Sunday, December 04, 2005

Finally some rain where it counts.

It must be Christmas. Finally, finally some rain has fallen in the Warragamba Dam catchment area, despite the fact that NSW has just had the wettest spring since 2000 with average to above average falls. Sydneysiders, long used to water restrictions brought on by the drought and the many false promises of rain falling outside the catchment will not know what to do with themselves.

Yet there is not enough reason to get light headed and wash your car though; this increase in dam levels will only supply us with water for two weeks. If Sydney's catchment area gets no more rain, the dam will run dry in two years.

The reason why so much rainfall misses the catchment area of the Nattai River, the river that gives Sydney 80% of it's water, has been hypothesised by a Macquarie University physical geography professor to be a result of extensive clearing of natural vegetation as great swathes of suburbia are laid down. Using computer modeling Professor Andy Pitman determined that:
the vegetation loss had changed the dynamics of atmospheric convection, which is a key to forming many thunderstorms that strike Sydney on summer days. Without the vegetation, sea breezes could sweep further inland, changing the location where they collided with winds blowing from the south-west.
In related good news: The Australian Bureau of Meteorology climate officer Mike De Salis says the El Nino ocean pattern is subsiding, leading to wetter conditions for eastern Australia. Forecasters predict the drought is finally coming to an end.

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