Wednesday, Jun 03, 2009 at 12:48
Ripped this from the following link:
http://www.lakeeyreyc.com/fldhist.html
Most Flood Level Reports are Wildly Innaccurate
Lake Eyre has some water in it more often than many would lead you to believe. When Halligan flew over the Lake in the 1920's and reported it as being about one third full he was ridiculed by seasoned
explorers.
Today we have similar situations where land based observers can't believe the dry Lake they are looking at contains water and airborne observers are claiming that the "Lake is the fullest it's been in years". Quite often they are both wrong!
Why:
Most people who travel over land to view the Lake arrive at a point on the Lake where it is shallow and often dry, for example
William Creek to
ABC bay, or arrive at a basin that is not currently flooded, for example Madigan Gulf in a
Warburton flood.
Aerial observers, especially in a floods initial stages, see the sky reflected across the entire wet surface of the Lake and claim it is "full". Most of this water is very shallow, say 10mm deep, and still FLOWING to deeper parts of the Lake.
Of course the tourist industry would prefer the Lake to be full for only the second time this century every year. The possibility of any water being in the Lake generally causes a flurry of exagerated claims to reach an ignorant city based media. Roll out some file footage and you've got a story.
Reliable Information From Satellite Images
In the early days the Commodore was faced with the difficulty of deciding if the 3000km round trip would result in a successfull sailing adventure. Phone calls to locals, rangers, policemen, publicans and pilots gave wildly conflicting reports. Their report was based on limited personal observation and heresay - a more reliable method was required.
Landsat satellite images available from the Auslig web site
http://www.auslig.gov.au were proven to be the most reliable way of determining these parameters. Of course the images were first "calibrated" using published depth diagrams checked by actual depth measurements on sailing trips. Experience has shown depths can be estimated within 100mm in the navigation critical 1 to 3metre depth range.
With experience water proximity to certain features in the Lake can quickly indicate depth. Recent local rain can make the whole Lake appear dark and give a misleading indication of depth. A more accurate reading can only be made when the Lake is either white(or light blue) salt where dry and dark blue where the depth is greater than 50mm.
Water inflow is crudely, but interestingly, represented by the units 1-3 for each source. 1 = minor flood, 2 = moderate and 3 = overflowing the bank. The units (Floodges) add to produce the coloured bar graph. The colours indicate the source - reds the
Warburton, yellow the Cooper, blues flow into LES and the greens the western creeks into LEN. An observation being that local rains comtribute to navigable floods more than may have been previously thought.
AnswerID:
368244
Follow Up By: Member - Footloose - Wednesday, Jun 03, 2009 at 14:12
Wednesday, Jun 03, 2009 at 14:12
Thanks, Terra, there are some interesting points there.
I wasn't saying that there isn't any water in Lake Eyre; just that for the average tourist even a flight isn't going to show very much.
FollowupID:
635808
Follow Up By: Crackles - Wednesday, Jun 03, 2009 at 17:29
Wednesday, Jun 03, 2009 at 17:29
"Most Flood Level Reports are Wildly Innaccurate "
Funny you should copy that report from the
Lake Eyre Yacht club as members of that very organization at
William Creek were only just a few weeks ago still spruking that Lake Eyre South was going to fill next month & expected to be able to sail their boats! In the next breath they were looking for donations towards the club :-) Talk about a beat up for financial gain. On a Jeep
forum one guy who took a 2 hour flight over the lake recently was dissapointed to see a total of only 10 birds.
Then again no one should be too surprised. Early on a couple on here (ExOz)were reporting that the Lake wouldn't fill this year & that there would be very little to see particually from the ground. Oh
well maybe next year.
Cheers Craig...............
FollowupID:
635827
Follow Up By: Bob the - Wednesday, Jun 03, 2009 at 21:18
Wednesday, Jun 03, 2009 at 21:18
G'day everyone,Recently returned from Birdsville/Eyre creek trip,plenty of birdlife to be seen on the creek if your quiet, as for the flights over the lake,
well was told at
all places I stopped to ask about the flights the pilots are not allowed to disturb the birds are while they are nesting...
FollowupID:
635886