PUBLIC WORKS: by Peter MillingtonNews Weekly
The urgent need to build new dams
, March 5, 2011
Australia's recent weather extremes of droughts and floods have highlighted the urgent need to build more dams, says Peter Millington, a former commissioner of the Murray-Darling Basin Commission.In the years ahead there will be tens of thousands more people living in the Murray-Darling Basin with more advanced lifestyles and water needs, more industry and bigger urban centres.
There will be bigger cities outside the basin demanding higher food production, and a world food need that almost demands that Australia ups its production from its vast land resources. Improved technology and water efficiencies will help, but one can only "squeeze the lemon" so much to achieve water savings and this will not meet future demands.
So why are dams seen as such a "no-no" by so many? A lot of this is due to misinformation and confusing Australia's position and experience with overseas examples of "poor dam-building".
It is true that many dams around the world have been poorly conceived, single-purpose projects that have given little or no consideration to environmental or social aspects. Environments have been destroyed and thousands of people displaced without proper compensation or assistance.
This is not really the case in Australia. Resumption of property and social issues are well managed by law, and environmental issues with any recent dam over the last 15 years have been very stringent.
Old dams are continually being modified to provide better flow release patterns for the downstream environment, as are operating rules to take better account of downstream issues. Valley water-sharing plans now place strong requirements on how dams are managed, so it is quite incorrect to say in Australia that "dams are bad" per se.
Our rivers are so variable in annual flow that we just can't rely on the irregular stream flows to meet present and expanding needs. (See the accompanying table for an idea of the magnitude of this variability.)
Dams are needed to "smooth out" this variability - capture high and flood flows for later use during extended dry periods.
Sydney would only have 250,000 people if it had to rely on run-of-the-river water instead of its network of headwater dams, while Brisbane would have been much more severely flooded if Wivenhoe Dam had not existed.
This does not mean that we should build more dams for agriculture, even though this should not be discounted. For example, where soil types and tropical agricultural practices permit extensive development in Australia's north (and it is hard to believe that, with care, this is not possible), then water storage will be needed, which means more water conservation dams to feed crops in the dry season.
There should be no barrier to this being studied and the best option developed. There should be no pre-judging of the dam issue here, surely. There is too much opportunity for Australia to do its obligation towards meeting world food needs.
Elsewhere, in the Murray-Darling Basin, it is unlikely that new dams would be built to expand irrigation areas; the best "irrigation dam sites" have already been developed.
But there is no reason why planning won't uncover a range of possible dam options that could collect the higher portion of flood flows (once the acceptable environmental needs of the basin are met), and these could be used to provide environmental flows and reduce the need for water cut-backs from irrigation, or add to environmental flows during dry periods, or to help consumptive-users work through long drought periods by providing back-up allocations in key years.
The money that governments spend on drought relief, and later on structural adjustment, could perhaps be better used by funding these "high-flow storages" and creating greater security for existing irrigation and environmental health.
There has certainly been plenty of surplus water in parts of the Murray-Darling Basin over the last month or so. Could some of this be sensibly stored for later effective use?
Proper long-term basin planning doesn't preclude any idea or concept without proper evaluation and long-term assessment of pluses and minuses - even inland diversions from coastal streams should not be automatically rejected without study. There are both flood mitigation benefits and water diversion benefits to be assessed. We have seen major flows recently in the Clarence Valley that could be considered surplus under any reasonable assessment.
And then there is the oft-quoted contention (by the anti-dams groups) that new dams would never fill.
If we accept that any new dams in the Murray-Darling Basin will be more for drought security for existing development and/or for augmenting environmental flow needs, then we are looking at storing the infrequent very high flows that would be surplus to environmental needs.
Well, would such surplus flows really occur? Tony Weber, a hydrological consultant and visiting fellow at the Australian National University's Integrated Catchment Assessment Unit, estimates that in just 72 hours the skies above southeast Queensland unleashed an astonishing 6.5-7.5 billion tonnes of water on to the ground below. This was equivalent to 12-15 Sydney Harbours, or more than four Sydney Harbours a day.
Were Queensland's planned desalination plant at Tugun to get up and running and produce its maximum capacity of 133 megalitres of drinking water a day, it would take more than 150 years to match the amount of rainwater that fell into southeast Queensland's catchments in early February. And of course, there were also record floods in Victoria that clearly generated "surplus flows".
So, yes, we do need to understand that the environment needs high flows as well as low and medium flows, but we must also accept that there are such things as "surplus flows"; and if studies show that it is sensible and rational to store and later use some of these waters, then so be it.
So this continuous chatter about further dam-building being a disaster should be put in perspective - future dams should be on the planning agenda just as much as any other planning aspect.
If a 20-year or longer term need is best satisfied in some way by building a new dam, then this is how it should be - but with all the social and environmental constraints deemed necessary.
It is just plain stupid to pre-empt good long-term water-planning work by some initial prejudice that rules out dams because someone perceives them as "nasty".
Here are some additional points to bear in mind on Australia's long-term water needs:
• We rely on agriculture (food/fibre) in the Murray-Darling Basin to satisfy about 75 per cent of domestic consumption - much more than earlier thought.
• To take 40 per cent of water away from agriculture and give to the environment will have major impacts on food supplies and security.
• To do this without proper, open scrutiny of the science and the environmental health, and without proper consideration of the immediate socio-economic impacts, is fraught with danger for our economy and lifestyle.
• To undertake this planning by giving priority to environmental needs, and not by seeking to achieve a "balance" between social, environmental and economic outcomes, defies international best practice, and, despite the views of the green lobby, actually reverses earlier achievements in the Murray-Darling Basin.
• To do so without proper community consultation is both ignorant and arrogant.
• To do so without proper consideration of 10-, 20- and 50-year scenarios is narrow and lacks vision for the basin and its communities.
• To do so by ignoring the role of future dams for drought security and environmental flow improvement indicates a profound failure to understand the highly variable nature of our rivers.
• The Commonwealth-inspired Water Act and the new Murray-Darling Basin Authority (MDBA) cannot support and undertake "integrated river basin management" (IRBM) in a way that will overcome these deficiencies in planning approach.
• Communities and industry must do a great deal more to make Commonwealth and state governments aware of these deficiencies and demand action to allow proper management of the Murray-Darling Basin.Peter Millington was director-general of the NSW Department of Water Resources (1987-95) and former commissioner of the Murray-Darling Basin Commission (1987-96), and has been an international water management consultant to the World Bank, the Asian Development Bank and many other international aid agencies. The above article is an extract from the paper he delivered at the National Civic Council's national conference held at Mannix College, Monash University, Victoria in February, 2011.