unacceptable flooding to many suburbs along the Brisbane river. Imagine what the public would have thought about that.
Meteorology is not an exact science and can not be looked at purely from a crystal ball position.
A revised release startegy can not just be written aournd just a January 2011 scenario. There are many rain fall scenarios that need to be considered with a release startegy that best covere teh full range of hypothetical scenarios.
More dams would help storage & flood problems, but I think Peter Garret was worried about lung fish (and other species). Wivenhoe is full of lung fish and Wivenhoe has no fish ladders??? I’m no expert on the environmental impacts of dams, but I think it’s worth asking the question.
During the panic when the gates at Mivenhoe were opened to release 1.2 Sydney Harbours down the river, It had to be known that Brisbane would flood like 1974 and in 36 hours, where was the urgent warning from the government?
For those that had power they may have seen or heard the advice to leave low areas, that’s not good enough, we needed an urgent warning of an imminent flood like 1974 in 36 hours.
Many people that I helped said they had no warning, they lost everything, they found themselves in floodwater in the darkness.
Tony said:
No that’s not true. It started around 11 am on Sunday morning as you can see on the radar and it was pouring all afternoon. Wivenhoe was already at 68.55 m at that time, so the manual gave them the authority to release the entire dam’s inflow or 3,500 m3/s (which ever is the lesser, 3,500 m3/s being the maximum non-damaging flow), right from 11 am Sunday morning.
When did they actually release 3,500 m3/s you ask? Not until 44 hours later after they had already hit the panic button to save the dam.
How much water was held back in the dam compared with releasing 3,500 m3/s over those 44 hours? About 220 Gl compared with the 280 Gl flood dump in excess of 3,500 m3/s they released on Tuesday and Wednesday.
Albert said:
This was a consequence of the dam operators not realizing they were going to lose control and cause a major flood until early Tuesday morning (it hit 73.5 m at 6 am) and even then they took too long to warn the authorities. The warnings should have been going out early Tuesday morning, e.g. they should have been in 8 am news bulletins at the very latest. But everything about the dam operators’ response, until the dam was in danger, was slow.
I read on the weekend that the giant floodgates on the Wivenhoe dam can release more water than any other dam on Earth and this seems to be true when you see the massive release on Tuesday night which fits the BoM graph perfectly, the release turned minor flooding into major flooding.
I made the connection immediately when I read this comment, it was insane to let an earth dam approach overtopping when a full flow release for some hours will flood Brisbane. Eliminating the possibility of overtopping should have been the priority and not saving drinking water with this particular earth dam. Very bad management and obviously not considered. You must never ever approach overtopping, you should err on the side of safety.
I calculate that when the gates were open fully, it would have taken 2 hours to reach Jindalee, where I live, 2 hours at 25 knots seems right.
There was no warning that a “bomb” equivalent to a breach in the dam wall was headed our way and the river would rise rapidly in 2 hours as it did.
Warning about flooding means nothing to people who weren’t here in 1974 and 2 metres at the city guage also means little. Why were’t we warned of a bomb headed our way in 2 hours in the darkness?
I am a resident close to the Mt Crosby Weir / Colleges Crossing area and regularly cross the river here when doing shopping or heading to work. To be honest I cannot see where the dam operators went wrong – there is missing information for the 9th-11th weekend period but I can confirm that the river was pretty much at breaking point then, at least around this area. Colleges Crossing had been flooded for days and the waters were consistently 70cm below the Mt Crosby Weir, which for those who haven’t seen it has one hell of a clearance. During the previous week there was only one 48 hour period where waters dropped, but for at least 4 days beforehand water was lapping at the base of the Weir. Interestingly it had been at this height for probably 2 days out of 3 over the last few months with the La Nina weather system since August 2010 and the water height recorded on the BoM river height data for the Mt Crosby Station seems to indicate that they closely managed the river height right on the Mt Crosby Weir’s maximum height – this seems to make sense as the next non-flooded river crossing is the Centenary Motorway bridge at Jindalee which would have been a logistical nightmare (the road is already a friggin parking lot in peak hour without the extra volume of the entire western suburbs and a lot of Brisbane-bound traffic from northern Ipswich joining in).
It then gets interesting – it was pissing down with rain on the weekend and I got home on Saturday evening and saw the Weir only had 50cm clearance. Seems it might have just been the heavy rain the stalled frontal system was dropping. When I headed to work at 4:30AM Monday morning however the Weir was in full flood and during Monday the water level increases significantly (I visited a few times since I had nothing better to do that day; told work I wasn’t driving the Jindalee route just for a 4 hour shift). For this to happen they would have been ramping up releases on Sunday, so that indicates they started to really release water ABOVE the rate they usually do on the weekend.
Friday:
Somerset – 107.2% (rising)
Wivenhoe – 106.3% (rising)
Monday:
Somerset – 154.7% (rising)
Wivenhoe – 148.4% (rising)
They were operating according to the manual, which requires releases to bring the dams down to 100% occurring no later than 7 days after the 100% level is surpassed. So on Friday things looked pretty peachy despite dam levels rising; if you look it was at 120-130% levels about 3 times in the previous 4 months and they were able to hold releases at the rate that kept the Mt Crosby Weir from flooding. They were a mere 6-7% above the threshold on Friday and despite it rising they were well within the management level (you have to remember they didn’t have that steep curve to look at yet cos it hadn’t happened! They were at the bottom of it!).
Now, given that inflows would have become quite high they did have a 120% flood compartment so it wasn’t necessary for them to flood downstream properties initially; however in just a 36 hour window they did ramp up releases dramatically so that the Weir was hardcore flooded by very early Monday morning. In that time they would have realised this was necessary. The whole point of having a flood mitigation compartment is so you can trade-off flood height with flood duration, so filling the flood compartment with the immediate inflow so it can be released over a longer period of time at lower volume is what the entire mitigation strategy is all about. THEY HAD BEEN DOING THIS FOR OVER A WEEK! Sometime in that 36 hour window when the rain really started falling with the stalled front system, it became apparent the flood compartment was not going to be large enough to accommodate the inflows, so they ramped up releases and inundated downstream properties.
Really, the fact is only 6-7% of the flood compartment was filled when catastrophic inflows began and in less than 36 hours they were upping releases on the path to armageddon. Sounds to me like they managed it in a proper way. They could have dropped the dam levels below the 100% threshold, but they were already discharging enough water to almost put the Weir under and the dam had started rising rapidly. Therefore they would have had to do some pretty serious releases that would have caused major flooding downstream over a long period of time, perhaps over a week beforehand, and in the end when balancing out the inflow and outflow rates probably would only have shaved off 10%. Considering the dam at the height of the rainfall + Lockyer Valley flooding was filling at 10% per hour, you would have bought just ONE HOUR of relief (in fact, since the purpose of mitigation is to decrease outflow volume and increase outflow duration, you would have had even less than 1 hour of relief if the inflow rate was 10% of capacity per hour). Even then, we would not have been able to predict a stalled front weather system 7 days in advance anyway so SEQWater had no reason to ramp up releases.
Not to mention it is important to remember that the Wivenhoe-Somerset system only mitigates the Stanley and Brisbane River systems; the enormous inflows from the Bremer were unchecked.
Overall, they did the best they could with the information they had at hand. Even if they were funnelling in meteorological data and acting beyond the scope of the operating manual they didn’t have any reason to drop the dam below the 100% threshold until it was too late really.