Sketchy Rainfall Plagues Australia

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“Catchments around dams require a certain amount of dampening
before surplus run-off begins to enter storages….Spring rains this
year will need to contend with drier catchments.”
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The Age (Melbourne, Australia)
August 2, 2008 – 12:00AM

Some rain tumbled down in July,
but it’s not dam good enough
Peter Ker

THE grass may look green, but don’t be fooled into thinking July was
a wet month.

Melbourne’s rainfall figures for July fell short of the monthly
average, so that 2008 continues to be a worrying year for those
managing Melbourne’s water supplies.

The 44.4 millimetres that fell in Melbourne in July was not
disastrously below the long-term average of 47.7, but only one of the
first seven months of the year has achieved average rainfall.

That month was March, when the average was exceeded by 40%. But not
even the excesses of March can salvage the 2008 totals so far, with
the first seven months already 109 millimetres below average.

Melbourne’s storages have crept higher to 30.6% of capacity, after
rainfall over the catchments, which was 14% higher than the July
average.

The Bureau of Meteorology is predicting average rainfall for
Melbourne over the next few months, which are traditionally the peak
time for rain and reservoir inflow.

But Melbourne Water spokesman John Woodland stressed that timing of
rain was an important factor when trying to boost reservoirs.

Catchments around dams require a certain amount of dampening before
surplus run-off begins to enter storages. Spring rains last year
converted strongly into reservoir increases because the massive
downpour in July had wet the catchments.

Spring rains this year will need to contend with drier catchments.

Highlighting the problem, inflows to Melbourne reservoirs were about
half the norm in July, despite the catchments receiving higher than
average falls.

“The rain we’ve had so far this season is helping storage levels move
in the right direction, but below average run-off tells us that the
catchments are still recovering from a dry autumn,” said Mr Woodland.

“Our wettest months are normally August to October, so sustained
rainfall in that time will help us.”

Despite better than average rainfall north of Melbourne in July,
Goulburn Murray Water said yesterday the coming summer could be the
most difficult yet for farmers.

The authority had “limited operating experience” at such low water
levels, and may need to resort to carting water.

With extra water from the north-south pipeline still two years away
and the desalination plant more than three years away, officials
believe the next three months will be crucial for Melbourne’s
storages.

Opposition water spokeswoman Louise Asher said praying for rain would
be the only option available for Water Minister Tim Holding for the
next two years.

This story was found at:
<http://www.theage.com.au/national/some-rain-tumbled-down-in-july-but-its-not-dam-good-enough-20080801-3om4.html>

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