Muddy Waters

ok, I'll have a stab at this...

i dont know for sure why it is muddy but thinking about how thhe red-dust penetrates everything i would say it is because of the fineness of the grains of dust - gets everywhere when it dry

It's to do with the presence of colloidal clays (and silts) which are so fine that they remain in suspension. Some coastal rivers eg Fitzroy River circa Rockhampton are permanently "dirty" because of the presence of this colloidal clay.

If the particles are fine enough they will not settle. There may be an ionic effect on waters around Lake Eyre due to the salt content. The salt could effect the charge of the colloids creating a floculant effect, though i'm not sure of the science involved in this location.

Hope that helps
Andrew

it's about soil sodicity, and clay dispersion

some good info here

Best regards, Peter

I am not an expert but I do know that if we had a dam that was very muddy we would pump in some salty water and it would settle. I expect this is the same with the central Australia rivers. They would be fresh and the coastal rivers would have a small amount of salt.

Neil

The salt acts as a floculant causing the fine silt particles to bind together forming lager particles which then sttle out a lot quicker, it can often be used to indicate if a water source is saline or fresh.
Mike

Gday,
Not Always?
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For this reason we carry powdered alum to use as a floculant to clear the muddy water, so that we can use it for washing clothes etc.

I am no expert but the rivers going into the Northern end of Lake Eyre are only muddy while there is fresh flood water or local rain feeding them then they go clear and salty. Also The Diamintina is a choky brown and the Erye Creek is milky brown, with different land systems you also get different coloured waters. The Derwent Creek feeds through the Sturat Stoney red gibber and when it feeds the Warbuton it is reddy brown.

The Battery man above is right- it's because of sodicity in the soil. At certain ratios of sodium ions (+1) to calcium or magnesium (+2) ions, the addition of fresh water can cause the fine clay particles in the soil to spontaneously disperse, giving muddy water. Sodic soil is very very common in Australia!