A
few of the principal statistics have been graphed for visual comprehension. This
graph shows the Sq Klm of the catchments.
Dam
capacities highlight the enormous capacities of our Dams. The Somerset was our
mainstay until 1986 when the Wivenhoe was commissioned.
Again
the deterioration in our Dam levels. Of minor note is that the annual report of
SEQWater for the year 2005 was incorrect. The Dam levels at 30th June 2005 were
deducted from the 30th June 2003 levels instead of 30th June 2004. It has been
adjusted in these figures.
The
SEQWater web-site provides the overall statistics of the dams. Of particular
note is the completion dates of the Wivenhoe in 1985 and the Somerset
in 1959.
The expected annual rainfall in the Wivenhoe at 940mm and the
Somerset at 1,230mm is puzzling. You will see from the charts in the
"rainfall stats" section that they both appear too high and would
place them
permanently in a position
of "below average" rainfall. I
have requested an explanation in writing but it has understandably been ignored.
They are currently busy people and have been most helpful in their public
pronouncements. The attached graphs further highlight this minor
puzzle.
The
other aspect of note is that the Annual water supply is currently
under review. This attachment was their previous assessment. It suggests that
the annual flow into the Wivenhoe and Somerset dams is 446,900 megalitres. That
is 1,224 ML per day. Quite adequate for our unrestricted use as compared to the
restrictions now in place. If you examine the "Key features" above, you will see that it currently under review.
Reference is SEQWater Environment report 2001-2002 page 2.
For
those readers who are unfamiliar with the Location of the Dams and their
catchments, I have included a contour map available from the SEQWater
web-site. I have overlaid the town names and catchment boundaries for
readability.