The journal Climatic Change has published a special edition of review papers discussing major natural hazards in Australia. This article is one of a series looking at those threats in detail.
Droughts are a natural feature of the Australian environment. But the Millennium drought (or “Big Dry”), which ran from 1997 to 2010, was a wake-up call even by our parched standards.
The Millennium drought had major social, economic and environmental impacts. It triggered water restrictions in major cities, and prompted severe reductions in irrigation allocations throughout the vast Murray-Darling Basin.
The Millennium drought also highlighted that, compared to the rest of the world, the impacts of drought on Australia’s society and economy are particularly severe. This is mainly because our water storage and supply systems were originally designed by European settlers who failed to plan for the huge variability in Australia’s climate.
Have we learned the lessons?
Are we likely to fare any better when the next Big Dry hits? It’s important to reflect on how much we actually understand drought in Australia, and what we might expect in the future.
Our study, part of the Australian Water and Energy Exchanges Initiative (OzEWEX), had two aims related to this question. The first was to document what is known and unknown about drought in Australia. The second aim was to establish how Australia’s scientists and engineers can best investigate those unknowns.
The fact is that despite their significance, droughts are generally still poorly understood. This makes it hard to come up with practical, effective strategies for dealing with them when they strike.
One reason for this is that unlike natural hazards with more graphic and measurable impacts (such as floods, cyclones, and bushfires), droughts develop gradually over huge areas, and can last for years. Often they go unnoticed until they trigger widespread water or food shortages, or cause significant energy, economic, health or environmental issues.
Bidgee/Wikimedia Commons, CC BY-SA
Drought has been described as a “creeping disaster”, because by the time a drought is identified, it is usually already well under way, the costs to fix it are mounting, and the opportunity to take proactive action has already been missed.
This is complicated still further by the uncertainties around defining, monitoring and forecasting drought – including predicting when a drought will finally end. As in the case of other natural hazards (such as drought’s polar opposite, floods), what we need most is accurate and practically useful information on the likelihood, causes and consequences of droughts in particular areas.