Water Journal : Water Journal December 2014
DECEMBER 2014 water 25 Feature article T he Agricultural Green Paper released in October 2014 proposes 27 new water and irrigation projects, which the government claims will be necessary for Australia’s agricultural expansion. The emphasis is firmly on dams, with Federal Agriculture Minister Barnaby Joyce arguing that “water is wealth and stored water is a bank”. Joyce also implied that dam-building has hit a slump, blaming the environmental movement’s hostility to dams. But how do the new projects stack up to Australia’s dam-building past? And are they what Australia needs in the future? The proposed dam and irrigation projects are divided into three categories: six projects being considered for capital investment in the next 12 months; four more being considered for later investment; and the remaining 17 whose feasibility is yet to be confirmed. Only 14 of these 27 have storage capacity estimates, and at least two are expansions of existing dams. The future for dams is far from clear, but in the meantime perhaps we can learn some lessons by looking to the past. Dam useful We have always needed to store water beyond what can be naturally sourced at any one time, and stopping the natural flow of a river has proven to be the most effective way to do this. From ancient structures, to improved medieval designs, to today’s massive structures, the science has grown ever more sophisticated. Regardless of their design, the purpose of dams is usually a combination of agricultural, industrial, or domestic water supply; hydroelectric power generation; and flood mitigation. Stopping or impeding the natural run of a river can create social, economic and environmental impacts. That means that any touted benefits must have a clear economic and water-management rationale. ausTralia’s Dams: a poTTeD hisTory Australia has a long history of dam building, albeit with considerable variation in intensity. Our biggest single effort was the Snowy Mountains scheme, one of the largest hydraulic engineering projects of its day. Elsewhere, projects have been more modest. Dams need reliable water inflows, suitable landscapes to create a reservoir, and water users either near the dam or downstream. Australia has plenty of potential water users, but has typically fallen down on the first two considerations. As a result, Australia’s rapid rise in dam construction from the 1960s to the 1980s petered out in the 1990s (although so did the worldwide trend). As dam construction has faltered, overall water storage capacity has flat-lined, within Australia and elsewhere. This is not necessarily through a lack of will. It may be that given the ingredients required for success (inflow, landscape and customers), Australia is simply running out of feasible locations for new dams. DAM HARD: WATER STORAGE IS A HISTORIC HEADACHE FOR AUSTRALIA Are more dams the answer to Australia’s water security? Some say yes, while others adamantly disagree. Joshua Larsen, Badin Gibbes and John Quiggin, from The University of Queensland, addressed this contentious issue in this article published in The Conversation. 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year of completion Year of completion Global large dam construction (1900-2010) Large dam construciton in Australia (1900-2010) No.ofLargeDamsNo.ofLargeDams 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 200 150 100 50 0 15 10 5 0 Number of dams constructed by year. Source: Global Reservoir and Dam (GRanD) Database – Badin Gibbes. 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year of completion Storage capacity of large dams (1900-2010) Global Dams Australian Dams Waterstoragecapacity(millionsofm3) 1,000,000 10,000 100 1 Capacity of dams constructed by year (note logarithmic scale on the y-axis). Divide megalitre units by 1,000 to compare with the units used here. Source: Global Reservoir and Dam (GRanD) Database – Badin Gibbes.
Water Journal November 2014
Water Journal February 2015