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.

SEQWater has by inference indicated that Summer Rainfalls were the main areas for high inflow into the Wivenhoe and Somerset Dams, uncommon events excluded.

They nominated three Rainfall Stations, two in the Wivenhoe and one in the Somerset.

They are correct. Attached is a summary of all the recording Stations in the Dams, some dating back to the 1880's. The Summer rains have without fail registered 50% or better in the 4 Summer months December to March. The balance, of course, was received in the non-summer months.

Almost all high impact rainfall that creates inflow was received in the Summer months. There are a few notable exceptions and attention is drawn to them where required.

The information is split into two sections. Rainfall up to 1964 and rainfall after that date. There is a slight variation between the two that do not alter the point of this exercise. I have referred to it in the "Climate Change" button.

Mary Valley ( Proposed Traveston Dam ) adjacent catchment area.

The Bureau of Meteorology rainfall statistics for the Mary Valley to the proposed Traveston Crossing are enclosed. They show that the four Summer Months exceed the eight non-summer months.

This is not surprising as the Mary Valley experiences the same rainfall pattern as the Somerset/Wivenhoe system. This has important consequences when dealing with "uncommon events".

CONCLUSION

The consistency of the data as between rainfall Stations and periods has facilitated the comparisons in both Dams dating back several years to the early 1900's.

It had a major effect on determination of the cause of our depleted dams in the years 2001 to 2006.

The Summer Rains, with the exception of uncommon events, have produced almost all the inflows into the Dams. There are minor, but some important exceptions usually on the edge of the non-summer months namely April /October /November.

Summer Rainfall has been used throughout the web-site and the exceptions that occurred in the non-summer months noted where applicable.