Author : J. V. Hodgkinson F. C. A. Chartered
Accountant : Aug 2006 to November 2013
The principal thrust of this
This is my review based on official
statistics and documents. It is done in conjunction with Ron McMah, grazier
of Imbil and Trevor Herse, retired of the Gold Coast
2nd December 2013
The statement at the top of this page dated August 2006 unfortunately holds true today. The last seven years has enabled me to accumulate firm information to review and confirm the course of those years
I have come to understand that this conundrum is more difficult to assess than I imagined because it countermands the evidence of our own eyes.
However if the Conundrum of our water supply through the Wivenhoe/Somerset is understood, the answer to so-called "drought" and "flooding" can be achieved by natural means and with far less cost as I have outlined under section (B).
The conundrum occurs often
The Conundrum for the 2001-2007 period, which is representative of a large number of similar periods since records were kept, is difficult to see unless you have all the data. I have laid this out for your examination. You will see that mathematics/arithmetic/statistics is the principal guiding light and their need surpasses all other disciplines.
The conundrum is essentially "in the 2001-2007 period, why were our dams depleted to almost empty when the BOM rainfall stations in the catchments showed 99.1% in the Wivenhoe and 91.4% in the Somerset of the long term average of the rain producing Summer months December to March"? Those four months receive more than 50% of all rain since records were kept (see a little later)
The surprising answer is that rainfall
and the state of the dams have little in common. You will observe why and the
abortive attempts by our water guardians to make them match. The understanding
opens up a totally different and less expensive approach.
(A) Short review of our water supply in the Wivenhoe/Somerset Follows: Appearances can be deceptive.
(B) Our proposal for
severe "drought" and "flood proofing: Brisbane and mitigation in
Ipswich and Gympie Click
to proceed directly to this point and skip the water
Click for further information on
(A) Short review of our water supply
(1) Topical graphical features of our water supply
(2) Normal rainfall and storms
Management of our water supply
Our current dam managers are in danger of adding themselves to a long list of those deceived by this conundrum. It started with the Climate Change Centre Of Excellence click QCCCE supported by DERM with the so-called "Millennium" drought. It was followed up in more recent times by the Flood Inquiry and its reduction to 75%. Further evidence is the reconstruction of the roads at the same level without raising impeding free releases from The dam.
The matter is further compounded by the deliberate misstatement (admitted) of the allocation to the ecology reducing the yield of the Wivenhoe from 446,900ML a year to 286,000ML. This variation created by manipulation of a single definition is equivalent to the output of 3 1/2 desalination plants of the Tugun size. click Water Share for further information.
The structure of the SEQ Water Strategy, the fate of desalination and lower water costs now rest largely on this calculation.
Seqwater is central to the decision making process of water in South East Qld. Our relations with them have been cordial and constructive.
It is not surprising that both the Flood Inquiry and those in Seqwater that we have spent time with and I suspect most of us who live in South East Qld expect low level dams and "drought" outside the catchments of the Wivenhoe/Somerset dams to match. The Climate Change Centre of Excellence also believed this to be the case and went to extraordinary lengths putting square pegs into round holes (see tab QCCCE). The consequences of this simple statement not being understood have have had a profound effect on our water supply planning costing us billions of dollars with a strong possibility of running out of water of any sort.
On the other hand, the longest drought that we have experienced in South East Qld is the Federation drought 1898 to 1903 being 5 years in length. It is this drought that the Queensland Climate Change Centre of Excellence attempted to match the period 2001 to 2009 and failed after having to add at least two years where no drought existed anywhere in Queensland (BOM information).
With a 3.7 year "uncommon event" average in good times in the Wivenhoe Dam, it does not take much variation of the average to push us into periods longer than the federation drought.
I have taken the time to identify these "uncommon events" since 1840 by use of all BOM rainfall data in both catchments, flood information from BOM and flood heights at the Port Office having had written advice from the Head Hydrologist of DERM that 58% of the water that reaches the mouth of the Brisbane River comes from above the dams.
You will see from my constructed chart that 101 years of the 160 years of records had not received any inflows from " uncommon events" for 5 years or longer. There are two periods of 11 years.
The most recent period of 2001 to 2007, being 6 to 7 years was added to by the Climate Change Centre of Excellence by a further two years in an attempt to match the dams. However, BOM records had those two years 2008 to 2009 as recording rainfall at 125% of the long term average and not a drought to be seen anywhere in Qld.
When confronted with these facts most defer to a nonsensical term of "Green drought" or a "Climate Change" explanation. Seqwater will have to be careful not to fall into this trap as did their forebears with the term "Millennium drought" most likely used as an excuse for lack of preparation. However we wish to make it clear that this is not a witch-hunt but views put forward to clarify the situation.
This means that we are in a similar position to year 2001. With the dams full or near full how do we provide for completely empty dams for a further time of 6 years being the longest time 11 years less 5 years of a full dam if not interfered with in the method outlined by the Flood Inquiry by dropping the full level to 75% at the start of their wet season.
Premier Beattie's answer was the Traveston Dam, Desalination plant at Tugun and recycled effluent. With the cancellation of the Traveston, Premier Bligh left us in no doubt that we would one day be experiencing severe drought restrictions with desalination and recycled water kicking in at 40%. I have to agree with the exception that on occasions it will be severe for many years as matters now stand.
Most of this can be controlled and eliminated by the stroke of a pen and all of it including flood control when one reads "Our future" in (B)
With the advent of the Water Resource (Moreton) plan of 2007 the yield of the Wivenhoe/Somerset was reduced from a Seqwater published yield of 446,900ML annually to an a volume of 285,000ML annually which matches the total of all allocations to users. This reduction of 161,900ML annually is a massive reduction equivalent to the output of 3 1/2 desalination plants of the Tugun size at a capital cost of $4.5 billion plus running costs.
The fault is a mater of arithmetic and not hydrology or engineering. It is further explained at Water share. The two most senior members in DERM admitted to us that they had "tweaked" the system outlined by the Technical Advisory Panel. The "Tweak" from 66% to 78% for the ecology produced the discrepancy by a simple definition. It can be reversed in the same way.
(B) Our future : is here
Three days after this was tabled at a meeting with Minister McArdle, the flood of 2013 did exactly as predicted. With sufficient space in the Wivenhoe all water above the dam was withheld (our objective even for the 1893 flood) allowing us to observe the below dam Bremer River and Lockyer Creek in full flood without the blocking confluence normally created by the Wivenhoe/Somerset.
Brisbane and indeed Ipswich were flood free despite dire warnings from Premier Newman and Lord Mayor Quirk. I believe that it has produced an open mind for this relatively simple procedure. Premier Newman has advised us that if it "stacks up" it will receive greater attention from the Cabinet.
Their future: is Recycled effluent/other waste water and desalination
They would have our future in this direction which leads us back to the past. Ministerial statement (Hon Ed Casey ALP) on cancellation of Wolffdene Dam 1st March 1990
"I have further instructed the Water Resources Commission to investigate new studies into the water needs of South Eastern Queensland and to review all potential alternative sources including storages, ground water, waste water reuse, demand management and desalination" for FULL STATEMENT Click
This is shaping up to a bungle rivalling the cancelation of the Wolffdene dam and lack of understanding that it is "uncommon events" that fill our dams.
According to Minister McArdle and his Department "Discussion paper : shaping our water future" the discussion on the future leads to recycled water and desalination. Items we thought were not in the LNP policy. Not so, they the main thrust of their future.
In the working section there are no less than six illustrations of these two items that should not exist in a subtropical environment.
Three of these examples are
Page 12, Under the heading "empowering customers" reads "As demand for water increases, sources such as desalinated water recycled water and storm water need to be considered"
Page 14. The graph under the heading “the water cycle” reads “Adapted from recycled water in Australia ”. It includes “Recycled water plant” and “Desalination plant”
There they are shaping our water future. They are there because former Premier Bligh was correct on the demise of the Traveston Dam, the only storage of consequence attempted. "Look forward to a future of desalination and recycled water plus harsh water restrictions".
In a 30 year water plan there are no other alternatives of a scale to keep pace with rising water needs.
There are no applications that will eliminate flooding in Brisbane and mitigate flooding in Ipswich and Gympie.
The way forward
However, the integration of the Borumba dam expanded to a capacity larger than the joint capacity of the Wivenhoe/Somerset can resolve these matters
At a saving of $3.1 billion, we can flood proof Brisbane (thought impossible by Premier Newman and Lord Mayor Quirk), mitigate flooding in Ipswich with four of the last five floods kept below the damaging 14 metre mark, mitigate flooding in Gympie by damming the Borumba hard rock catchment which is within the Gympie catchment. Provide natural water to pass the much longer catchment periods than drought being 11 years
Progress with Seqwater in the examination of our plan.
On the 13th January 2013 the Courier/Sunday Mail published our plan in simplified form. It may be still held on line at the above link to the Courier Mail.
Even before we started they had this to say
“We seek to ensure infrastructure is not augmented before it is needed”. It seems a reasonable methodical approach. It is this approach that got us into big and costly trouble in the past and will do the same in the future if it is not recognized. (Seqwater initial letter) E.G. Prolonged drought known as "uncommon events" and flooding do not lend themselves to this approach in fact in recent times we have seen us damaged by several billion dollars.
This is the demand management instituted by Minister Casey on the cancellation of the Wolfdene Dam in 1990. It screwed up well laid plans for future use by this method by the dam cancellation. Our plan is to reinstall that dam with the expanded Borumba Dam.
They also declined to consider the Borumba expansion for at least another 6 years. Even then they said it would be subject to robust discussion. That dam expanded is central to the natural water needs of SEQ for the next 50 years.
So we see that even before we have reached the conference table they have laid down their positions which demonstrates to me that they have little grasp of how our water supply works and what additional benefits can accrue or they are reading off prior information. There were many editions of the prior "South East Queensland Water Strategy". This flows through to Minister McArdle and his advisors who draft his letters.
Our understanding at the meeting with Minister McArdle and Seqwater was that our plan would be examined "as it is" to see if it works and then for Seqwater to re-examine their position on integration. They have reversed this procedure with two major blocks exposed as briefly outlined above. The blocks are movable and should be removed.
We hold a reasonable financial hand in the development such as inclusion in the LNP national 100 dam plan. This was the result of our efforts. We have pointed out the error in the allocation of the Wivenhoe/Somerset water at a saving of $210 million annually. The damage caused by a large floods is in the $billions.
considered a "workshop". We consider that the plan's Hydrology has
been proven by events. Engineering of the project requires a one on one with a
Government engineer. Then a "workshop" could be of value.
Flood proofing Brisbane proven by the February 2013 flood
There was no flooding in Brisbane of any habitable premises (Lord Mayor Quirk).
There was no flooding in Ipswich. Mayor Paul Pisasale.
I seem to be the only one that was not surprised by the outcome.
The Wivenhoe Dam had sufficient room to hold back all water above the dam and as a consequence, we saw the effect of a full blown Bremer River and Lockyer Creek running free.
It is the foundation of this website, when viewing flooding, that the Bremer River and Lockyer Creek, on past information, does not have the volume to flood Brisbane and damage Ipswich. In Ipswich, most of the block caused by the Wivenhoe at the Bremer entrance is removed.
* To move direct to Flood Proofing Brisbane. Mitigation in Ipswich and Gympie. CLICK
A brief overview of our water supply
Since the completion of the Wivenhoe Dam in 1986, in the period 1986 to 2001 we witnessed the dam filling by 1988 and a further 4 refills in 1992, 1996, 1999 and a top-up in 2000. It takes "low pressure systems" to do this as recognized in this graph by its "factory roof type" in its dam levels. In that 12 years, we had plenty of water or so we thought.
Desalination : The Tugun plant would take 26 years to 2038 to fill the Wivenhoe dam if no water is taken out. 35 years to year 2047 if the Somerset is included.
Recycled water : Using reports of former Premier Bligh, recycled water is the same volume.
Between them they can only supply 31 per cent of our present requirements. This means very heavy water restrictions on reaching 40% level in our dams.
Much better way
Much better way: There is a much better way to eliminate flooding in Brisbane, mitigate flooding in Ipswich and Gympie, put real meaning into "drought" proofing Brisbane and reduce water price permanently. That is what this website is all about.
So we have seen it all in a practical way in our lifetime. However we have not learnt from this and the LNP appears to be following the same path.
Residents of South East Queensland deserve better than a second clumsy go at securing our water supply which will be again at a high cost.
Post Election/Flood Inquiry - period
With election out of the way and the final flood report tabled there are some clear issues emerging.
1. Our Wivenhoe/Somerset dams are too small to deal with the conundrum
of "Drought" and "Flood".
The current block to the system (point 6) that needs to be rectified. Points 8 to 13 cover point 6 Click hereto view these points
* What went wrong with our water supply?
Click for full index
What went wrong with our water supply?
What went wrong with our water supply that caused those in charge to miss-spend the best part of 7,000 million dollars for a third class system that will not do the job intended?
How could we not foresee from past experience the inevitability of extended "drought" like periods and major floods in South East Queensland?
He failed to realise what was happening around him was something other than a "drought" with consequences that can be much more severe than any drought. The natural and random occurrence of our main water supply has such a variation from top to bottom that on the opposite end it would have had Premier Beattie sitting in a small boat in the Jindalee area or other parts of flooded Brisbane five years later.
The bottom end is limited by the capacity of our dams whereas the top end is unlimited. A volume equivalent to two and one-half times the capacity of the Wivenhoe went over the dam wall in January 2011. We examine the random and extensive nature of our main water supply events in the next heading.
His successor Premier Bligh also displayed this lack of understanding. I warned her of it on the 18th January 2008 followed by a warning to then Water Minister Hinchliffe on the 23rd April 2009. The warning was the mathematical certainty that our dams would refill and overflow. Read more
Our water supply
person in South East Queensland now realises that our
dams are not filled by storms that provided only 3% in the last 6
months and not by General rain which provides only moderate fills, the
largest in the life of the Wivenhoe being 15.6% in the middle of so-called drought. One
can see the small bump in 2003/04 on this dam level chart. Read
The red lines on this dam level chart emphasise the clear
statement of Mr Rob Drury, dam controller, of SEQWater who pointed out in his
article in the Courier mail Feb 2007 that it took large events to fill these
large dams. He called them "uncommon events".
It confirms Dorothea McKellar's OBE poem of the early nineteen
hundreds that there is a big difference between
"rain" and "flooding rain". They show two things:
1. Ordinary summer rainfall and storms were inadequate for our needs from the starting point of the Wivenhoe Dam. It takes concentrated rain ("flooding rain") as 300mm in a few days is a flood capable of filling the dams from scratch whereas 3 months of 100m each month is just a trickle.
2. The "uncommon events do not come every year". They average 3.7 years with most below that average. This means that those above the average can extend for up to 11 years which is well beyond the longest known drought being the 5 year Federation drought 1898 to 1903. They are more prevalent than the chart indicates as many do not come west enough to cover the catchments.
The volumes that are supplied by "uncommon events"
vary from 20% to 285%. We have now all seen four of these "uncommon
events" refill the dams from 18%. Overflows then occurred with 26% in October 2011
followed by December with 24% and finally January with overflow of 285%.
Review of serious errors of judgment will give us further insight on how to deal with Flooding and putting real meaning into "drought proofing". This is not a political statement. It should be kept in mind that the dams were under the control of the Labor Party for the life of the Wivenhoe (1989-2012) of 23 years except for three years.
Serious errors of judgment
1. Kevin Rudd - Wolffdene Dam
Kevin Rudd - Wolffdene Dam
Wolffdene dam water supply
By 1992 it was obvious from the dam level chart of the Wivenhoe pictured on our right that our water supply could not survive without "uncommon events". Assurances were given at the time of cancellation (Planning had commenced) that further planning would be carried out. If planning was carried out it was entirely inadequate for "drought" and "flood". Read official parliamentary statement
Wolffdene dam in flood time
This 2011 flood saw all catchments saturated. There is no doubt that the Wolffdene dam would have been full well before the January 2011 flood. This would have permitted the pre-release of water from the Wivenhoe/Somerset sufficient to retain all the flood waters of the Wivenhoe/Somerset. With the Bremer River and Lockyer creek running free, there would have been little damage in Brisbane and Ipswich.
Premier Beattie and Deputy A. Bligh's "drought".
Premier Beattie used the "decile" map extensively to convince us that our low dam levels were caused by a "drought". Decile maps grade rainfall from 1 to 10 with "1" the "lowest on record" category. The corresponding map is a "percentage" map that records the percentage against the long term average 1961 to 1990.
The rainfall for the period was in decile "1" even though the rainfall was 80% of the long term average. This is because district 40 in which the dams reside is a stable area and in 6 year lots, (the length of the so-called drought) never had less than 80% of the long term average since records were kept. So we are dealing with a statistical aberration. 80% being in decile "1" was not normal but was held out by Beattie/Bligh to be normal and accompanied by an enormous advertising campaign to convince citizens of SEQ of drought in the catchments.
Bureau of Meteorology rainfall stations in the catchments show that for the summer periods 2001 to 2006, Wivenhoe had 99.1% of the long term average and Somerset 91.4%. The 20% reduction was entirely in the non-summer months that produce little inflow into the dams.
If Premier Bettie had held the "percentage" map aloft which read 80%, then people would have considered the matter more deeply and required more explanation and perhaps the right path forward.
Premier Beattie and Deputy A. Bligh. - The Traveston dam
For citizens of South East Queensland, the choice of the Traveston over an expanded Borumba Dam to a holding capacity more than the Wivenhoe/Somerset combined was a monumental and costly blunder.
The public guarantee of Ms Bligh to residents of Gympie
dealing with the Borumba that
"that would be the way they would go if it stacked up" was a sham. Ms
Bligh was writing to grazier Ron McMah to obtain commonality of the terms of
reference so that the Engineering and Hydrology reports could start. Those
Letter Bligh 31/01/07 : Signed Engineering 22/01/07 :
Beattie view ignored by Bligh
The most important feature of the McMah proposal was the storage of surplus water from the Wivenhoe/Somerset. The catchment of the Borumba was too small for for such a large dam and we needed more capacity.
Both the Engineers and Hydrologists reported that they had received "advice" that there was no water available from the Wivenhoe/Somerset. After meetings with Minister Hinchliffe and later senior members of DERM, I was provided by the Chief Hydrologist the information necessary to determine that there was available between 130,000ML and 160,000ML annually to us that had been diverted to the ecology by a clever, or alternatively clumsy, manipulation of a single definition. The instructions of the Technical Advisory Panel had not been followed
It explained to me why the "yield" of 446,900ML as publically
advised by the former SEQWater, not connected to the current Seqwater, being
reduced to 286,000ML, a drop of 160,000ML. (Yield is the volume of water that
can be guaranteed in a year without failure otherwise known as HYNF)
This volume of 160,000ML plus the additional yield from the expanded Borumba of a further 50,000ML is well above the 110,000ML Traveston proposed by Premier Beattie with the final stage of 40,000ML well into the future and ephemeral.
With the Traveston cancelled by the cross-check environmental concerns of the Federal Government that were not picked up by the QWC and the contractors, Premier Bligh declared that "desalination" was the only answer.
That decision was seriously deficient and we will examine.
1992 to 2001 Those in charge and the Flood Commission.
There was no panic or serious observation of how our water supply works in that period. However there is cause for concern when we apply their findings on dam reductions to counter flooding.
The Wivenhoe and Somerset dams were designed with flood compartments that exceed the FSL (drinking water compartments). The Commission recommends manipulation of these FSL volumes for flood mitigation benefit.
Application of the current 25% reduction in November 1995 would have seen the dam level fall to 19.7% (44.7 - 25.0) That level is comparable with the so-called "drought" period low in 2007 of 18.0%. Application of the 25% in that period would have seen a negative figure of -7.0%.
The dam controllers do not have the ability to allow the dam level to rise. They have to await a "low pressure" system to come along. They average 3.7 years since 1841. The dam level graph above tells the story.
There is currently not enough capacity in the dams to deal with this conundrum.
Queensland Climate Change Centre of Excellence
In my view this organisation has presented misleading information in the name of "Climate Change". They produced this document that has been picked up in the Queensland Water Commission Water Strategy and now by the Flood Inquiry in its interim report. There are fundamental major errors in it and it should be withdrawn.
They may be viewed in QCCCE
A review of carbon dioxide tax can also be viewed click
One example of predictions is by well known Mr Tim Flannery now chairman of the Federal Government Climate Change organisation. He was on the original Board of the QCCCE in 2007. As reported in the "Herald Sun" "In 2007, Flannery predicted cities such as Brisbane would never again have dam-filling rains, as global warming had caused "a 20 percent decrease in rainfall in some areas" etc."
The Herald goes on to say that premier Beattie took the prediction seriously leading to desalination.
The prediction was badly astray with serious consequences. Since 2007 the Major dams of Wivenhoe/Somerset not only filled to 100% capacity by March 2009, well before the La Nina weather pattern took hold, and then overfilled with the volume well above twice the Wivehoe Dam capacity going over the dam wall by January 2011.
In their scramble for authenticity they added a further two years to the "drought" being years 2008 and 2009. You will see the evidence that in those two years the catchments had rainfall of 125% of the long term average.
The QCCCE therefore had a two-pronged excuse for low dams of "drought" and "Climate change". Because these excuses were accepted, research into the underlying cause of depleted dams was blocked and, as a consequence, contributed to considerable damage from flooding in Brisbane and Ipswich.
It was also consequential in producing a water grid costing billions of dollars that is largely ineffectual.
* Borumba dam integration. Where is it and what does it
look like. Click
to go direct
Drought proofing Click
to go direct
Water share between the Ecology and residents of South East Qld. Click to go direct
Borumba Dam integration with Wivenhoe/Somerset: Where is it and what does it look like
This involves the integration of the Borumba Dam 40 Klm over the hill from the Somerset dam with the Wivenhoe/Somerset Dams. It has the dual purpose of backup supply enabling the Wivenhoe Dam to be permanently lowered and further lowered to be almost empty before a major flood. With two-way pumps capable of transfer rates 32 times the output of the Tugun desalination plant, normal water supply will be available during any "drought" period.
Click to view the location of the dam
CLICK HERE to view channel 10's review of this Dam. It includes an interview with local grazier Ron McMah. Trevor Herse, retired of the Gold Coast and myself were well aware of the huge water surpluses of the Wivenhoe/Somerset catchments from "low pressure systems". We coordinated with Ron who had identified the storage capacity for these surpluses in putting forward this proposal.
One will notice that the topography of the Dam with high hard rock walls makes it suitable to expand to a capacity larger than the Wivehoe/Somerset Dams as certified by engineers.
Overflows lost to our water supply
With the figures now confirmed a volume of
water equivalent to 229.5 percent of the capacity flowed over the dam wall in
January 2011. This is in addition to the 55.5 percent that had been released in
October 2010 to December 2010. That total of 285.0
percent was lost without a Megalitre being saved.
It gets worse, 25% of the Wivenhoe has now being released. This means that during the recent events we are 25% of the Wivenhoe capacity worse off than when it started.
The dams began filling in 2007 and have been full since March 2010. This date is well before the La Nina weather pattern took hold.
There was no reserve supply sufficient to permit early release of our FSL “drinking water” compartment to avoid damaging flooding. That water is regained at the back end of the flood.
Flows above and below the dams
Those who who would have believe that 50% of flood water comes from below the dams are badly astray. They rely on catchment areas without the application of rainfall statistics.
According to the Water Resource (Moreton)
Plan 2007 by their official IQQM computer model, the Wivenhoe/Somerset provides 56.5% of all
water that reaches the mouth of the
The temporary retention of "above dam" flood
waters clears the way for the
This set of numbers following was published by Engineers GHD in December 2011. It was based on Seqwater Historical Flood Events Hydrographs. The 1893a flood had only 23.82 percent of the flood below the dams coming from the main tributaries. Similarly the 2011 flood had only 34.94 per cent below the dam. I have placed the 1974 above dam total in red and I refer to my official supporting information. It indicated the 1974 above dam flood is 2,200,000ML based on official supporting documents. This reduces the below dam percentage to 42.0 percent.
Nevertheless the GHD figures supplied by Seqwater indicate that the 2011 flood had a volume above the dams of 138% more than the 1974 flood. This is a major departure from Seqwater claim of 190% in their much criticised document lodged with the Flood Inquiry.
When viewed with the the 50% catchment area above, it does not give one confidence in the rest of the document.
The essential element to flood proofing Brisbane is to know the inflows that occurred since records were kept from 1890 to 2010. This is to determine the flood with the largest inflow volume in the Wivenhoe/Somerset catchments. It is that flood that we must contain.
If we are successful in retaining the largest recorded flood then 58% of the entire flood is taken out of the equation and released without harm at the back end of the flood. It is the peak that does the damage. The 58% is calculated by the IQQM computer model that has the force of Law in calculating the 66% required for the Ecology.
This permits the
Reported flood volumes
Seqwater and Brisbane City Council reports have similar volumes and obviously are reading from the same gauges.
The reported flood volumes
If accepted, then 1893 at 2,744,000ML is the largest flood that we have to deal with and nothing further needs to be examined. We will see that this volume is capable of being withheld with room to spare. ( GHD report of December 2011 records it at 2,799,234ML)
My review of flood volumes can be examined in the Flood Review tab.
The review suggests to me that a volume of 3,000,000ML will cover all contingencies.
If further examination is sought click FLOOD VOLUMES
How has the Wivenhoe Dam performed since installation in 1985?
The floods of note are 1999 and 2011.
The 2011 flood is under close scrutiny of the Flood commission. The decisions made at flood time are most likely to subject to legal challenge well into the future.
The 1999 flood was on normal and not saturated catchments. The Wivenhoe was at 74.5% of capacity at the start and 135.1% at the end. The Somerset was 44.6% of capacity at the start and 154.2% at the end.
Seqwater placed the flood volume at 1,220,000ML or about 51% of the revised volume for 2011 of 2,380,396ML. That volume for 2011 included 540,000ML for a small flood not fully released early which is the nub of legal argument.
Review of Bremer River and Lockyer Creek
The submission lodged by the Ipswich Council provided some some insight into how floods affect that City. Three of those points are:
1. Damage begins to occur once the flood height at the railway
bridge reaches 14 metres.
There were 4 floods in recorded history that passed the 14 metre mark. They were 1893 Feb 24.5m; 1974 Jan 20.7m; 2011 Jan 19.25m and 1931 Feb 15.47m.
Lockyer Creek produced more volume of water than the Bremer River in all floods.
An example of the pressure of backwater is in 1974 the Bremer flow was 631,195ML whereas the 1893 flood had a flow of 196,825ML which is less than 1/3 of the 1974 flow. Yet the Bremer River Height was 24.50m in 1893 compared to 20.70m in 1974.
Above left are the Seqwater flows 1893, 1974, 2011 Right picture is 1931 rainfall
The hydrological analysis of Ipswich in the 2011 flood had the one mile bridge at 6 metres above due to backwater.
On that basis, the 1893 and 2011 floods would have been kept below the damaging 14 metre mark.
However, the 1974 flood at 20.70m had to reduce by 6.70m to avoid damage. The rainfall and resulting flows were much higher than ever experienced. My Ipswich correspondents, having experienced the flood, say that may not be the case. Hydrological and hydraulics reports will be necessary.
Review of the 1931 rainfall is enclosed. Withholding of the Wivenhoe/Somerset will reduce it from 19.25m to below the 14.00m mark.
Logic of flood mitigation in Brisbane
* The highest flood volumes from the Wivenhoe/Somerset is 1893 which this website explains can be contained until after the flood.
* There is a caveat on the 1974 flows for the Wivenhoe/Somerset as the pre-development flows of DERM and the rainfall stations information both conflict with Seqwater volumes. The indications are that the percentage above the dams is in line with the DERM information of 58% average above Mt Crosby over 110 years.
* With the Wivenhoe/Somerset held, the waters of the Lockyer and Bremer run free.
* We know that the 1893, 1913, 1974 and 2011 floods should be below the damaging 14 metre mark in Ipswich with a caveat on 1974.
* A similar pattern should show up in Brisbane.
Flood mitigation in Gympie
The Borumba Dam stands on Yabba Creek. It is researched throughout this website as it was the subject of our submission to replace the proposed Traveston dam.
My calculations for the 1999 flood is that Yabba Creek provided 34.8% of the total flow through Gympie. To review click on Hydrology Mary Valley
As we will see later on this page, the major part of this proposal is the expansion of that dam from the current 45,000ML to 2,000,000ML. It will provide ample opportunity to mitigate flooding in Gympie to the extent of 34.8% of the flood.
Yabba Creek in full flood 2011(Gympie times photo)
1841 and prior
The Queensland Parliament at the time of the 1893 floods recorded that the 1841 flood was 7 inches (.2 of a metre) above the 1893(1) flood. The archaeological find at Indooroopilly, being up river, may well come in under the 1893(1) flood because up river heights are much higher.
For those who appreciate an easier read than the language of
this accountant, click on Trevor
Herse for his "Water woes result from misunderstanding and blunders". Trevor and I,
together with Ron McMah, grazier, of Imbil, have worked together on this project since 2006. We
represent no one and have in mind only the interests of citizens of South East
The containment of a flood to 3,000,000ML is the target.
How to deal with major floods
1. Saturation rain
Saturation rain preceded all of the floods under review. It is certain that the FSL “drinking water” compartments were, or would have been, full.
The official flood compartment volumes are Wivenhoe 1,450,000ML and Somerset 524,000ML for a total of 1,974,000. This represents 170 % as a percentage of the Wivenhoe capacity for easy measurement. Mr Ian Chalmers, the chief supervising engineer in the construction of the Wivenhoe has suggested in his submission the relocation of the fuse plugs to maintain these volumes.
FSL or commonly
known as “drinking water” compartments
These compartments are not normally reduced as the metrological events that fill them come on average every 3.7 years. Their fill usually represents 95% of the water in the dams.
Click to view official dam statistics Wivenhoe/Somerset
These compartments measure Wivenhoe 1,165,000ML and Somerset 380,000ML. The total is 1,545,000ML. This total represents 132 per cent of the Wivenhoe capacity.
to retain floods if all the compartments are available.
The flood compartments total 1,974,000ML or 170 %. The FSL or “drinking water” compartments total 1,545,000ML or 132%. The combination is 3,519,000ML or 302%.
The largest flood of 3,000,000ML represents 258% of the Wivenhoe Dam FSL. This can be held by the flood compartments of 1,974,000 plus the FSL of the wivenhoe at 1,165,000ML which totals 3,139,000ML or 270% of the Wivenhoe capacity. The Somerset FSL is not needed.
How does this work?
There is always the quandary “will flooding rains come or will they not?”
Our weather forecaster are becoming more reliable in predicting major events in our weather patterns. This article written by Brian Williams of the Courier appeared in their paper on the 1st October 2010. He points out that all dams are full and the weather patterns that produce flooding rains were entrenched. I have observed that throughout the flood period Brian Williams was accurate in reporting all events of the flood and that his reports could be relied upon.
It is necessary to early release the FSL “drinking water” compartments with the recent Bligh/Robertson decision in progress (28/02/11). As events unfold and the flood is reasonably certain, further releases from these compartments should be made at the front of the flood thus allowing the Bremer River, Lockyer Creek and the Brisbane River to run free.
This avoids the backwater and congestion of the Wivenhoe/Somerset releases. The extent of the early release will depend on the Meteorologists and their telemetry equipment.
It is a considered gamble on weather predictions.
If the rains do not come then you lose heavily as you have released your precious drinking water with almost no chance of recovery until the next “uncommon event”.
If the flooding rains come, you win well. Not only have you assisted in reducing damaging flood levels by taking the water from the Wivenhoe/Somerset out of play but most, if not all of the water released, can be recovered at the back of the flood.
How do you cover your gamble if it does not pay off?
This is an example of a
feeble attempt but a step in the right direction
Minister Robertson supported by Premier Bligh made the decision to release 25% of the capacity of the Wivenhoe dam’s “drinking water”. The backup explained by the Premier was the Wyaralong Dam which represents 6% of the Wivenhoe capacity.
The additional backup is the Tugun desalination plant and the recycled water that a lot of people dislike. The Tugun plant takes 34 years to fill the Wivenhoe/Somerset dams from scratch if we do not take water out. The recycled water takes a bit longer.
The consequence is that we will be out of water in 3 to 4 years if an “uncommon event” does not appear in the normal average of 3.7 years. It is a very high price to pay for such a small gamble on the weather. The Wivenhoe dam level chart with red lines shows that we rely almost entirely on "uncommon events" to refill our dams.
Click to view "uncommon events" in the Wivenhoe dam 1988-2007
When one exceeded the average in 2001-2007 it was misrepresented as a "drought".
obvious major reserve supply
The reserve supply needs to be in place permanently. The decision making process on release will depend on the concentration of the rain and will determine how much is released without the flood event happening.
It is most likely that no more than 60% of the Wivenhoe capacity would be released without the flood event occurring. This volume is 700,000ML. It is stored for later return if needed by the Wivenhoe/Somerset system.
A proposal to maintain a significant percentage permanently in the Borumba Dam and have a corresponding permanent reduction of the FSL- "our drinking water" has merit. It will give the dam operators more flexibility to early release.
This is well within the storage capacity of the Borumba Dam expanded to 2,000,000ML. This capacity is larger than the Wivenhoe/Somerset dams total capacity.
Borumba Dam - a brief resume
The dam already exists
It is a hard rock natural amphitheatre ideal for minimal evaporation.
Has its own small but efficient catchment.
1,500,000 for storage and 500,000ML for the Mary
of the Mary Valley from its damaged state which resulted from the scrapping of
the Traveston Dam proposal.
Borumba Dam proposal and appendix on cancellation of Traveston Dam
The Traveston is now historical but the alert to Minister Hinchcliffe and the use of the Borumba Dam as its replacement is still valid. These two proposal and appendix were submitted to the Queensland Water Commission when they were called for after the cancellation of the Traveston Dam. This procedure eliminates the planned three desalination plants and avoids most of the construction and ongoing costs. Further reading Borumba Dam Proposal and Borumba Dam Appendix
Drought proofing SEQ.
1. Drought in the catchments. Conclusive proof that there was no hydrological drought in the catchments
Former Premier Beattie, Premier Bligh and now Minister Robertson claim that South East Queensland is "drought proofed".
This section provides a different view suggesting that this phrase is misused to justify an expense in the region of $9 billion according to Mr Kim Wood CEO of Allconnex water (Refer WATER COST). An expensive cost brought about by those who should have displayed more diligence in the control of our water supplies.
This phrase "drought proofing" belongs with the "worst drought in 100 years" when related to the low levels of water in our dams. The evidence presented in this section is that while there was drought in most parts of the State, there was no drought in the catchments.
I have overlaid the Wivenhoe dam level graph with "uncommon events" as described by Mr Drury of SEQWater in the header above. The dam decline from each refill is marked in red.
That decline was obvious soon after the Wolffdene dam was cancelled for political reason in 1989. By 1992 it was obvious that normal "summer rain" was inadequate for our needs and we relied heavily on these "uncommon events". A longer period beyond their 3.7 year average would, and did, bring us grief with no provision by those in charge.
Click to view "uncommon events" in the Wivenhoe Dam 1988-2007
A convenient statistical aberration of a "decile" map was used to avoid scrutiny. The "decile" map was showing "lowest on record" for the rainfall, while the corresponding "percentage" map read 80% of the long term average. This can be viewed at DECISION MAKERS
The Bureau of Meteorology rainfall stations in the catchments were at the same time showing 99.1% for the Wivenhoe and 91.4% for the Somerset for summer rainfall December to March. Viewed at the bottom of the RAINFALL DEFICIENCY page.
A further example of timing of "uncommon events" is this comparison. With a time period of 3 years and 9 months, the February 1992 to November 1995 was right on average of 3.7 years. The dam level dropped from 100% to 44.3%. Bureau of Meteorology maps show that there was no drought in that period with rainfall 90% to 100% of the long term average. Click to view comparison
Comparing the same 3 years and 9 months period of the "drought" February 2001 to November 2004, the level dropped from 100% to 53.4%. We held 9.1% more in reserve than in a period with no drought.
It is now certain that there was no drought in the catchments for the 2001 to 2007 period. It was simply the operation of low pressure systems. The 2001/07 period was an object lesson in how the 3.7 average works. Most are below that average so the few that are above can be quite lengthy.
More recently there have been attempts to extend the "drought" to years 2008 and 2009. I have forwarded to the Qld Flood Inquiry the Bureau of Meteorology Rainfall graphs for those years which show the rainfall in the catchments 125% of the long term average.
Premier Bligh and Minister Hinchcliffe were warned of this mathematical certainty that Low Pressure Systems would return and overfill our dams.. Click to move to these warnings.
The importance of this is that forward planning by the Queensland Water Commission in its strategy for SEQ is related to preparing for a "drought".
Our main water supply is low pressure systems. They are random and can occur at any time of the year and for much longer than any "drought". They are oblivious to the conditions prevailing at the time.
2. It requires a different approach to drought proofing.
It requires a different approach from the present stance of "drought proofing" SEQ.
The current claim of "drought proofing SEQ" is in the same category as "worst drought in 100 years". They both do not stand up to scrutiny by a long way.
The current "drought proofing" relies on the Desalination plant at Tugun which can produce 45,000ML a year. The recycled water produces almost the same based on Premier Bligh's most recent comments.
Seqwater spokesman advised that the current release of 25% was one year's "drinking water". That is 291,000ML a year. The official "allocations" made from the Wivenhoe/Somerset dams are 286,000ML so the spokesman is near the mark. Deduct the 90,000ML from Desalination and recycled water and we have a shortfall of 200,000ML each year for the length of the "drought".
the other hand the two-way pumps between the Wivenhoe and Borumba Dams can have transfer rates of up to 4,000ML per day compared to using the expanded Borumba Dam
storage of the Wivenhoe/Somerset water for later return
the other hand the two-way pumps between the Wivenhoe and Borumba Dams can have transfer rates of up to 4,000ML per day compared to using the expanded Borumba Dam
storage of the Wivenhoe/Somerset water for later return
objective is to maintain the wivenhoe/Somerset dams above 40% level before recycled
water is introduced. This is on the basis of a yield of 373,000ML which is
considerably higher than the 286,000ML presently allocated.
On the past history of 120 years, it would require no more than 500,000ML to be retrieved from the Borumba Dam for a period of three to four years at the bottom of the drought cycle. It would have happened only twice in those 120 years.
Pumping to the expanded Borumba Dam would be undertaken when dam levels are high creating space in the Wivenhoe/Somerset dams to capture as much as half of the 55.5 per cent overflow created in October/December 2010.
have costed the dam wall to $1,397 million. It includes a hydro plant. Add to
that an engineers estimate for the pipes and pumps of $500 million and deduct
the unknown cost of the Water Commission dam wall to 350,000ML and we have a
cost equivalent of one desalination plant of the Tugun size.
to the high cost desalination, the operating costs are minimal. The spare
capacity can be filled over a number of years with little draw down required.
The Hydro Plant will be operating full time as water is already used by the
Gympie and district people.
The proposed three desalination plants will not be required.
In essence the well credential Technical Advisory Panel who examined this allocation recommend that 66% of all water that passes through the Wivenhoe/Somerset dams must reach the Brisbane River mouth. It is now the law (March 2007). I have no problem with that percentage.
However in the writing of the Act the Technical Advisory Panel's advice, that large floods should not be included when calculating the permanent base on which the 66% is calculated, was ignored.
The base on which it was calculated included the four major floods of 1890, 1893 (two) and 1974. The result is that when applied against the 113 years 1894 to 2006 (excluding 1974) the percentage rises to 78%. It cannot be disputed, it is straight forward simple arithmetic. Readers will have no difficulty understanding this when they view the official chart of inflows into the dams for 1890 to 2000 on the "water share" page.
The effective result is that a volume of water equivalent to the proposed, and now cancelled, Traveston dam is redirected from our consumption to the ecology every year. That is 160,000 ML.
In today's terms the massive infrastructure of the Wivenhoe/Somerset Dams, which cost $550 million, would equate to a cost more than $1 billion. It has been reduced from SEQWater's public records of 446,950ML annual yield to allocations of just 286,000ML by the introduction of this Law in March 2007. The fundamental arithmetic flaws need to be corrected. (A yield is the volume that a dam can produce in a year without running dry. It is calculated in this case over 111 years).
While this fundamental arithmetic flaw exists, the Water Strategy for South East Queensland is severely affected and will involve major costs on the drawing board that are not necessary.
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