Flood Information and River Conditions

VK3YNV

Administrator
Staff member
The automated data collection systems for river heights is available here..


The river heights don't translate directly into flow rates for predicting flood peaks. The critical data required is flow rate vs river height at the monitoring stations, further, the timing of peak flows downstream is a non-linear function, at flows below a certain level the rivers follow their normal meandering course, but as the river height increases the rivers start taking shortcuts across the meandering loops, thus making calculation of timing for major flood flows a problem.

The computer flood modelling these days takes account of these factors, and still should be a reliable guide to estimating peak levels and timing.

If you are in a flood prone area, now might be time to stock up on essentials.

Some usefull websites..
General Information :- https://www.abc.net.au/emergency/
Road Closures :- https://traffic.vicroads.vic.gov.au/
Vic Emergency :- https://emergency.vic.gov.au/respond/
 

BillC

Active member
We also have a lot of grass cover at this time, so that would spread out the water flow rate and peaks over perhaps a longer period of time? On my paddocks here there is a lot of water being stored. Some drainage lines have up to 100mils of water moving slowly through the grass.
 

VK3YNV

Administrator
Staff member
Good point Bill, the ground conditions affect not just the amount of run-off, but also the rate of run-off.

This is the River height of the Yea River at Devlins Bridge.
IDV67208.088125.png
 

BillC

Active member
Very interesting. The Honeysuckle Creek at the bridge near us has been at a nearly constant level about 2.5m below the beams for the last 20 hours or so. The channel capacity has been able to handle the inflow rate over the relatively long period of time. The rainfall here has been constant and gentle, no heavy peak falls of rain. However there is still a lot of water in the system so expect flooding on the lower parts of the catchment (Shepparton).
 

VK3YNV

Administrator
Staff member
The 1974 flood peak in Seymour was 7.64, based on current trends it looks likely to exceed that, earlier today the official forcast for the Goulburn at Seymour was 7.7

IDV67208.088126.png


Edit: 7:30PM Thursday Reached 7.79 and still hasn't peaked.
 
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VK3YNV

Administrator
Staff member
Let's hope there is plenty spare capacity in the Nagambie weir!
Interesting thought, but the Goulburn Weir capacity is just 25,500 Ml and it's currently 95% full, the peak flows in the Goulburn will be around the 100,000 Ml/day, so the flow rate in the river would fill the Weir (starting from empty) in just a few hours.

On the other hand, if they quickly open the gates and try and drain it as much as possible before the peak arrives from upstream, then close it up quickly and try to use it to slow the Goulburn peak when it arrives.
Of course that could make things worse downstream, if they slowed the peak in the Goulburn and it then happened to co-oincide with the peaks in either the Seven Creek or the Broken River.

Best strategy for Shepparton is to stagger the peaks so they don't co-oincide. :) Tricky..
 
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BillC

Active member
I reckon most of those in charge are not game to "pull the lever", in case of recriminations, just leave things alone,,," Well it waas beyond our control" Both the Broken and the Sevens catchments are really loaded. The Sevens is a smaller catch. and the Broken much bigger so I suppose that the flood peak would be spread out over a considerable time.
 

VK3YNV

Administrator
Staff member
Funny thing, I think they are actually doing exactly that, the weir level has dropped sharply over the last few hours. Every little bit helps.

Goulburn_Weir.png
 

VK3YNV

Administrator
Staff member
The Goulburn at Seymour peaked about 3:00AM at 8.26 meters, ( 0.62 above 1974 flood level) so that means at least 12 meters in Shepparton without any contribution from the Seven Creeks or Broken River. The river height at Murchison will be a more accurate indication of peak flows and timing. Early indications are it will come close to or exceed 1974 levels.
 

VK3YNV

Administrator
Staff member
Good luck Ray.
Thanks Bill, Josh and I spent today helping my daughter get prepared. She goes under at 11.7 meters, and we are currently expecting 12.2 or above.

310358789_10159351121469779_5518051887835707707_n.jpg


We sealed up the vents and windows and tomorrow morning we will do the doors. Fingers crossed
 

VK3YNV

Administrator
Staff member
Interesting bit of random trivia, the peak flow expected in the Goulburn equates to approximately 3000 tonnes of water per second. Or if you prefer the universal measurement system, 15 blue whales per second.
 

VK3ZYZ

Moderator
Staff member
It's just as well that whales are mammals otherwise I would think that measurement pretty fishy!
 

BillC

Active member
Wonder of all wonders , How can all that weight of moisture be supported in the sky? well it can't. It falls out as rain. Seriously what an amazing process!
 
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