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Discussion in 'Daily & Chat' started by Hunter, Jul 22, 2016.
Kiewa sports ground under water if that's any help.
good news is that the system has finished(well we hope that's the case) and very small rainfall amounts are expected for next four days...fingers crossed river systems slowly recede from now to Melb Cup time....
This site will show more helpful data: http://livedata.mdba.gov.au/system-view
So it's a very wet spring and the catchments are saturated. Just about all rainfall immediately becomes run off. On the MDBA site Biggara is 13 GL/day and Bringenbong 26 having an input from Snowy Hydro. You can go to the Snowy website and check Khancoban releases which they try to keep under 10 GL as this is the channel capacity of the Swampy Plain River. So 13 + 10 is 23 so another 3 GL flows in from minor streams upstream of B' bong to get 26 GL. And so it goes downstream with gauges at Jingellic subject to Murray flows and input from the Tooma R. This all adds up to give the current 89 GL inflow to Hume Res.
THis is not too dramatic in terms of flooding but of interest to us is the management of releases from Hume, the thundering spillway and any downstream floods..... W
It's pretty dramatic when you stand on top of Huon Hill and see the huge sheets of water extending from the Kiewa all the way down to Barnawartha.
And between the Jingellic gauge and the Lake itself are hundreds of little run-offs and creeks such as Sandy Creek, Granya Creek, Double Gully etc plus a myriad little gullies all of which are rushing noisily into the lake. There was quite a shower over Sandy Creek way this afternoon too.
Lucky temps were cold enough for snow. Could have been even worse if all rain.
Twas rain at lower elevations and that snow will melt quickly if the next front rains on it. This is what happens in October. The snowpack is near to 50% water and add 75 mm of rain and it's rapid liquification..... W
Whoa. That's a lot of inflow. 11 gates open but they've raised them up a bit. Will take a few days for all this to settle down I imagine.
Parts of the main street in Wangaratta being evacuated as the levee starts to leak.
That is very bad news.
Flow has been reduced a bit out of Hume.
would love a photo of that, am very familiar with that view!
99% capacity as of yesterday at Hume.
Yet more rain fell overnight in the catchments of the rivers feeding Eildon, which is now at 73.5% and filling very quickly. A couple more rain events dropping 10-20mm this month and we could see it hitting 85% by Cup weekend.
Does anyone have visibility of Dartmouth Dam - this is bigger than Hume but doesn't seem to have received the same level of inflows over the past few months. Only tracking around 70% capacity?
Wondering if the inflows be mainly from snowmelt
Holds another 800,000 odd ML more than Hume, and isn't fed by the same kinds of rivers as Hume. The Hume gets fed by the Murray (obviously), but the Murray is also supplemented by water from the Snowy Mountains Scheme, and water downstream from Dartmouth.
Due to this, Hume often drains down to 20% or less of capacity at the end of summer, and fills up over the course of the wet season.
Dartmouth is a slow filling, slow releasing dam, and was built to increase water security in years of drought, or consecutive years of drought.
This paints a good picture: after the prolonged drought of the mid to late 2000's, Dartmouth was holding around 20-25%. Even after the drought broke in and around 2010 and the La Nina that followed, Dartmouth didn't reach full capacity at the end of 2011 (it held around 3GL):
Compare the above with the corresponding years for Lake Hume:
Apart from 2011, where it was pretty much at full supply level throughout the year, the dam gets drained down to less than half of its capacity come early May, and then depending on rainfall and inflows, it peaks by mid to late Spring.
What we've seen at Hume in 2016 is similar to 2010 - an almost 2.5GL rise in capacity, but this year it has filled quicker by around a month.
Interestingly - note the curve in the 2010 line in early September at Hume. Looks a little too smooth? Then check out the 2010 line at Dartmouth. Same time, same shape albeit smaller. Corrupt data at both?
Great info - thanks Edgecrusher
I find it interesting.
I wish those graphs went in year order. 2009, 2014, WTF.
Want me to change them around?
I tried. No matter what combo I enter the years, it won't enter them chronologically
Can't handle. head exploding.
SELECT `title` , `text` , `date`
ORDER BY date DESC
LIMIT 0 , 30
One the great things about the forums is that people know good stuff and share
But why in 2015, did Victorian storages (Eildon the same as Dartmouth) get so depleted. It wasn't that dry.
Was it electricity generation? Environment flows? Or trying to create an environment to turn on desal and the pipeline?
Umm, it kinda was. Here's the twelve month period that preceded the big wet:
But given Dartmouth and Eildon hold a couple of years' worth of water, the previous TWO years paints a similar picture:
Reduced inflows over multiple years means dam levels drop
It was a very dry season in South Australia, and I remember the Hume being drawn down very early last spring, as early as October from memory. The demands were high (requests for water) and the Hume hadn't filled from the spring wet, so the water disappeared very quickly down the Murray. Plus a lot of evaporation I guess.
I expect this season will be the reverse: a lot of rejections (we have enough water thank you) so the draw down won't be as dramatic, plus later in the spring/summer.
Sure, but those dams are meant to be able to sustain rural areas through several years drought, not just 1 or 2 drier years.
I'm not quite sure what point you're making here Teckel.
I'm not making a point, per se. It's just that I don't feel an adequate explanation has been given as to why they seemed to pull the plugs on the dams in 2015. One dry year is not a drought. And what if 2015 had been followed up by 5 more dry years. There would have been nothing left after the 2nd year at the rates they let them empty.
Well, that can happen and has happened. The Hume's storage is roughly equal to a year's demand downstream. It's always been an irrigation dam first and foremost, not a water storage like Warragamba or Dartmouth. It's too shallow for that and it's designed to fill and empty every year. Therefore if we have several dry years, like what happened up to 2009, there is very little water in the dam. It's meant to release all its water. I can't say it any better than that, sorry.
That's what I'm talking about - Dartmouth and Eildon. See the graph above for Dartmouth.
Dartmouth has always supplemented the releases from Hume in years of high demand. I don't know about Eildon - I'm guessing it pumps water into the Melbourne catchments for urban needs but I have no idea of its recent history, except when it was dry up to 2009.
Lake Eildon is connected to the metropolitan water supply of Melbourne, the state capital, via a pipeline from the Goulburn River. On average, 91% of the water from Lake Eildon goes to the Goulburn Weir and the Waranga Basin before it flows to irrigators in the Goulburn Valley system.
To say it is 'connected' is utter b/s.The previous labor government built a huge pipeline to pump the farmers irrigation supply over the Great Divide to keep Melbourne's lawns green. I don't know if it's even been used. Libs turned it off. Current labor desperate to use it.
Thanks for that. Good to know.
Not a conspiracy, just how the system is managed. All of the water stakeholders follow things very closely. You'd have to fool a hell of a lot of people downstream to release water solely for political purposes.
If you look a Hume and Dartmouth together you see that in 2015 water was released from the Dart because water levels in the Hume were low.
Same thing happened in 2014 but to a less degree because the Hume was less empty.
In 2009 water in the Hume was lowest of the selected years, but there was insufficient water in the Dart to release water into the Hume.
So who thinks Dartmouth is good for more than just one year of drought? Somebody at the MDBA told me that 1 year is about all its good for AFAIR. And now the Murray floods are causing a " blackwater event " in which leaf litter on the flooded forest floor depletes the oxygen in the water thus leading to fish deaths when it rejoins the main channel.
Looks to be all over wrt floods at Hume. The very wet Sept is not being followed by a rainy October..... W
A strong cold front and associated trough will cross the Bight on Saturday, approaching western Victoria Saturday night. The trough and cold front will move across Victoria during Sunday, clearing the east by early Monday. Another cold front will approach late on Monday before crossing the State on Tuesday.
These fronts are forecast to bring rain and showers to North East Victoria on Sunday, Monday and Tuesday. Three-day rainfall totals of 20-40mm are forecast, with up to 60-70 mm possible on the ranges.
North East catchments are saturated following recent rainfall. With the forecast rainfall, stream rises are expected and areas of minor flooding may develop from Sunday afternoon onwards.
So we could see more flooding next week
Hume stopped spilling on Saturday but only has 60 GL airspace. Perhaps 600 would be better insurance considering the BoM outlook. Here in Sydney east of the divide the ground is cracking due to an inconsequential 6 mm at Bankstown in the last month and lots of dry cool westerly winds making it feel like August...W
NSW ranges already have had 65 mm at PB and 81 at Thredbo Village in under 12 hours. But Cabramurra only 29 and Khancoban 32. Back of the envelope gives 200 GL into Hume just from this lot with more to come......W
So you were saying the floods were now over given October's been dry...
We've had fronts come through the last three Sundays in Melbourne. Looks like a bit feel in the Vic ranges as well: 20-30mm.
Another 10-25mm forecast up there on Tuesday as well.
Whingers are out in Deni blaming Dam management for their flood issues. Like clockwork.
Thinking there is some desal conspiracy with how eildon is managed is loony. A totally empty Eildon would not trigger the desal. Why would it? The desal makes drinking water, Sugarloaf holds non-drinking water (it needs treatment to go into the drinking storages ), Sugarloaf is where the never used pipe connects to the Goulburn. The reason Eildon runs low is it is an irrigation dam. The water rights are sold, all down the massive Goulburn valley. When it doesn't rain as much as the water rights demand in terms of flows, the level goes down. It had gone down ever since 2012, progressively a bit lower each year. There was hardly any filling in 2015, the spring was dry. You might think it rained a fair bit but it takes enormous rain to fill Eildon. If there had been a couple more dryish years Eildon may have gotten to low 10s of %. I think before the drought broke in 2010 it was down to below 10%, so it does happen. But it's designed to do that! If it was constantly in the 80-100% range, on the one hand that would be great, on the other hand you'd have to wonder why you built such a large and never-used capacity. Also, it needs to be able to fill - it's got more storage than will be used this year when it almost certainly won't fill!!! Fact is, in hot summer times the outflow is typically 10,000 ML/day. That is only exceeded by significant rain events even in winter. Typical winter flows with fronts dropping 10 cm snow and equivalent rain through the catchment regularly won't get the inflows to the lake above 10,000 ML/day. Inflow Monday 17/10 9 am after an inch of rain.... ~ 5,000 ML/day (I checked). That's why she empties....
Also, the outflow all winter is negligible - 130 ML/day which is just enough to keep the ecosystem going before the river channel gets topped up by Snobs, Rubicon, Acheron etc... They really keep virtually everthing they get from the catchment, through winter. One summer day of irrigation flow would roughly equal a whole winter's riparian flow...
Yup. Good summary
The data reflects what you said.
2013 saw a pretty decent winter and spring, so Eildon was full. 2014 wasn't quite as wet, so it reached around 90% But 2015 was a dry winter and spring, and the dam fell to less than half full on the back of that. It was the same at Dartmouth in 2015 - a slow and steady decline in storage.
Every time I see the name of that lake I get a Karnivool song in my head..
Latest BoM has minor flooding upstream of Hume. With flow at Jingellic only 1/3 of 10 days ago the MDBA "should" be able to manage this and only cause minor flooding downstream without having to open any spillway gates. Hydro and valves should be enough. Let's see. Of course hindsight is wonderful and if they had pre- released say 500 GL a month earlier then Deniliquin would not be in its current dilemma... W