Melbourne catchments

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Melbourne catchments

Post  Johnno on Mon Sep 28, 2009 11:56 am

Thought I would do a comparison of the rain recorded in the Melbourne catchments this August & September and August and September of 2008 and there is a remarkable differance August and September and October are known for our "filling season".
The differance is this year we had a very very dry start to the year hence catching up on rainfall and wetting the ground for runoff where last year the rain at the start of the year was abit better but the past 2 months have made up for that here are the comparisons...


Rainfall 2008 & 2009 August & September in MM's then total 2 months combined in the end. 1st number is August 2nd number is September.

O'shanassy Dam: (08) 67 & 43. (09) 195 & 308. 2008 = 110. 2009 = 503

Maroondah Dam: (08) 101 & 35. (09) 84 & 151. 2008 = 136. 2009 = 235

Greenvale Dam: (08) 45 & 14. (09) 97 & 124. 2008 = 59. 2009 = 221

Silvan Dam: (08) 108 & 30. (09) 88 & 166. 2008 = 138. 2009 = 254

Upper Yarra Dam: (08) 117 & 66. (09) 140 & 159. 2008 = 183. 2009 = 299



As you can see most of the dams have been much wetter through the August & September period this year compare to last year through the same time infact put 07 and 06 in the catergory as well so good to see but we were held back from an extreme dry start to the year otherwise the runoff would of been much larger by now. Lets hope the wet weather continues for a while yet.

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Re: Melbourne catchments

Post  floydlove on Mon Sep 28, 2009 12:35 pm

Nice work John, it's great news but a shame about the very dry start. So the totals from your table are 2008= 626mm and 2009= 1512mm, nearly a 1000mm more! Hope the wet weather continues indeed. Smile

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Re: Melbourne catchments

Post  windyrob on Tue Sep 29, 2009 3:43 pm

Hey Johnno, did you work from the hourly update page or the weekly water reports archive. The gauges on some of the dams are faulty on the hourly page. O'shanassy is reading high and thomson is reading low.
The difference is still quite stark though!
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Re: Melbourne catchments

Post  Bobman on Tue Sep 29, 2009 3:57 pm

Can they cross-transfer across all dams or only some?

If one dam is 100% and keeps getting run-off through continued rainfall, I'd hope some of it would be transferred to other dams to balance it out so it doesn't go to waste.

They should have still built another dam though. Any figures on Thomson from 2008 to 2009?

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Re: Melbourne catchments

Post  hillybilly on Tue Sep 29, 2009 6:06 pm

Can they cross-transfer across all dams or only some?

Almost. They can't move it back and forth between all the dams but they can draw down the full dams into the closer in holding basins. Cardinia, Silvan and Sugarloaf are the large holding basins which have next to no runoff.

This year and last year have been chalk and cheese - we have been really luck to get great westerlies despite the presence of the El Nino which has affected most of NSW/QLD with almost all areas in these states having below average rainfall for the last 4 months.

Interesting thing this year is that the Indian Ocean dipole which usually accompanies El Nino events has not developed (this was quite prominent last year). This means that the supply of moisture for southern Vic (the Indian Ocean) is still quite active despite an El Nino. Our current understanding is that the El Nino event usually triggers an Indian Ocean Dipole which then starves southern OZ of moisture. For reasons which are not entirely clear this year (as occasionally happens) has not seen the Indian Ocean follow the lead of El Nino.

BTW October last year was an absolute shocker so this years numbers should look even better in 4 weeks time.

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Re: Melbourne catchments

Post  Karl Lijnders on Tue Sep 29, 2009 6:24 pm

Sugarloaf Dam is one of my favourite places to shoot storms from. I love that region very much. I must say the dam was up to 60% last year and the year before through the early part of Summer but then they drained it to about half of that figure over the course of 2 weeks before Christmas.

I will say that this year it could be the fullest it has been in sometime with O'Shannesy holding more than 100% and the spillway in use. Also Upper Yarra at 70% is the highest it has been for sometime officially but I have seen it at this level many times even though reported figures are not confiriming of this. Pretty part of the world up there.

The Thomson has done well the past few weeks and needs another 2 decent systems to get it towards 1/5 full.
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Re: Melbourne catchments

Post  hillybilly on Wed Sep 30, 2009 6:14 am

BTW one thing to remember is that water is pumped from the Yarra at Yerring gorge for Sugarloaf (near Yarra Glen). That means the water that spills from O'Shannesy is not "lost". There are four large pumps able to extract a total of 1 billion litres a days (enough to fill Sugarloaf in 90 days) - the numbers I read about the recent flood in Warburton was that peak flow was 6 billion litres a day (though I'd guess that dropped pretty quickly).

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Re: Melbourne catchments

Post  Jase72 on Thu Oct 01, 2009 3:38 pm

the catchments are up to 33% now, this has gone up very nice over the last few weeks or so

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Re: Melbourne catchments

Post  Johnno on Mon Oct 05, 2009 12:11 pm

Catchments up from 29% two weeks ago to 34.2% today biggest jump in a 2 week period I have seen in a long long time. I would expect them to nudge 36% by Monday or Tuesday next week with some more rain to come next few days even if its 10-20mm that will be the equivalent of 100mm if the soil was dry cos its just so wet there now

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Re: Melbourne catchments

Post  droughtbreaker on Mon Oct 05, 2009 5:37 pm

Excellent stuff, very timely coming into summer. If we can keep the wet coming (models hinting at another major system early next week) the catchments will start to see even more rapid rises. With all the minor flooding over the Yarra Valley last week you would expect to see the dam levels continue to slowly tick over even without rainfall.

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Re: Melbourne catchments

Post  hillybilly on Tue Oct 06, 2009 6:41 am

Just shows how productive our catchments can be when we get "seasonal" conditions. Suspect this event has pretty much set us up til the desal etc come on line.

Only hope that a few wet weeks don't see people kidding themselves that the drought is over (been asked this a few times already Rolling Eyes ).

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Re: Melbourne catchments

Post  Johnno on Tue Oct 06, 2009 1:20 pm

I think this drought will be be over once we get a few wet years! Perhaps a couple of years until then we are just kidding ourselves

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Re: Melbourne catchments

Post  Bobman on Mon Oct 12, 2009 8:01 pm



MELBOURNE Water and environnmentalists have rejected claims last month’s Yarra River floodwater was squandered.

Evelyn state Liberal MP Christine Fyffe said heavy flows recorded along the Yarra River last month should have been pumped into Sugarloaf dam to prop up water supplies. ‘‘The question is, why wasn’t it captured and stored in a dam? Sugarloaf Reservoir was designed specifically as a storage for overflows along the Yarra River,’’ Mrs Fyffe said. McEwen federal MP Fran Bailey said the September 29 floodwater ‘‘went straight out into Port Phillip Bay’’ and called for pumps at Sugarloaf to have extra capacity to extract more water. Sugarloaf’s primary supply is from the four pumps at Yering Gorge, which can transfer about 1G/l (billion litres) a day into the reservoir.

Levels at Sugarloaf jumped from 31.9 per cent on September 17 to 49.8 per cent last Thursday. But Yarra Riverkeeper Ian Penrose said the river’s eco-system needed periods of high and low flows.‘‘The Yarra River is on life support and its health is deteriorating. Any measures to take more water from the river are going to drive it closer to disaster,’’ he said.



Melbourne Water told the Leader it was following environmental guidelines, introduced in 2007 that state when the river flow hits 2 billion litres a day at Yarra Glen, which occurred on September 10, only the excess above 2 billion can be extracted for a period of seven days.

‘‘The trigger protects what is a naturally occurring flush of the river,’’ water supply manager John Woodland said. ‘‘Because of ongoing drought, the Yarra hasn’t reached this level at this time of year since 2004.’’

Mr Woodland said the Yering Gorge pumps were not at full capacity for four hours on September 29 due to a breakdown.

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Re: Melbourne catchments

Post  Bobman on Tue Oct 13, 2009 7:47 pm

http://www.heraldsun.com.au/news/down-the-gurgler/story-e6frf7jo-1225786418597

The current state government is one joke after another.

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Re: Melbourne catchments

Post  windyrob on Wed Oct 14, 2009 2:54 pm

That story is blown a little out of proportion Rolling Eyes The total streamflow for O'shannassy during that week was only 5000ML, much of which would have been transfered to silvan for distribution. I'm not sure what proportion was was lost over the spillway, but it cant have contributed much to the 30,000ML that flowed down the yarra. As to the size of the pumps being big enough, how many times would those extra pumps be used in any year, a few times a year when you have flood levels and thats it. not very cost effective!
If anything they need upgrade the transfer system so that water isn't lost over the spillway and can be transfered to off stream storage.
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Re: Melbourne catchments

Post  hillybilly on Thu Oct 15, 2009 5:16 am


I was down at the Yarra in Kew in May. It was just horrible. A stagnant pond of water that smelt of decay. Was easy to imagine that the entire flow was from sceptic tanks, farm runoff and local streets.

While it does seem seem like a shame to loose all that water I wonder if a flush of the river after so many years of drought is such a bad thing? I don't really have answers..

Personally, increasing the size of O'Shannassy and Lake Glenmaggie (and having a flood off take on the latter for Melbourne) seem like sensible options, but perhaps the water generated just doesn't make sense when you look at the costs Question

It strikes me as a huge shame that politics is played over things like water, climate etc in OZ. There are things which go way beyond electoral cycles and which should be beyond politics IMHO.

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Re: Melbourne catchments

Post  Anthony Violi on Thu Oct 15, 2009 11:37 am

Always the way with politics DJ...votes get priority..If we had have dammed the Mitchell our storages would have been close to full despite one of our worst droughts on record. Seems logical to build new dams and increase the other catchments instead of building a desalination plant.

Anyway should see totals rocket up soon with all the runoff and snow...the govt is already slowing the figures down...
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Re: Melbourne catchments

Post  hillybilly on Thu Oct 15, 2009 5:05 pm

If we had have dammed the Mitchell our storages would have been close to full despite one of our worst droughts on record.

Personally I would prefer a serious look at piping water from northern Tasmania. The quantities available are huge, and that region has a very reliable rainfall climate.
It will also be less affected by global warming/climate change.

It could have been a real money spinner for Tasmania.

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Re: Melbourne catchments

Post  Malleefarmer on Thu Oct 15, 2009 6:48 pm

Here a thought stop melbourne gowing and you will not run out of water!!! Instead they want to steal water from all over instead of spreading population out to where the water is. There was even a suggestion of piping grampians water to Melbourne..... we are not even at 20%!!!

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Re: Melbourne catchments

Post  Karl Lijnders on Sat Oct 17, 2009 8:44 am

Well that would be nice Anthony but I think that is not the solution at this time.

I have noticed that some of the rainfall sites have been taken offline from the BoM flood warning page, suprise suprise. This always happens when there is significant rises in the rainfall and inflows.

Warburton recorded 5mm on Thursday according to the BoM site which is garbage because I was personally there on Thursday and I would think about 15-20mm had fallen til 3pm that I was there and then had the subsequent thunderstorms and rain that moved in from the Naree Warren region.

Anyhow look for a 1.5%-2% rise over the coming week or so.
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Re: Melbourne catchments

Post  droughtbreaker on Sat Oct 17, 2009 9:13 am

The Melbourne Water Mt. Macedon gauge went offline too for a significant period earlier this month and I have had suspicions it has been slightly under recording as well. I put this down more though to the fact that these automatic rain gauges might not be the most accurate or in the best position for recording rainfall as compared to the BOM AWS gauges and they are not verified or checked at all, purely there to transmit flood alerts to MW and the BOM back in Melbourne when there is sustained heavy rainfall. I'd love to know where the MW station is up Mount Macedon. I would guess it is somewhere near the Orde Hill res above the Mt. Mac. village area and if that's the case it could be affected by strong winds and tall dense forest blocking the gauge from rain. Is the Warburton site a MW one? If so then the same factors could be a problem sometimes.

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Re: Melbourne catchments

Post  Anthony Violi on Sat Oct 17, 2009 1:26 pm

I can tell you for a fact Andrew its a man made fault...we wouldnt want the paying consumer to know how much water we really have do we???

And i think DJ any of those two scenarios, the damming of the Mitchell or water from NW Tasmania would have been beneficial for our storages and helping the economy of both states..both areas recieve good rainfall regularly so it makes good sense...but no lets build a desal plant Rolling Eyes
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Re: Melbourne catchments

Post  Karl Lijnders on Sat Oct 17, 2009 1:44 pm

Oh and the desal' plant location has been under flood watch all week which is just mind boggling!!!
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Re: Melbourne catchments

Post  Ice Storm on Wed Oct 21, 2009 11:26 am

Hi Guys,

I was staying in Healesville over the weekend, and took a trip up to the Maroondah Dam. Fabulous to see it full and over flowing. I am unsure when this last happened. Some people have suggested 10 years, others 4, so I can't be too sure! Does anyone know??

Here are some pics tinged with a little sadness when you see charred logs...

(if the images are too big, please let me know and I can change to smaller!)










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Re: Melbourne catchments

Post  Karl Lijnders on Wed Oct 21, 2009 1:59 pm

Thanks Jane :-)

If only it could rage like this until years end.

Pretty part of the world. Runoff at 3100ML and nearly 37% capacity now so good going!!
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Re: Melbourne catchments

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