Salt Question

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Rob
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Post by Rob »

There are maps here to boggle the mind, historical rainfall, ground water, averages, evapotranspiration, ground water recharge etc etc.

http://www.water.gov.au/maps/index.aspx?Menu=Level1_8

Cheers,
Rob
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Post by DLRA »

Rob wrote:
David Leikvold wrote: I wish we had an OS map of the state so we could see which way surface water flows.

Surely the Dept of Water Land and Biodiversity Conservation would have one? (Say that 3 times fast!).
I trawled online and came up with:

http://www.asdd.sa.gov.au/asdd/ANZSA1024000017.html

and

Contact information
Contact organisation: Department of Water, Land and Biodiversity Conservation (DWLBC)
Contact position: Manager Water Information
Postal address: GPO Box 1047
Locality: Adelaide
State: SA
Country: Australia
Postcode: 5001
Telephone: 08 8463 6975
Facsimile: 08 8463 6999
Electronic mail address: Walker.CraigM@saugov.sa.gov.au

Cheers,
Rob



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Rob
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Post by Rob »

Greg,

Am I correct in saying substantial rainfall within XII (Western Plateau) will affect Lake Gairdner? or?

I was looking for a basic map that showed rainfall from "A" flows to "B" etc and thought that one only showed managment areas?

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Rob
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Post by DLRA »

The Lake Gairdner catchment is only area 1 (Gairdner) within the Western Plateau Division.

I had a go at overlaying some of this data. See here;
Image

What I want to do next is overlay the topographic data on the catchment as well as locate Nonning and Womera weather stations. Then we're really starting to define our climate.
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Rob
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Post by Rob »

You may already have this Greg,

http://www.atlas.sa.gov.au/go/mapviewer ... opographic

You can turn on and off quite a few layers or localities along with land features, boundaries, borders, vegetation etc etc. one that caught my eye was weather stations.

Takes some messing around to add / remove layers and get them turned on.

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Rob
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Post by DLRA »

Thanks Rob,
Good find, well done.
Geographic Information Systems is what I used to do for a living and am still involved with, especially deploying online. The guys in SA were early adopters and I have been over a couple of times with work. I've also just been able to get some of the base data sets so am looking forward to being able to make some pretty maps when all this settles down again.
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BOB ELLIS
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Post by BOB ELLIS »

Greg , Expect a call from me tomorrow (Thur 14th) Cheers , Bob #66 C/GCC.
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An experiment

Post by hawkwind racing »

I conducted a backyard experiment over the last couple of days ,trying to simulate a rising water table , I used my 2000 vintage souvenired Gairdner salt sample ,its dimentions were roughly 150mm x 200mm x 25mm ,it was hard but not concreate hard due to the rain and high humidity locally ,I placed the salt into a fine mesh colander then placed the colander into a larger pan , I added water untill it just covered the top of the salt and let it sit undisturbed, I checked it aprox every 12 hours testing its hardness , after aprox 48 hrs the salt was soft enough to push a tooth pick in with ease and after aprox 60 hrs it was mush like a semi liquid , this afternoon i raised the colander above the water level , the water drained from the salt rapidly leaving the salt the consistancy of wet sand and very soft , I will now monitor how long it takes to become firm ,then hard ,I predict it will take a while under the temp and wind conditions locally ie cool and low wind speeds
the experiment shows that subjected to a large liquid body the hard salt becomes very soft quite quickly ,I also believe that the thicker the salt the longer it takes for the softening ,I will also speculate that after the major flooding of the lake in 2006 which left a mud/silt covering over the thick hard salt ,we now have a much thinner layer of salt over a mud base and when this thin crust is subjected to sitting water ,either on top or from underneath (rising water table ) the salt becomes very soft ,also the professor that responded to some questions in this thread said water near the surface when heated by high temps expands and rises to the top of the salt causing softening ,he also believes that the lake will take a long time to heal ie build a thick layer of salt over the mud /silt and this problem may persist for years to come ??? we should take some core samples so see how much salt is above the mud and monitor to see if the moon /tide cycle does actually affect the hardness of the lake
cheers
Gary the mad backyard scientist
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good work

Post by Dr Goggles »

if only we had more like ya Gary :wink:
...few understand what I'm trying to do , but they vastly outnumber those who understand why..
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more experiments

Post by hawkwind racing »

I have extended my madness to some further experiments , while the salt dries out I am taking conducttivity/ resistance measurments and classifying them under my own system , using one of my multi meters I have gathered the following data
measurements taken with meter probes at 25mm apart and probes inserted aprox 10 mm

saturated saline solution @20*C = 15K/20K ohms
decription = salt soup with visable water on surface

Very soft /wet salt @ 20*C = 35/45K ohm
decription = water pools when presure applied to salt

very soft salt @20*C = 140/150K ohm
decription = water does not pool when pressure applied

more to follow when the salt dries further

Also another idea to measure the water level /table below the salt , drill a 25/50 mm hole into the salt say up to 500 mm deep and then place a plastic conduit into the hole ,you can then monitor the water level in relation to the salt surface
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Post by momec »

You've got a great point among others Hawk about core samples.

At the moment we are only looking at the surface and poking at it with sharpened objects. A proper core sample would answer if the big influx of mud was still there causing us grief or has sunk to the bottom.

Wet is wet and only time will dry it but the theme here is understanding the beast.

Cookey or OT any thoughts?

Chris
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Post by internetscooter »

I've had no response from the Lake Tyrell research guy - and my googling comes up that it is a completely different basin (which I gather means the water catchment area). I've contacted a Geospacial guy at RMIT (satelite imagery/analysis) and his understanding...

"I think the cycles have a high degree of variability, so 'science' may not help that much"

Someone DLRA should officially contact http://www.parks.sa.gov.au (which I don't mind doing) and see if there is some information we don't know about.

They have this info (see Geology and Landform) (Note also DLRA are considered of "special value")
http://www.parks.sa.gov.au/publish/grou ... ner_mp.pdf

Which basically states - water is localised, small creeks and direct rain fill the lake. Salt comes from ground water. "... probably in a majority of years, Lake Gairdner holds surface water during the winter/spring months from August to October."

If the DLRA is of "special value" maybe we can request a weather station out there if that what it takes to get better at predicting conditions.
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Post by internetscooter »

More Salt Info…

Additional info from talking to an Adelaide friend who is a Sustainable Agricultural Systems Consultant (someone that consults to farmers on how to manage their land)…

Here’s some more info on how the soil moisture system works.

Short Version: Soil profile and water table combinations will affect salt behavior greatly due to a little bit of moisture causing even more moisture from ground water to be sucked up.

Long Version:

Over the wet season the soil gets moist and the water table rises. During the dry season the soil dries out and the water table falls proportionally. This could be complicated though by salt sealing the surface and reducing the drying out effect below it (he isn’t a salt lake expert, so isn’t sure).

A good and predictable race condition is when the soil dries out thoroughly and the water table is low.

A bad race condition is when the water table is high, even just a little bit of rain will cause the top layers to moisten and a capillary action can occur where the salt/soil draws up water from the water table below.

By his opinion, to get a good understanding of race conditions we’d need the following:

Core test every ~1km along the track:

This gives us an understanding of the texture of the soil at different depths. With this we get an Electrical Conductivity profile, which is a predictor of capillary behavior of the soil.

Water table depth:

This tells us how close the source of moisture is to the surface compared to the soil capillary profile (i.e. when we have to worry about capillary action occurring)

Humidity pattern of the area:

This tells us the conditions when moisture is evaporated or not. Above a certain humidity value the soil stays moist.

Rainfall pattern of the area:

This tells us what moisture is coming from above and can help predict water table fluctuations.

He said that it shouldn’t be that hard to get some sort of grant to get someone to perform such a study as it is not that expensive (in grant terms). For example, core testing would be ~$2,500 (~$1000 for core sampling and ~$1,500 for core testing).
Paul
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Post by gennyshovel »

Well done internetscooter,
Your bloods worth bottlin'
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nice work

Post by Dr Goggles »

Good one.
'Scooter

In order to make our event more predictable, make the financial risks to supporters ( the emergency crews take holidays to participate)less and have more racing we need to understand how it works.

A scientific approach and the gathering of data will make that more likely , many hands make light work and so everybody who pitches in with a sensible idea and a little bit of legwork makes this all the more likely , it spreads the load and makes use of many talented people.

Gary's backyard experiments above might seem wacko to some....they are exactly what we need , a logical approach to measuring and estimating what we need to know......when will the lake be right for racing , how long will it take to come good , what conditions improve our chances and what conditions diminish them.

This website is an invaluable tool to a club that is spread all over the country as a way of recording information and sharing ideas. The office bearers of the club are faced with several issues at the moment and this one concerning the systems that affect the condition of the lake is one that this website can go a long way toward solving. If you are reading this as a lurker( not a regular contributor, or someone who isn't registered ) and you think you can help then now is the time to stick an oar in . Be it technical knowledge , a connection within a department who may have knowledge or the ability to help or any other method of advancing the bank of information your input is needed now.

Poor communication , sitting on hands or just hoping it will get better won't increase the chances of us racing , hoping someone else will do it or leaving it to the office bearers is just overloading people who are devoting a lot of their time for little thanks already....

This is a great sport , a great bunch of creative people we have a great website here.....we can do great things.
...few understand what I'm trying to do , but they vastly outnumber those who understand why..
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