cosmicalstorm wrote:I know little about this problem, what future is Australia in general looking at if they dont get their heads out of their asses and starts to do things about the water shortage?
I presume it varies by state: Adelaide currently gets 20-90% of its drinking water from the Murray-Darling system, depending on rainfall. This comes out of the city's water allocation which is in a sort of five-year bank. Since we've had a few more drought years than usual lately, we've had to create an extra emergency Adelaide city water allocation, because we're pretty much used up our allocation. This comes out of a 6,000GL/year allocation (I think - there could be extra zeros there) which is guaranteed South Australia by the constitution.
The Riverland is also facing problems due to the shortage of Murray water. While most irrigators along the Murray use annual plantings, the guarantee of water for South Australia means that irrigators in SA have permanent plantings - mainly oranges and grapes. Even though the irrigators in SA have used the most water-economical irrigation techniques available during the last century, the drought is hitting them hard, since it costs a lot more to lose or replace a permanent planting than you lose from a bad year for wheat etc.
The problem with the lower Murray lakes at the moment stems from a few sources: first of all, less water has been coming down the Murray in recent years (the 6,000GL is a minimum, not a maximum). Secondly, the average temperature in South Australia has risen due to global warming, which results in increased evaporation. Thirdly, the lakes are actually a naturally estuarine environment, and are only kept fresh because of the Hindmarsh weir. It's a little-advertised fact that the vast majority of South Australia's water allocation is actually caused by evaporation from Lake Alexandrina and Lake Albert. The lakes could actually be rescued quite easily by simply removing the weir and letting ocean water in. Since the water levels in Lake Albert are so low at the moment that the farmers who rely on irrigation from the lakes can't pump water from them, this solution may no longer be politically unfeasible, since the farms are going to go broke anyway. Finally, a large amount of the water from the Coorong was actually originally run-off water from the South East. Then this water was tapped for irrigation, so now the Coorong's gone to the shitter.
One issue in SA, actually, is that global warming is giving us decreased rainfall.
Goyder's line, which marks the boundary between farmable and non-farmable land is moving south. That's actually a quite significant decrease in our arable land.