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 April 2008

  UPDATES : November 2008. This website is maintained as it was in April 2008. Currently the Dam levels are around 40% and, with the addition of the Grid, should be maintained around that percentage. The next "uncommon meteorological event" will fill the Dams to overflow. This event will show that that the actions of "uncommon events", being Monsoons, Cyclones or Large Rainfall Depressions that generally cover all of SEQ, is again misunderstood and that they are the major source of our water supply. Our current storage capacity is insufficient to deal with them. The historical fundamental flaw of the cancellation of the Wolfdene Dam (1989) is being repeated in reverse at Traveston Crossing in the Mary Valley. See "Home" page for further updates.

WHAT OUR LEADERS AND DECISION MAKERS BELIEVE THE SITUATION TO BE.

Our Premier has recently resigned and has been replaced by the Deputy Premier. However their comments at the time are relevant.

Our chief decision makers were firmly of the opinion that a major drought is the cause of our depleted dams. This was followed by the Water Commission with similar views and expressed in their advertisements.

This brochure insert appeared in the Courier Mail on the 3rd February 2007. It confirmed that our two chief decision makers at that time were attributing our depleted dams to " the worst drought on record". They also introduced the influence of a rapidly expanding population and its water requirements. The map is 6 year map and important to these observations. It is now expanded for clarity. 

The map shown is clearly a decile map. A decile map grades the rainfall in decimal categories of 1 to 10 with 1 being "the lowest on record". The last 6 years may not be the lowest but they are in the lowest 10%.

I retrieved from the Bureau of Meteorology a "percentage" map of the same rainfall for the same 6 years. It shows 80%.

The stability of district 40 in which the catchments reside permits this 80% to be classified in the lowest on record category because the catchments have never received less than 80%.

It should be recognized at this point that the Qld Govt sponsored "Climate Change Centre of Excellence" reported the catchments as receiving 76.2% and defended it as a "Drought" rivalling the "Federation drought". There was no indication that they were aware that the balance of 23.8% occurred in the low to nil inflow non-summer months which have little impact on dam levels. Refer to "Rainfall deficiency" and the " Federation drought" buttons.

Decile evidence of 6 year periods for both the Wivenhoe and Somerset dams will provide more clarity on that statement. In the Wivenhoe there are 7 periods of 6 years in the last 100 years that are within 66mm ( 693 to 759 mm) mm of the last 6 years. With one exception, there were no "Uncommon event" within those periods.

The 80% of long term average rainfall does not fit within the Bureau of Meteorology definition of a drought being "acute shortage of water" in the context of rainfall. 

Press release on recycled water 28th January 2007

Relevant comments on rainfall were made by our leaders when announcing the cancellation of the vote on recycled water. They are contained in "Rainfall 2001-06" button.

Of particular interest is the comment that it may take 5 to 10 years to fill the Wivenhoe to 40 percent. It was made in the context of "below average" rainfall which has been examined in detail in this web-site.