4610.0.55.007 - Water and the Murray-Darling Basin - A Statistical Profile, 2000-01 to 2005-06
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 15/08/2008 First Issue
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AGRICULTURAL WATER CONSUMPTION
Water Sources The source of water used for agricultural production is of interest to policy makers and water resource managers (see Appendix). Issues that are of particular interest include:
Surface and groundwater sources In 2005–06, the majority of water consumption by the Agriculture industry in the MDB originated from two main sources: surface water (6,499 GL) and groundwater (1,069 GL) (table 3.11). Combined, these two sources accounted for 98% of all water consumed for agricultural production in the Basin: 84% surface water, 14% groundwater. Other sources accounting for the remaining 2% of water consumption included recycled or reused water from off-farm sources and reticulated mains supply. Although 14% of all agricultural water consumption inside the MDB was sourced from groundwater, areas outside the MDB were more reliant on groundwater, with 33% of water consumption originating from this source. As shown in table 1.9, the long-term average annual run-off (23,609 GL) and deep drainage (9,719 GL) produce the long-term average water availability in the MDB of 33,328 GL. In 2005-06, agricultural water consumption was 7,720 GL (table 3.11), or 23% of the long-term average water availability in the MDB. Nation-wide, agricultural water consumption (11,689 GL) represents 3% of Australia's long-term average water availability (413,264 GL). As a proportion of long-term average annual run-off in the MDB (table 1.9), surface water consumption by Agriculture represented 28% in 2005–06. In contrast, groundwater consumption (1,069 GL) represented 11% of the long-term average annual deep drainage.
Location of surface and groundwater use In 2005-06, the majority of surface water consumption by the Agriculture industry in the MDB was in New South Wales (57%) and Victoria (30%). Over 70% of the 1,069 GL of groundwater consumption in the MDB occurred in New South Wales (table 3.12). A relatively low volume of groundwater (151 GL or 14%) was extracted for consumption by the Agriculture industry in the Victoria section of the Basin.
River basin scale measurement of water use from surface and groundwater sources is important for water management and planning agencies, because water management plans and water resource assessments commonly report at this level. Of the approximately 6,500 GL sourced from surface water in the MDB in 2005-06, most was from the Murrumbidgee (1,446 GL), Murray-Riverina (850 GL), Loddon (643 GL) and Goulburn (417 GL) river basins (table 3.14). These are also the basins with the highest total agricultural water consumption. Map 3.13 illustrates the volumes of surface water used for agricultural production in MDB Statistical Local Areas (SLAs, see map E.2 in the Explanatory Notes) in 2005-06. The data was sourced from the ABS Agricultural Census. This level of geography has been used to provide a more detailed picture of the distribution of surface water consumption relative to river basins in the MDB. The pattern demonstrates that in 2005-06, surface water was consumed in most Basin SLAs, and that the highest quantities of water consumption were in SLAs in the southern and northern MDB. 3.13 Agricultural surface water consumption in river basins, by Statistical Local Area—Murray-Darling Basin—2005-06 In 2005–06, groundwater accounted for 14% (or 1,069 GL) of agricultural water consumption in the MDB. Most of the water sourced from groundwater in the Basin occurred in the Murrumbidgee (218 GL), Namoi (185 GL) and Lachlan (144 GL) river basins (table 3.14). Groundwater was a more important water source to farmers in the Namoi and Lachlan river basins than other river basins, contributing 41% and 38% of total water consumption respectively). Within these river basins, groundwater consumption was spread across the Namoi river basin SLAs, while for the Murrumbidgee and Lachlan river basins, most groundwater consumption occurred in the SLAs located in the lower regions (see map 3.15 sourced from the Agricultural Census).
3.15 Agricultural groundwater consumption in river basins, by Statistical Local Area—Murray-Darling Basin—2005–06 Change in water sources Comparable agricultural surface and groundwater consumption data are not available for the MDB before 2005–06. However, as table 3.16 shows, of the total state surface and groundwater consumption, the MDB section of New South Wales accounts for 94% of both sources. Therefore, assessing the change in surface and groundwater consumption in New South Wales between 2004-05 and 2005-06 would be indicative of the change in the New South Wales section of the MDB. In other states (Victoria, Queensland and South Australia), the proportion of surface and groundwater consumption in the MDB as a proportion of the total state, are lower. Therefore, assessing the change in surface and groundwater consumption in those states is less indicative of the change in the MDB section of each respective state.
The change in surface and groundwater consumption in New South Wales from 2004-05 to 2005-06 is shown in table 3.17. The volume of groundwater extracted by farmers decreased from almost 950 GL (25% of total water consumption) in 2004-05 to 810 GL (or 17%) in 2005-06. The decrease in groundwater used as a water source coincides with an increase in surface water consumption; from almost 2,800 GL (73% of total water consumption) to over 3,920 GL (or 82%). One hypothesis for this trend is when more water is available for use from surface water storages (e.g. as in 2005-06, see graph 3.18) farmers use less groundwater for agricultural purposes. Conversely, when less surface water is available as a result of lower allocations induced by reduced water storage (e.g. in 2004-05), more groundwater is used. Although the data to support this hypothesis are limited, it would be expected that for 2006-07, when surface water storages were very low in the MDB, there may be some increase in the use of groundwater by farmers. Data which would enable this comparison are expected to be available in Water Use on Australian farms, 2006-07 (cat. no. 4618.0) in the near future.
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