The Australian Weather Forum

Do you have a link by chance?

Sorry but i can't find the link but here is what the article said:

"Most of Melbourne's dams are brimming if not overflowing, except for the Thomson, our biggest water storage. So why is the Thomson hovering around 38% capacity? Why did it miss out on the record summer rain and the good autumn rains? Senior engineers in Melbourne water say the Thomson Dam was never finished. In fact, they claim "its catchment is too small given it's storage volume to make the most of any good rainfall".

The Thomson was commissioned by the Hamer Government and opened soon after the crippling drought of 1983. You may recall the dustsotrm that engulfed Melbourne on February 8, when day turned to night. A week later Victoria was ablaze with the Ash Wednesday fires that claimed more then 70 lives. Some say the Thomson dam was never finished because of politics. The drought had broken and water supply was no longer a top priority. The oroginal Thomson dam project included part of the Aberfeldy River catchment as well. That was to be achieved by damming the upper reaches of the Aberfeldy and dirverting the stored water through a tunnel into the Thomson.

Apart from the Thomson catchment being far too small, there is another problem. The dam lies in the lee of Mount Baw Baw and the prevailing west to northwesterly winds dump most of their rain on the other side of Mt Baw Baw, The Thomson gest very little compared with the Upper Yarra dam on the windward side of Mt Baw Baw. The Thomson dam can fill only if it is exposed to regular and moist southeasterly winds. Winds like that are relatively rare over the catchment. A stationary low-pressure system over eastern Bass Strait is the only weather system capable of dumping torrential rain in the catchment and making a significant impact on the Thomson. The La Nina that's ending may hold the key. We couldf see such downpour early this winer.

Historically, when a strong La Nina breaks down, there is a good chance of the Thomson getting what it needs."

Interesting reading, thanks for that Rhys. We know the far east of the state largely missed out on the rain over summer. And I do recall the Thompson does well went we get a good ECL scenario, pity we haven't had one of those for a while. Which year did we have succesive ECL's , it was 2-3 years ago, i think??????? I remember area's of Gippsland were flooded right in thr height of the drought.

Things are looking up....Thomson is about to hit %50...

http://www.melbournewater.com.au/conten ... asp?bhcp=1

66.3%

It's been a long time since anyone's been here!
I was just checking Melbourne Dam levels (which are a healthy 70.3% and rising), which lead me to this rather shocking image...
What's going on Melbourne Water? Has Maroondah Reservoir sprung a serious leak in the last month? From 78% to 38% in one month???

Hello,

What I think is going on is the following:

1. Melbourne water are conducting environmental releases from Maroonda, Oshannassy and Upper Yarra. This is to boost flows in the Yarra for the greyling fish which now can travel up stream.
2. At the same time Sugerloaf is a bit down, so some of that water is being pumped into that off stream storage
3. This all lowers the catchment storages listed above. In the past Maroonda and Oshannassy have spilled over for months on end. So if we go really wet they have capacity to store it all - muddy rain water too, while the off stream storages supply Melbourne.

There looks to even have been some transfers from Thomson to Upper Yarra and some releases from Thompson, but looks to have stopped now.

In a nutshell environmental releases plus moving water from catchment storages to off stream storages.