Author : J. V. Hodgkinson F. C. A. Chartered Accountant : Aug 2006 to November 2013    

The principal thrust of this website is
FLOOD PROOFING BRISBANE from damaging floods to the point of extinction. MITIGATING flooding in Ipswich and Gympie. Putting REAL MEANING into "Drought proofing SEQ" and ensuring our water supplies by natural means well into the future

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






·       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.  Click the tab 

Ron McMah   Imbil
Trevor Herse   Gold Coast
John Hodgkinson    Brisbane


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 19th 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.




Expand the Borumba Dam to 2 million ML
Connect a two-way pipeline from Wivenhoe/Somerset to the expanded Borumba
Build a hydro plant into the Borumba Dam
Consider connection of the Borumba with the Northern Interconnector pipeline to service storage for the North Pine and Baroon Pocket dams and any other Dams in the grid system


210,000ML annually available (Compared to Traveston all three stages 150,000ML)
Wivenhoe/Somerset dams are too small to maximize “large scale rainfall events” described by SEQWater as "Uncommon events". They are our main water supply.
Storage capacity in the combined Wivehoe/Somerset and connection to the expanded Borumba, doubled to 3,000,000ML. This is sufficient to cater for ecology and our growing population during a 14 year “drought” being the longest historical absence of our major inflow “large scale rainfall events”.
Desalination plants not necessary
Partial flood mitigation of Gympie
Dam already at Borumba
We own all the land
Major tourist attraction for the largest dam in South East Queensland


Dam wall and hydro $1.4 billion (Reference JWP Engineering for a 3 stage wall to 1,650,000ML plus Hydro.) Wall to be built in one stage to 2,000,000ML
Pipeline $0.5 billion. We were assisted by a senior engineer engaged in the construction of the Wivenhoe Dam. He provided pipeline calculations and also a cost assessment. He described it as a “heroic” cost assessment.
Capital cost of 4 desalination plants based on Tugun is $4.8 billion plus distribution pipes ($1.2 billion X 4 = $4.8 billion).
Pumping costs will be assisted by the hydro plant. The distance is 60klm with an elevation of 40 metres from point to point.
Electricity cost estimates for the same volume of water is 66 per cent of the cost of desalination and may be much lower depending on the Hydro plant contribution.


Construction of dam wall, hydro plant and two-way pipeline, approximately 4 years
Wivenhoe/Somerset should overflow in that period. If not, on past experience, the expanded system will begin operations soon after due to a shortened period of the maximum historical departure of “large scale rainfall events”.

If the Wivenhoe/Somerset does overflow in that period, then near full dams plus reconstituted water and other initiatives such as the raised Hinze Dam should outlast any lengthy period without “large scale rainfall events” with our present population. Reconstituted water is desalination at Tugun and recycled water


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



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 theSummer Rain Courier Mail 10 02 7.jpg (371046 bytes) 10th 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. TheyDecile_Graph_1899_to_2006_W.jpg (226292 bytes) have the ability to disguise themselves in official statistics. One half of the 20th 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 majorYears to fill.jpg (97872 bytes) water supply but are random in their nature with little reliability in timing.

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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 yearsFrequency large scale.jpg (154720 bytes) 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

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.

2.3 They are observable in the short life of the Wivenhoe commissioned in 1986. The dam was filled toWivenhoe Uncommon to 2009.jpg (86136 bytes) 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.

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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 thePercent_Som_with_40145.jpg (278710 bytes) Percent_Wivenhoe.jpg (254083 bytes)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

3.2 The overall rainfall deficiency of 20% was almost entirely in the non-summer months stretching over the 8 months April to November. This period normally receives only 46% of the rainfall and produces little inflow. The 20% deficiency applied fully to the non-summer period has little influence on the “worst drought” theory.

Official population statistics displayed no suddenPop_graph_4.jpg (86814 bytes) uplift. They were predictable and were in keeping with their predictions.

Photo : Official population statistics showing no sudden uplift

3.4 What was missing was a “large scale rainfall event”. We were experiencing one of the large gaps that,Wivenhoe Uncommon to 2009.jpg (86136 bytes) from past experience, can stretch to 14 years. You will see from the dam level graph the impact that had on dam levels.

Photo : Wivenhoe dam level graph overlaid by large scale rainfall events. An important document that is not published elsewhere.

his gap in large scale rainfall events lasted 6 years. We were rescued by four “near misses” that failed to fully cover the catchments and thus failed to develop their full potential. Cyclone Hamish missed us altogether. They provided 49% of the increase of 57% in dam levels.

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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 In the short space of time available after recognition that something was wrong, some very good initiatives were undertaken including raising the wall of the Hinze dam, water tanks and the re-education of SEQ residents and business to reduced water methods.

Recycled water was also a good initiative. However, with low levels of use of the primary water, the low volume produced would take 21 years to fill the Wivenhoe/Somerset dams from this source if no water was taken.

The main “drought proofing” methods that received examination were the Government preferred Traveston Dam proposal and desalinated water.

4.2 Traveston dam
proposal was on the Mary River . Both the Stanley River and the Mary River have adjacent catchments. Their sources are in the Mt Mee area. They begin to flow to the coast by rights but due to some geological anomaly turn west and find their inland route to the ocean.

They have exactly the same rainfall in periods without large scale rainfall events and rainfall is received inMary valley compare Somerset BOM figures.jpg (238533 bytes) exactly the same pattern. The result under these conditions would not have supplied the additional water required as summer rainfall is approximately 1/3 of our water supply. Doubling of that would have left us well short with increased population requirements.

Photo : Rainfall graph of the Mary and Stanley Rivers showing the commonality of both Rivers

The Traveston proposal is now consigned to history.

4.3 Desalinated water has been again put forward as the only available option to make up the leeway caused by cancellation of the Traveston. On the face of it, it may seem reasonable.

It would take the Tugun desalination plant 34 years to fill the Wivenhoe/Somerset if no water is taken out. (1,560,000ML / 45,000ML = 34 years)

The annualised water from “large scale rainfall events” based on the measured experience of the Wivenhoe is 417,567ML. To maintain that supply, we would need not less than 9 desalination plants of the capacity of the Tugun Plant. (417,567ML divided by 45,000ML = 9.27)

A preliminary cost comparison of moving the same volumePumping at Household.jpg (144621 bytes) Pumping at Wholesale.jpg (148665 bytes) of water up and down the pipeline to Borumba is that desalination is 50 to 100 per cent more expensive than the Wivenhoe/Borumba operation. A preliminary cost comparison of moving the same volumePumping at Household.jpg (144621 bytes) Pumping at Wholesale.jpg (148665 bytes) of water up and down the pipeline to Borumba is that desalination is 50 to 100 per cent more expensive than the Wivenhoe/Borumba operation.


Photos : Pumping calculations for comparison of Desalination and Pipeline to Borumba at "Household" and "Wholesale rates".


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Solution - Alternative solution is based on knowledge that the 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 statement. Recent history shows that the periods without “large scale rainfall events” can last up toFrequency large scale.jpg (154720 bytes) 14 years. This last “water crisis” which caused us so much pain, particularly to the people of the Mary Valley, fortunately lasted only 6 years. So how do we provide counter measures?

Photo : Large scale rainfall events since 1841 to 2006 together with their probability

The answer requires wider thinking.

There is more than enough water available in the Wivenhoe/Somerset system to cover the ecology of the Brisbane River , our present requirements and protection of Moreton Bay from damaging flood water

Raising the Borumba dam wall to a capacity of 2 million ML will increase the total storage capacity available in the joint Wivenhoe/Somerset/Borumba to more than double the current storage capacity being the Wivenhoe/Somerset system. (Wivenhoe 1,165.000 + Somerset 385,000ML = 1,550,000ML)

5.3 Managing the dam levels at around 50% gives us capacity in the Wivenhoe/Somerset system to retain 750,000ML for pumping to the expanded Borumba. Temporary use of a further two metres of the operating level gives us a further 300,000ML. Thus around 1 million ML can be pumped to the expanded Borumba at our leisure.

5.4 As “large scale rainfall events” generally cover all of South East Queensland, the Borumba catchment canGympie Times P2.jpg (361826 bytes) provide a fill of up to 500,000ML and sometimes more. Thus we have spare water of around 1.5 to 2.0 million ML available for the ecology and ourselves. That is about 11 years work for 4 desalination plants the size of Tugun. Smaller plants were initially proposed.

Photo : Gympie times observations of the 1999 flood in the Borumba.

5.5 The “Water Resource (Moreton) Plan of 2007 requires a review to provide for the incorporation of this storage capacity. The Act provides for change and is designed to be flexible.

Currently Ministers Hinchcliffe and Robertson are bound by the requirement that 66% of all water that passes through the Wivenhoe/Somerset system must reach the Brisbane River mouth. People of South East Queensland would be surprised to learn that of the 73% now in our dams, we are only entitled to 1/3 and the rest is for the River. The Law to monitor and enforce it has been on the internet since January 2009 and is expected to be finalized by December 2009

In addition it is now known with certainty that floodMoreton Bay flood.jpg (158208 bytes) water degrades the water quality of Moreton Bay. This water is almost all flood water as witnessed in the short life of the Wivenhoe Dam, filling the dam from scratch and overflowing a further 4 times.

Photo : Recognized official report recording a "D" for Moreton Bay caused by flood water

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)

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).

There is a further 80,000ML identified by engineers GHD when they considered raising the Wivenhoe dam wall.GHD P 667.jpg (102189 bytes) 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:

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.

So a volume of water almost as large as the Wivenhoe Dam must occur each year to comply with the WRP. An impossible situation but currently that is the way the Act is written.

To accommodate the 80,000ML identified by engineers GHD, how much does the Wivenhoe/Somerset contribution to the Brisbane River have to be reduced?

Under the 66% rule the required volume is 698,823ML.(1,058,823ML -360,000ML). A reduction of 80,000ML represents 11.5%.

However, the Wivenhoe/Somerset contribution to the Brisbane River is 40% overall. The reduction at the Brisbane river mouth is 40% of the required 11.5% = 4.6%.

The Brisbane River mouth requirement of 66% is to be reduced by 4.6% to 61.4% in order to retrieve this 80,000ML.

Offsetting that reduction is control over flooding in Moreton Bay and controlled releases to suit the environment.

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6.0 The facts that we have at our disposal are now listed:

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

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

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

* Floods degrade the quality of the water in Moreton Bay as defined by a report published in October 2009 in the Courier Mail.

* The Wivenhoe/Somerset system is too small to contain them with four going over the top in the short life of the Wivenhoe. In addition they filled that dam from scratch giving a false sense of water security in Brisbane .

*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.
*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 Borumba dam is currently a small dam of 45,000ML.

* We own all the land via the Qld Government.

* It has a hard rock catchment that is small at 466 square klms.

* Government appointed engineers GHD indicated that it could be made into a 2 million ML dam, or higher, making it the largest dam in Queensland.

* It is a natural amphitheatre.

* It is 60klm from the Wivenhoe dam and 40klm from the Somerset.

* It will require an EIS (Environmental Impact Study) but has the backing of most in the Mary Valley who have had a link to my web-site for sometime. We have been in close touch. Of course a dam is already in existence there.

* A much smaller expansion of the Borumba dam was proposed for the second phase of the Traveston proposal so no opposition to the principle of expansion would be expected from the Government.

* 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). 

* The cost of a dam wall built in three stages and at a capacity of 1,650,000ML was provided by GovernmentJWP Dam only.jpg (51660 bytes) appointed JWP Engineering at $1.4 billion. It includes a hydro plant to mitigate pumping costs. It is reasonable to assume that the wall built in a single stage and to a height providing 2 million ML capacity would be in that region of $1.4 billion.

Photo : Engineers JWP Engineering calculation of a Borumba Dam wall in three stages to 1,650,000ML together with Hydro.

* The pipeline details with all its engineering workings was provided free of charge by the supervising engineer who built the Wivenhoe Dam. His name appears on the dam plaque. It appears in the web-site under the solution tab and in my EIS. His “heroic” assessment of cost was $0.5 billion which appeared to be in order after he directed me where to check the pipe costs.

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