One commentator on the topic, Associate Professor Willem Vervoort from the University of Sydney, writes:
‘Using dams to secure water supply for irrigation is similar to using a sledgehammer to kill a fly. Yes, it will kill the fly, but it is a fairly inefficient way of doing it, and you might destroy other valuable items on the way.’1
With last October’s agricultural green paper showing a firm emphasis on dams, it seems that we have forgotten to take into account what has been learnt from the past in the rush to build more dams for agriculture and industry. Two key elements that a dam needs – namely, a reliable inflow of water and a suitable landscape – are areas that the Australian environment has often been unable to provide.
And, with our lack of tall mountains and deep valleys, Australia’s relatively shallow dams are susceptible to high amounts of evaporation, with the surface-area-to-volume ratio determining how sensitive a dam is to evaporation. Our climatic conditions also tend to produce higher amounts of evaporation than in cooler climates, and thus more stored water is ‘lost’ to the atmosphere, and taken away from intended uses in areas such as irrigation.
Further disadvantages, such as unintended upstream and downstream effects, and the limited lifespan of dams due to sedimentation, add to the broader social, economic and environmental effects of diverting a river from its natural course.
1 Willem Vervoort, ‘Dams are not the smart way to secure water for agriculture’ in The Conversation.
Furthermore, it is still unclear how the relationship between dams, streams and rainfall will shift with climate change. These uncertainties are particularly acute in northern Australia, where water conditions are already highly variable because of tidal and monsoonal fluctuations.
We need strategies for water use and water storage that take into account the interconnectedness of the water cycle, and that can respond to environmental change within the context of a changing climate. In reality, this will probably equate to a mixture of solutions, including existing dams and other water infrastructure (for example, making use of groundwater, water recycling and desalination systems).
And, crucially, the water industry needs to maintain strong links to research departments whose work will be instrumental in revolutionising our water management systems, as well as influencing water policies to ensure that our water use is as efficient as possible. If Australia is to make good on its investment in water as a top priority for the future, we need to be developing and implementing smarter water management and storage systems.