AN OBSERVATION OF THE CONFLUENCE OF STATISTICAL ABERRATIONS, DAM RATIOS, TIMING AND UNCOMMON RAINFALL EVENTS THAT COMBINED TO PRESENT OUR DAMS AS VICTIMS OF A SEVERE DROUGHT. THIS IS NOT THE CASE. THEIR INFLUENCE ON CONCLUSIONS REACHED AND ACTIONS TAKEN.

Author : J. V. Hodgkinson F. C. A. Chartered Accountant : August 2006 to December 2009

The Underlying cause of our depleted dams had the appearance of "drought". However most people would not class 80 percent of rainfall compared with the Bureau of Meteorology long term average 1961 to 1990 as a "drought". This is the case in the catchments. Even less people would class it as a "drought" when closer examination of the rainfall shows that the inflow producing four Summer months had been quite normal with 99.7% in the Wivenhoe and 91.3% in the Somerset catchments. The 20% deficiency was in the low inflow producing eight non-summer months.

This incorrect conclusion of "drought" has clouded the real underlying cause of our depleted dams. It is the random nature of large scale rain depressions and they are our main water supply. They occur on average every 4 years and have the capacity to fill our dams in a few days. The last gap was six years 2001 to 2007 and caused a major and expensive panic. Further evidence is available in the tab DEPLETED DAMS or Click here

Dealing with those large scale events that extend beyond the 4 year average requires a very different approach than dealing with a "drought". The current water resource strategy has ignored the short history of the Wivenhoe dam.

Click the photos to expand. The back button to return

The Traveston Dam has been cancelled and all reference to it is being, or has been,  withdrawn from Government web-sites.

One may draw the conclusion, based on this evidence, that it was never an option in dealing with the temporary absence of our main water supply, being large scale rain depressions. It is examined later.

These two articles from the Gympie Times of the 24th and 26th December 2009 are reprinted with permission and without comment. They represent the Gympie Regional Council view of the Traveston proposal and the way forward post-Traveston. Of particular interest is their main reconstruction view being a new dam wall at the Borumba Dam.

Photos : Gympie times articles by Arthur Gorrie. Reprinted with permission and without comment.

In addition the Queensland Water Commission (QWC), at a most senior level, has drawn my attention to the South East Queensland Water Strategy (SEQWS) section 5.4.2. The main aspect of that section is the raising of the Borumba Dam wall and is the only matter contained in that section that has relevance to our proposal. We have drawn upon the consultancy report mentioned which included a dam wall to 1,650,000ML with two saddle dams and hydro power and built in three stages at a costing of $1.4 billion. Our proposal is a 2,000,000ML dam with the same facilities but built in one stage. 

The Mary Valley people agree that the 84% requirement at the Mary River mouth is almost all flood water and, in our view, should be reconsidered in the light of greater control and the damaging effect that flood waters had on Moreton Bay. It is contained in the recent committee report headed by Vice Chancellor of the University of Queensland, Professor Paul Greenfield and outlined in the Courier Mail. An EIS is required and this will enable a review of the Water Resource plan governing it.

Both of these proposals do not fully represent our proposal. Their main interest in the Borumba dam is containment of further waters from its small catchment requiring a dam of a capacity in the vicinity of 500,000ML or less. Our view exceeds that by increasing the capacity of this last remaining natural amphitheatre to the 2,000,000ML. With the use of a two-way pipeline, coupling it with the Wivenhoe/Somerset dams with a storage capacity of 1,545,000ML thereby doubling the storage capacity. 

The net effect is 52,000ML additional from the expanded Borumba. Release of 93,000ML now held in reserve in the Wivenhoe/Somerset mainly for "drought" contingencies and the examination of the further 80,000ML identified by engineers GHD when raising the Wivenhoe dam wall was considered. An all-up total of 225,000ML By way of comparison the ill-fated Traveston proposal, all three stages to 2050, was 150,000ML.

The first 52,000ML requires an EIS. As there is a dam already there and it was part of the failed Traveston, the problems should be minimal. The release of 93,000ML has no legal impediment from the Water Resource (Moreton) Plan. The remaining  80,000ML will require an EIS as Moreton Bay and the Water Resource plan is involved. This will give us a complete picture of the decisions made and how the requirements of our Citizens and the Ecology were balanced in that Water Resource Plan.

The  QWC has confirmed some aspects of past history of the Wivenhoe/Somerset. This has permitted a clearer view of how the mechanics could work and how it compares with available and proposed options such as desalination and the injection of recycled water. It will show that the expanded Borumba dam is a far superior option to desalination and recycled water. This is now contained in the APPENDIX attached to the "Borumba dam proposal alternative" which follows.

Click on appendix to view and "return to" button to return to this position.

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A short overview may be helpful before moving on to the "Borumba Dam expansion alternative" below. 

This chart showing annualised inflow and "years to fill" calculations will give one a perspective on the relevance of each source of our water supply. 

While scrapping the Traveston Dam project was an integral part of our plan, the underlying root cause of our water shortage is still not addressed and, on its present course, will lead to costly desalination plants that will not replace the water from large scale rainfall events. They measure 417,567 Megalitres (ML) on an annualised basis. Calculations by the relevant Government Departments indicates that it is much higher flow through the Wivenhoe/Somerset system. For further information, click on Brisbane River 66% tab and Additional Reading tab

Photo : Our available water sources with the Traveston left in for comparison

Our other main water supply is Summer Rainfall which we now know so well. It measures 193,125ML annually. As an example, Summer Rainfall in year 2004 measured 242,131ML based on dam level charts and Bureau rainfall data. It was above average. The dam level fell only 2.1 per cent for the year to June 2004 without any water restrictions in place. Summer rainfall rectifies its average every three to four years. For further reading Rainfall 2001-2006 and Wivenhoe Dam.

Large scale rainfall depressions are know by SEQWater as "uncommon events". They were identified by them in the Courier mail of the 10th February 2007 as requiring 300 to 400mm over the whole of catchments. They are not easily recognized in overall rainfall statistics as 3 months of 100mm per month is just a trickle into the dams whereas the former can fill the dams from scratch to overflow in a few days.
Photo : Courier Mail article quoting SEQWater on our water supplies.

The attached "frequency of large scale events" has been compiled by me from Bureau of Meteorology records and their flood information to cross check for accuracy. It records the average gap in years in pink and the years beyond that average in blue.

It is the years with a blue graph that exceed the 4 year average. One can see at a glance that there are seven "gaps" longer than 6 years just experienced. Our hydrologists of that time had experienced the longest gap of 14 years. They commenced the Wolfdene dam after the Wivenhoe was completed knowing full well the consequences of a very long gap. For further reading click the Wolfdene Dam tab.
Photo : All large scale rainfall events dating back to 1841with below average and above average gaps due to their random nature.

The impact of the comparatively short span of 6 years is shown on this Wivenhoe Dam level graph. Just two years over the average. It was completely misread as the "worst drought". This graph produced by SEQWater does not appear anywhere else. It was specifically drawn to match the Courier Mail article but was not published.

Photo : Wivenhoe dam level chart which, when read in conjunction with the "frequency" chart above shows that the 6 year gap was predictable and misunderstood when it arrived.

A click on the Decision Makers tab reveals that the last 6 year gap, while it created panic, was nothing out of the ordinary and certainly did not deserve the tag "worst drought in 100 years". The "Decile" map used to justify it was a statistical aberration as there had been no rainfall in the catchments below 80% of the long term average since records were kept.

End of overview ************************************

The use of the Borumba dam expanded to 2 million megalitres is now the major direction of this website. The website's original material is retained where relevant as there are many points that are referenced by this website and its readers. It is referenced under Additional reading.

A companion to "Borumba dam expansion alternative" is "What happened in our catchments to deplete our dams?". While the depleted dams had the appearance of a severe drought, this was not the case based on the evidence. It is central to our solution and diametrically opposed to the Queensland Water Commission's view and solution. It can be viewed in the tab DEPLETED DAMS Click here

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BORUMBA  DAM  EXPANSION ALTERNATIVE  
Appendix attached

·       Recognize the actual cause of our recent water crisis and implement a permanent solution.

·       Expand the capacity of the existing Borumba Dam utilizing the natural features adjacent to the existing Dam wall thus creating the largest Dam in South East Queensland as our major reservoir.

·       Include hydro-electric power plant in Borumba Dam design to contribute towards power requirements for pumping between Dams.

·       Connect Borumba to the Wivenhoe\Somerset Dam System and the South East Queensland Water Grid.

·       Manage water between Dams as required to avoid flood water loss and provide adequate supply.

·       Increase natural water supply for South East Queensland without the requirements of desalination plants.

·        Drought proof South East Queensland well into the future, provide certainty to the Brisbane River ecology requirements, and reduce potential flood damage in Grid Area and Moreton Bay.

Attachments that support this document can be viewed on our website where an exact copy is located. www.WivenhoeSomersetRainfall.com  Click the tab 

Ron McMah   Imbil
Trevor Herse   Gold Coast
John Hodgkinson    Brisbane    hodgkin@powerup.com.au

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“Worst Drought” declaration of depleted dams was fundamentally flawed. As a consequence, solutions proposed were fundamentally flawed

With the Traveston Dam now eliminated the current perceived “disarray” in our water supply system still has its roots in the recent depletion of our Dams being erroneously attributed to “the worst drought in 100 years”.

That phrase applied to our recent water shortage in our dams, on the basis of official evidence, is a fundamental error. This, in turn, caused the major proposed solutions of the Traveston Dam and now ultimately additional Desalination plants, to be diametrically opposed to a workable and viable solution.

A review of the most recent pronouncements has revealed that History is repeating itself. The lack of understanding of the operation of the Wivenhoe dam and its interrelation with our two main rainfall sources is again showing itself. It previously led to the cancellation of the Wolfdene dam and the warning signs of dam failure, evident in dam levels since 1992, being ignored with no explanation offered. 

It took 15 years to acknowledge that the cancellation of Wolfdene Dam was an error. “Large scale rainfall events” described by SEQWater as “uncommon events” are our main water supply but are random occurring, on average, every 3.7 years. The last gap of 6 years, 2001 to 2007 was enough to send us into a panic and blame their absence on the flimsy evidence of a decile map. Decile maps are prone to statistical aberrations in stable rainfall areas such as our catchments.

There was no drought in the catchments unless one believes that 80% of the long term average is a drought. The 20% deficiency was in the non-summer months that rarely produce inflow. The appearance in the lowest decile being the “lowest on record” was because there had never been a six year period that was less than close to 80% of the long term average, 1961 to 1990, since records were kept. These Bureau of Meteorology records date back to the 19^th century. This is despite a large part of Queensland being correctly drought declared at that time.

The action that we must now take is critical to future generations to avoid a repeat of that panic. Based on past history the gaps in these events can last up to 14 years. Desalination plants are to be introduced to provide for increasing population. It takes a desalination plant the size of Tugun 34 years to fill our dams if no water is taken out. They are pop-guns in attempting to match “large scale rainfall events” that can fill our dams from scratch in a few days.

The proponents of “climate change” should take heed. The “large scale rainfall events” are said to increase in size. More importantly, the random gaps will be longer.

If this it is understood, significant control of rainfall from these events can be achieved by coupling the existing Wivenhoe/Somerset dam system to an expanded Borumba dam thus doubling the storage capacity in South East Queensland. The “disarray” can be cleared up and the end product made into the World Class Model envisaged by our Leaders.

Because of the complex nature of this subject and the need to backup up all statements with official supporting documentation, I created a web-site for the benefit of my friends. It has come into general use.

My web-site’s official statistics now record over 32,000 separate computers accessing the web-site including many Government Departments, Interstate and Overseas visitors. They are all very welcome but it is their responsibility to assess the evidence.  Over 70% have added it to their favourites.

In the end the solution appears quite straight forward and almost simple.

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SUMMARY OF THE SOLUTION

Action

Benefits

Costs

Timing

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INDEX
Click on the headings for the related topics outlined in that section.

Our catchments rainfall

1.1 Types of rainfall
1.2 Summer rainfall
1.3 Large scale rainfall events

“Large scale rainfall events” are our main water supply. Their random nature is at the heart of the problem

2.1 Historical occurrence
2.2 Mathematics of these events
2.3 Observed in the Wivenhoe
2.4 Recent large gap
2.5 Wivenhoe experience

The “worst drought in 100 years” re-examined

3.1 Summer rainfall normal compared to long term average
3.2 Deficiency of 20% confined to low water producing non-summer months
3.3 Population showed no sudden increase
3.4 Large scale rainfall events missing
3.5 Gap 6 years in large scale rainfall events. Water reserves rescued by 4 near misses.
 

Solutions – “Drought proofing” method to counter “worst drought in 100  years”.
How do they stand up to a 14 year drought without our main water supply.

4.1 Some good solutions
4.2 Traveston Dam
4.3 Desalinated water
 

Solution - Alternative solution based on the knowledge that recent depletion of our dams was caused by the random nature of “large scale rainfall events”
How do they provide for the absence of our main water supply for 14 years.

5.1 General outline statement
5.2 Raising the Borumba dam wall to 2 million ML plus Hydro.
5.3 Managing dam levels
5.4 Spare water storage
5.5 Review and revise “Water Resource (Moreton) Plan 2007” (WRP) to cover changed storage conditions.
5.6 Degradation of water quality in Moreton Bay minimized
5.7 Allocation of the final 80,000ML, now held in reserve in the Wivenhoe/Somerset moved permanently to Borumba.
5.8 Summary of additional water available without any conditions
5.9 Additional water available
5.10 Calculating the volume of water that has to flows through the Wivenhoe/Somerset for the WRP
5.11 Accommodation of the 80,000ML identified by engineers GHD

6.0 The facts at our disposal

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ASSESSMENT OF THE CAUSE OF OUR DEPLETED DAMS AND THE SOLUTIONS PROPOSED

Our catchments rainfall

1.1 Types of rainfall and their impact on inflows into the Dams

SEQWater was very clear in the Courier Mail article of the 10^th February 2007 that there are two types of rainfall that create the major flows in the catchments. The official evidence supports their statements.

Photo : Courier mail Feb 07 types of rainfall

1.2 The first is summer rainfall covering the four months December to March. They have provided 54% of all rainfall ever since records were kept. Official records indicate that it would take 7 to 9 years for this type of rainfall to fill the dams if no water is withdrawn. Summer rainfall is now well known to us all.

1.3 The second is “large scale rainfall events” that occur over a few days being Monsoons, Cyclones and Rain depressions. They generally cover all of South East Queensland. They have the capacity to fill the dams in a few days. They ignore completely the time of year. The main catchments require 300 to 400mm in those few days. SEQWater describe them as “uncommon events”. They are in fact quite common occurring on average every 3.7 years using Bureau of Meteorology data and flood heights.  I have replaced their term with “large scale rainfall events”.

300mm in a few days produces a flood whereas 300mm over 3 months at 100mm a month creates a trickle. They have the ability to disguise themselves in official statistics. One half of the 20^th Century in 6 year lots had almost the same rainfall as this 6 year period of “drought”, 2001 to 2007.  Without a large scale rainfall event in any of them they would have all produced the same “drought”. The current period was not unique but this fact remained undetected.

Photo : Rainfall in 6 year lots. Those on left have no large scale rainfall events

We will find that “large scale rainfall events” are our major water supply but are random in their nature with little reliability in timing.

Click to go back to index  

Photo : contributors to our water supply

“Large scale rainfall events” are our main water supply. Their random nature is at the heart of the problem

2.1 Official records dating back to 1841 show that large scale rainfall events occur on average every 3.7 years with 43 on record. This is based on official rainfall statistics and backed up by flood heights at Brisbane City and other Bureau recorded information. Most occur within 4 years.

Photo : "large scale rainfall events" covering 1841 to 2006. Large gaps in years identified in blue

2.2 It is a mathematical certainty that if most occur within 4 years then those above 4 years will be fewer but stretch well into the future. It is the events that can occur past the 4 year mark that interest us and created the current problem. Past records show that they can have gaps of up to 14 years. The blue gaps represent those that exceed the 4 year average. Note that the last 6 year gap 2001 to 2007 caused considerable panic and cost.

2.3 They are observable in the short life of the Wivenhoe commissioned in 1986. The dam was filled to overflow in April 1988 and April 1989 causing the acknowledged error of cancellation of the Wolfdene dam, construction of which had yet to be started. The then recently completed Wivenhoe was full. However it fell to 70% by 1992. That should have alerted us to the fact that summer rainfall was inadequate as far back as 1992.

Photo : Wivenhoe dam level graph overlaid by large scale rainfall events.

2.4 The Hydrologists of that generation, having experienced a large gap of 14 years (1974 to 1987) without “large scale rainfall events”, knew full well that Summer Rainfall was inadequate. Reading of the Courier mail indicates the hydrologists of that time were world class with international experience.

2.5 The Wivenhoe was refilled from levels as low as 47% a further 4 times, three to overflow. The dam level graph, which has not been published, records the constant depletion through the inadequacy of summer rainfall even though rainfall received then matched the long term average. That graph is attached for convenience of the reader. All other documentation is contained in the website.

Click to go back to index  

The “worst drought in 100 years” re-examined

3.1 Official statistics are listed at the head of every page in the web-site which show that summer rainfall in the Wivenhoe catchment was 99.7% of the long-term average for the period of the “worst drought” being 2001 to 2006. It was 91.3% in the Somerset catchment.

Photos : Bureau rainfall data for Wivenhoe and Somerset catchments from 1964 to 2006

5.7 Of the yield in the Wivenhoe/Somerset established by the Government of 360,000ML, 80,000ML is not allocated for consumption apparently because of unforeseen “drought” possibilities. This can be released with the Borumba backup. (Yield is the amount that can be drawn from a dam using past rainfall statistics without the dam failing and is known as HYNF)

5.8 So without any restrictions or complications, 132,000ML is available which is almost the size of the proposed Traveston all three stages. (52,000ML additional yield from expanded Borumba connected to Wivenhoe + 80,000ML unallocated in the Wivenhoe/Somerset).

5.9 There is a further 80,000ML identified by engineers GHD when they considered raising the Wivenhoe dam wall. However, if the calculations of those who prepared the Water Resource (Moreton) Plan of 2007 are correct then there is much more water to consider. For example: 5.10

Photo : Engineers GHD calculation of additional water available if Wivenhoe dam raised.

5.10 Calculating the annual volume of water through the Wivenhoe/Somerset using the Government yield information and the requirement of the Water Resource (Moreton) Plan 2007(WRP).

The yield available for our use or held in reserve is 360,000ML annually.

The WRP requires 66% for the Brisbane River mouth that leaves 34% of all water that passes through the system for us.

Therefore the volume of water that must pass through the system each year to comply with that Act is 1,058,823ML (360,000ML divide by 34% X 100% = 1,058,823ML).

To gain an understanding of that volume of water, the capacity of the Wivenhoe Dam is 1,165,000ML.

Containment of large scale rainfall events in the Wivenhoe/Somerset system.

* All of the “large scale rainfall events” are floods.

*The proposal is that water storage in the expanded Borumba connected to Wivenhoe dam be managed, as much as is possible, to eliminate the loss of flood water over the Wivenhoe spillway so that it is available for return to the Brisbane River/Wivenhoe/SEQ Grid as required.  This would also assist in flood mitigation downstream of Wivenhoe.

Borumba Dam storage and supply capabilities including two-way  pipeline to Wivenhoe/Somerset

* The increased yield from the Borumba expanded would be 52,000ML based on GHD engineer’s calculations of 31,000ML additional from a much smaller dam which would not have the water from very large events in it’s own catchment (Yabba Creek). 

APPENDIX

This appendix will demonstrate that the expanded Borumba Dam is a far superior option to Desalination plants and recycled water.

The Water resource (Moreton) Plan was enacted in March 2007.It laid out the flow requirements of all segments of the Brisbane River that would have occurred in pre-development times.

The principal objective was that 66 percent of all water that flows through the system must reach the Brisbane River mouth and the remaining 34 percent is for our purposes. 

Being enacted by legislation, I have requested this information. It has not been forthcoming at this time but not denied.

It should be noted that the sister legislation that is designed to monitor and enforce this legislation has not been enacted although on the internet since January 2009.

The QWC has confirmed that the following graph is an accurate representation of the movement of dam levels created by inflow and extraction of the Historical Yield No Failure (HYNF) of 373,000ML annually.

It does not represent the actual dam levels influenced by the containment of allocations of water to 280,000ML. For example, in June 2006 the Wivehoe level was 30% and the Somerset 33%. Water restrictions from late 2005 also influenced the actual dam levels. The unallocated water of 93,000ML is held in reserve for contingencies such as prolonged drought.

What it does give is a reliable insight to the following:

 
(1) The draw-down on reserves from the expanded Borumba Dam required to maintain the 40% level adopted by the QWC for introduction of recycled water.
(2) The Comparison of Desalination plant and recycled water to match the reserves from Borumba.
(3) The influence of large scale rainfall events on dam levels.
(4) The approximate inflow of one of these events

What it does not give us is:

(5) The flow information on the overflow of these large scale events. Almost all of them overflowed the dams with very few exceptions.
(6) the basis of assessing the contribution towards the 66% required of the Wivenhoe/Somerset dams.  

The above graph is now expanded and overlaid with relevant information. It identifies most of the large scale rainfall events in the 120 years since 1888 when records began to 2009. It illustrates the vital gaps in these events and the backup ability of this proposal, desalination plants and recycled water to fill those gaps.

The Gaps are designated "A", "B" and "C". The QWC use of the 40% requirement to introduce recycled water is taken as the minimum dam level for security of our water supply. "A" and "B" are our main consideration with "C" requiring little attention.

Of particular note is that periods "A: and "B" did not experience a large scale rainfall event within the normal period of 3.7 years. The gap in "A" was 10 years 1898 to 1908. The gap in "B" was 7 years with 4 "near misses" taking their place.

Period "A" received no such boost from 1888 when it was full until 1903 when it was held in check by a series of minor inflows. It was finally rectified by the 1908 large scale event.

Period "B", being the one just experienced, saw no such boost from February 2001 to January 2008. It was then rectified by four "near misses in the catchments" being fills of 14.1% in January 2008, 8.0% in November 2008, 11.3% in April 2009 and finally 16.0% in May 2009 with the Premier declaring the "drought" over.  

(1) The draw-down on reserves from the expanded Borumba Dam required to maintain the 40% level adopted by the QWC for introduction of recycled water.
(2) The Comparison of Desalination plant and recycled water to match the reserves from Borumba.

Both of these items are clearly illustrated in the following schedule". They relate to the release of the 93,000ML, currently held in reserve, for consumption.

Pumping requirements: To service both "A" and "B", an initial withdrawal of 2,000,000ML is required then 760,000ML and 560,000ML to be replenished. This is permitted under the Water Resource (Moreton) plan enacted in March 2007. These are the only requirements over a period spanning 120 years.

Additional benefits of the Borumba expanded : In addition to releasing 93,000ML now held in reserve mainly for drought contingencies, there is an additional 52,000ML provided from the Borumba's own catchment. 

Costing generalisations : The estimated cost of the Borumba dam wall and two-way pipeline is $2 billion. The download and replenishing amounts to less than 10 years in the 120 years observed.

The cost of desal plants based on Tugun is $1.2 billion each plus pipes. As there are 5.5 required, this totals $6.6 billion plus pipes. The electricity requirement is 5.5 times the electricity requirement of Mt Isa each year.

Recycled water cost is unknown. It cannot retrieve the situation by itself.

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The remaining information mainly relates to the additional 80,000ML annually identified by engineers GHD when considering raising the Wivenhoe Dam wall.

(3) The influence of large scale rainfall events on dam levels.
(4) The approximate inflow of one of these events

What it does not give us is:

(5) The flow information on the overflow of these large scale events. Almost all of them overflowed the dams with very few exceptions.
(6) the basis of assessing the contribution towards the 66% required of the Wivenhoe/Somerset dams. 

(3) Influence of large scale rainfall events on dam levels : 
One can see that almost all "large scale rainfall events" overflowed the dams. They are marked in red. What we do not know at this stage is by how much.

(4) The approximate inflow of one of these events:
The event of 1908 was the only one contained within the Wivenhoe/Somerset system. It was of medium size at approximately 1,200,000ML. The only other fully internal event was 1996, being comparatively minor, when the Wivenhoe was retrieved from 47% to 90% with the Somerset full. 

(5) & (6) This area determines the availability of the remaining 80,000ML identified by engineers GHD. 

We are not in possession of the overflow from these large scale rainfall events. Calculations have been made under the "Brisbane River 66%" tab. Understandably, with the yield of 373,000ML representing our share of 34%, the 66% must result in an annual figure equating 724,000ML provided by large scale rainfall events and is flood water. The combined Wivenhoe/Somerset at 1,545,000ML capacity is clearly unable to control them as they do not happen every year and thus the figure is cumulative.

I recently received advice that the Wivenhoe/Somerset system provides 40% of the water in the Brisbane River. Under revised calculations, the 66% requirement at the Brisbane River mouth would require an adjustment to 63% for the additional 80,000ML. If the advice is not accurate, it may be required to be adjusted to around 60%.

What is certain is that almost all of the water available to the Brisbane River is flood water and as the rainfall systems generally cover all of SEQ, they combine with other flood waters that are particularly damaging to Moreton Bay as outlined in our proposal.

The release of 3% to 6% would have to be reassessed on the basis of control of these flood waters via the doubling of capacity of the Wivenhoe/Somerset by expansion of the Borumba dam to 2,000,000ML. 

An Environmental Impact Study (EIS) is required as Moreton Bay is involved. We would welcome this as it will enable all to understand the Brisbane River requirements under these changed conditions.

End     Return to Index                              

All comments welcome. Contact  hodgkin@powerup.com.au

Official statistics record over 32,000 separate computers have accessed this web-site with over 70% retaining it in their "favourites". The hit counter reset itself on one revision and the correction is beyond me. A great number of readers directly access the site via the tabs that interest them. The counter is retained for those interested.