Friday, September 01, 2006

We Need a Drink!

It's the first day of spring in Melbourne, and the first day of stage 1 water restrictions.
A roundabout way of saying we haven't had any rain this winter!

It's been cold, though! The culprit appears to be a large high pressure squatting over the Australian Bight. This pulls cold air up from the Southern Ocean and over SE Australia. Simultaneously, the rain bearing fronts are pushed to the south as they come in from the Indian Ocean. This is a normal occurrence, but what appears to be happening this year is that the system is further south then usual. That, to me suggests that global warming is causing equatorial systems to expand which, in turn, pushes temperate weather systems to the north and south. (Brief synopsis, I'm sure the reality is a lot more complex!)

What have we got to look forward to? Look at the graph above. Catchments usually start filling mid June. Yet, here we are at the start of September, and the line's still drifting down. The last time the chart flat-lined this badly was in 1997.

More worryingly, the catchment levels have never really recovered from the 97-98 drought, averaging around 50%. With the prospect of another El Nino summer, it is likely that average will drop to 30-40%.

At this rate, I forecast that Melbourne's water supply will be in a critical state in ten years.