Droughts and Flooding Rains

Monday 03 November, 2008


Droughts and Flooding Rains”- and not much in the middle.
A trip by road across Northern NSW last week and a flight in a light aircraft over the flooded Warrego, Paroo and Cuttaburra Creek, reinforced how Dorothea Mackellar got it so right. Australia is indeed a land of massive variability with quite extraordinary recuperative power.

Country that only a few months ago looked like the face of the moon after the worst drought in Australia’s short recorded history and from which many said it would take years to recover, now looks magnificent. Waving natural perennial grasses, in some cases literally up to the top of fences, has replaced the bare dirt. The seedbed in this country must be huge. Depending on soil temperatures when water is added particular seeds germinate and dominate. Wetlands spring to life and areas like the Cuttaburra Basin have to be seen to be believed. Tens of thousands of acres covered in shallow water from the western Queensland rains. Bird life is fabulous although an encounter with a flock of pelicans heading west at 5,500 feet can give some anxious moments in a little aircraft. How do they know where the water bodies are? Better still, the lift in country people’s spirits after seven long years of drought1 is truly remarkable. It may not rain dollars, but it certainly rains hope, joy and confidence.

A week later we find the metropolitan press having a field day with negative propaganda from the likes of Professor Richard Kingsford, a well-known bird lover (nothing wrong with that), who has for years viewed irrigation as the root of all evil. Kingsford maintains a constant vendetta against man’s activities without ever recognising the social and economic benefits that can be derived from conserving a portion of our massively variable rainfall without inflicting unacceptable damage upon the environment.

Whilst it would be easy to become paranoid, it is truly alarming to see the lowest rainfall and run-off in our recorded history2, not being accepted as the primary cause of drastically reduced river flows. There must be something in man’s psychological makeup that makes it much more satisfying to blame human activity for what are predominantly natural events.

We seem to hear nothing but total blame for the low flow levels in our rivers being attributed to “irrigation extractions and mis-management”. We even have new members of parliament stating in their maiden speeches that one of their objectives is to “fix our rivers”. As though all we need to do is to reduce extractions. The dynamism of our rivers and the fact that water flows away and needs constant replenishment if flows are to be maintained, seems to escape most commentators, including some leading scientists.

Malcolm Turnbull has used the analogy of a bathtub to explain this widely held misunderstanding. People seem to view the rivers as a stationary tub that continues to hold water providing it is not bucketed out. The true analogy is, of course, a bathtub with the tap running and the plughole open. Some extractions will reduce the out flow (and this is what needs to be regulated), but whilst the tap remains “on” (read rain) the tub will continue to carry a stream. Our problem of the last several years has not been extractions from the moving bath flow, but the fact that God turned the tap off!

In fact, over the last several dry years, if in NSW there were no dams in the hills which feed our western and south-western flowing rivers, and thus no irrigation, the flows in our rivers would have been worse, sooner. The impact of the dams is to spread the flow time wise and keep it running for longer.

Australia’s rainfall and run-off variability is notorious. The Darling River at Bourke, with its enormous northern and eastern catchment, has an annual average flow of 2.5m.megalitres. The spread around the average is huge. It ranges from zero (i.e. no flow whatever for 12 months), to 12m. megalitres (24 Sydney Harbours). If man is to live and prosper with this enormous variability, which the climate change scientists tell us is going to become even more variable, then two principles need to dominate our thinking. We need to conserve in times of plenty and build flexibility into our planning.

Conservation can take many forms, for farmers it can mean saving cash, saving feed (ground cover, grain and/or hay) and it can certainly mean conserving water.Take for example the recent very damaging NSW North Coast floods and think about the fact that we did not conserve a single megalitre. After such a dry period, surely an indictment upon this generation.

Some water stored high in the mountain catchment could have mitigated flood damage and provided water for future use on either side of the mountains. We are not talking about diverting rivers, rather we are suggesting water conservation that reduces flood damage and accepts our need to live with rainfall variability.

Flexibility can be achieved in many different ways. As has recently been recognised by the likes of Professor Peter Cullen, the growing of annual crops like rice and cotton, as distinct from permanent plantings, can mean that when water is unavailable no crop is planted. These crops are thus well suited to our variable river flows. (Cullen previously stated that “in a dry country like Australia we shouldn’t be growing thirsty crops like rice and cotton” and this statement has been “parroted” across the country, particularly in our cities.)

We clearly need more dams to put the conservation principle into practise. Given its long-term impact such expenditure can be amortised over very long periods. These dams need to incorporate large outlets to let small and medium flows pass when there are real downstream needs. Thus further applying the flexibility principle.

Given the massive variability of our rainfall and run-off patterns, it is extremely difficult to codify in black letter regulation, rules to deal with all eventualities. Rather our rivers need to be managed “adaptively” taking account of the massive variability, and balancing the often competitive social, economic and environmental needs.

It certainly makes little sense to deal in absolute whole numbers (e.g. the Murray Darling Basin Cap) when there is such huge variability. Rather the control mechanism should surely be based on variable percentages of flows rather than fixed numbers.

In fairness to our regulators, the “cap” was never intended as a long-term measure, but rather it was a short term initiative to gain some “breathing space”, whilst longer term measures were devised and introduced. However, as with many temporary taxes, they have a tendency to become fixtures!

Rural and regional Australia needs employment creating industries. Economically sustainable industries suitable for remote areas are difficult to identify. On our inland river floodplains, irrigation is a natural, if secure water can be added to complete the mix of excellent alluvial soils and ample sunshine.

This particularly applies if we are going to improve the living standards of indigenous Australians. It has been demonstrated that, self-respect, behaviour and health all improve where regular employment is available and taken up.

Thus there can be very considerable national savings as people are freed from their dependence on welfare and these savings should be factored in to the economic justification for water conservation investment.
David Boyd
For accompanying photos view http://picasaweb.google.com/davidboyd11/BackInBusiness?authkey=IPOIyT8cjXs

1] The immediate Bourke area of the Bourke Rural Lands Protection Board was drought declared in August 2001 and the declaration was not lifted until February 2008.

2 “The two year period to November 2007 recorded the lowest ever inflow to the Murray River. Inflows during this period were 43 per cent lower than the previous record low, which occurred at the end of 1938.” Prime Minister 04.03.08

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