Efficient water storage and delivery
Water is lost to productive use throughout the water delivery and storage system. Dams lose water to evaporation and seepage; water use is poorly monitored resulting in overuse; and irrigation channels leak and overflow. The scale of the problem is very large and the cost to remedy the situation is also large. For example, Pratt Water (2004) estimate that it would cost $3 billion to pipe the irrigation channels in the Murrumbidgee Irrigation Area to provide a saving of 151 GL/yr. Such a scheme is not economical, but there are other ways to manage the water supply so as to save water without such a high capital cost. In the above example, Pratt (2004) also noted that sealing the worst sections of irrigation channel would cost about $150 million and save 91GL/year. Even making more accurate measurements of existing water use is part of the process. In the Murray Darling Basin, the total diversion is only accurate to 7% of volume, which amounts to 557 GL in 2002/03 (MDBC, 2004).
The amount of water lost to evaporation and leakage from surface water storages is not known, although evaporation from large dams alone is in excess of 2,000 GL/year (Table 1). Farm dams are thought to contribute about 1,500 GL/yr through evaporation and seepage (Marohasy, 2003). Making water storage more efficient throughout Australia through water banking could reduce these evaporative losses. Using local aquifers to store water in irrigation areas and urban areas can overcome some of the inefficiencies inherent in delivering water from distant dams. It is more common for suitable aquifers rather than dam sites to be co-located in areas of water demand.
| Dam name | Potential water evaporated (GL/yr) |
|---|---|
| Lake Victoria, NSW | 1730 |
| Lake Argyle, WA | 1400 |
| Menindee Lakes, NSW | 850 |
| Burdekin Falls Dam, QLD | 300 |
| Fairbairn Dam, QLD | 220 |
| Hume Dam, VIC | 200 |
| Lake Gordon, TAS | 140 |
| Lake Eildon, VIC | 100 |
| Warragamba Dam, NSW | 80 |
References
Marohasy J, 2003. Myth and the Murray: measuring the real state of the river environment. IPA Backgrounder, December 2003, Volume 15/5,
Pratt Water, 2004. The business of saving water, the report of the Murrumbidgee Valley water efficiency feasibility project. Commonwealth of Australia, 152 pp.
Trewin D, 2005. Wateruse on Australian Farms 2002-03. Australian Bureau of Statistics, ABS Catalogue 4618.0, 54 pp.
MDBC, 2004. Water Audit Monitoring Report 2002/03