The problem with growing cotton and rice, among the worlds thirstiest crops, is that except during times of drenching rains their production means that other users of water in the Murray Darling basin have to reduce their consumption.

We have all heard the complains of NSW and VIC irrigators that the water consumed by Queensland growers means less water river water for them. Using 1,000 gigalitres to grow rice during times of water scarcity has its effect on others.

Over-allocation and lack of balance between agriculture, urban populations and the environment, not just in Queensland or Victoria but throughout the basin are unsustainable, particularly when climate change produces drier conditions.

Business as usual is not an option. If it were, we would soon find ourselves with a river basin that was drying and dying and unable to provide irrigators or towns people with the water they need.

Water allocation reform, more efficient use of water, improved storage and tackling the problem of evaporation are all stop-gap measures which can and should be taken while we studiously ignore the root cause, global warming and its effects on our climate.

Agnostic, sorry old chum, the root cause is basically over allocation. This is compounded by other factors such as the inefficient use of the water, lack of recycling urban water supplies, the ever increasing need to grow food for an ever increasing population, the list goes on, but the basic problem is over allocation. If it's not there, you can't have it, end of story.

David

VK3AUU says … if its not there, you can’t have it
Quite right! But why is it not there?

Torrential rain this year and the drought is broken and very nice too. But the longer-term outlook is for drying of the southern part of Australia, based on predicted effects of global warming. And if that is not tackled it does not matter how well we reform allocations, use of water or limit its loss through evaporation. We need international cooperation on tackling global warming or else face the prospect of having insufficient water to allocate, use and conserve.

You won't get any disagreement with me there.

David

About 10% of runoff in the Northern cotton valleys will make it to the Murray mouth under natural conditions. Obviously none in a drought, but relatively constant in normal and big flows.

What this means is that a large amount of economic activity can happen without the severe evaporation and soakage losses along the way. Water purchased in the Gwydir Valley for $2400/ML last year by the govt equate to $24000 worth of Murray entitlement, and if you factor in our reliability at the average 40%(18% last 10 years)it would cost the govt the equivalent of $60000/ML of entitlement per reliable ML at the Coorong.

Starving water from the Northern Valleys is not the answer to the Murray irrigators. It's not economic and it's not a fair sharing of resource.

For a comparison of water consumption:
http://www.abs.gov.au/ausstats/abs@.nsf/0/E08CBF7F165B2CC3CA2574A50014D2F5?opendocument

I'm told the 6ML/hectare we apply to cotton is the same as people apply to their lawns. Evapotranspiration at work.

Graham has picked up on an important aspect that Rice growers only get to use water when there is abundant supply. We don't have a consistent supply in our country of feast and famine. Annual crops like cotton and rice respond quickly to avaialable supply. Oranges and almonds don't.

And so lies the "over-allocation" issue. Without entitlements in excess of average availability, big water years would not be able to average out the poor ones.

many of the technical issues can be addressed

evaporation on water storages can be dramatically reduced

at least 2 australian companies have products that reduce evaporation by at least 75%

however the fundamental driver of water shortages is population growth

the first law of sustainability (Dr. A Bartlett )

" Population growth and/ or growth in the rates of consumptionof resources cannot be sustained "

"17th law : If, for whatever reason, humans fail to stop population growth and growth in the rates of consumption of resources,Nature will stop these growths "

" 19th Law: Starving people don't care about sustainability."

" 21st Law: Extinction is forever."