Water resources - Allocation and Use - Tasmania
Tasmania
How has Tasmania's water use changed since 1985?
Comparison between the 1985 and 2000 'snapshot' assessments is difficult. Factors include the time between assessments (more than 15 years); seasonality and variability of climate; significant potential for changes in land use; and fluctuations in domestic and global market demands.
Water Use, Climate and the Audit Baseline Year - 1996/97
The baseline year for the Audit is the 1996/97 agricultural year starting on the 1st April and ending on 31st of March. For water use the data was compiled for the period 1 July 1996 to 30 June 1997 (water calendar year). When it is necessary to collect information for more than one year, the data collected must cover that year or, alternatively, appropriately adjusted to provide a best estimate for that year.
For water use data States and Territories were requested to provide a 5 yearly average value based on the 1996/97 year. Use figures were adjusted in areas where, due to climatic conditions, the water use was not considered to be 'average'.
Climate in 1996/97
During 1996 there was a transition from the weak large-scale climate controls to a strong El Ni?o condition after March 1997. This resulted in a drying over a large part of southern and eastern Australia. From July until September 1996 Victoria had unusually cold and wet weather. The remainder of the southern half of Australia was also wet for three months. Significant areas in south-west Queensland, western and central New South Wales, South Australia, western Victoria, and southern Western Australia had rainfall totals within the highest 10% on record.
During the summer of 1996-97, there was a very active monsoonal season in the tropical zones in western Australia and the Northern Territory. However, this finished abruptly and early, as El Ni?o developed rapidly in autumn 1997. From October 1996 very dry conditions prevailed over most of Victoria, the grain belts of South Australia and north-east Tasmania. Areas of southern Victoria through to south-east South Australia had the driest October to June period on record.
May 1997 brought rain to southern Australia and average to above average rain to parts of Queensland. There was some relief to farmers from the dry and hot conditions over southern Australia in early 1997. In parts of southern Victoria and south-east South Australia the driest October to June period was reported. (ABS Water Account, 2000)
Climate in 1983/84 (Water Review 85)
Water use in any particular year is affected by weather conditions. For much of Australia, the period, July 1983 to June 1984, was equivalent to a normal year in which water use was about average. In south-east Australia, however, abnormal weather patterns were experienced. In general, rainfall totals throughout Victoria were high during the first half of the year but were lower than average in the second half. These weather conditions, along with a continuing sensitivity to water use following the 1982/83 drought, had a marked effect on water usage. Although the 1982/83 drought that affected most of Victoria was broken by above-average rains early in the year, water restrictions in many urban areas were not lifted until much later in the year. Urban water use was therefore less than average, due both to the heavy rains and to the continuance of water restrictions.
The above-average rains in the first half of 1983-84 greatly reduced irrigation demands, and by mid-season virtually unrestricted supplies of water were made available to farmers (for example, 200% of water rights in the Goulburn-Murray Irrigation District). The drier conditions in the latter half of the year somewhat compensated for this, but total usage for the year was generally far less than average.
Rural usage was also less than average, again due to the early wet conditions and sensitivity about excessive water use following the 1982-83 drought. (DPIE, 1987).
Note: The change in water use volume from 1985 to 1996 does not always reflect factors affecting consumption patterns and volumes such as population growth, industry or land-use change or operational improvements. The observed difference may partly be attributed to differences in the approach and assumptions used to estimate water use within the river basin.
| Basin Name | Use in 1983-84 (GL /yr) | Use in 1996-97 (GL /yr) | % Change |
|---|---|---|---|
| TAS | 199 | 451 | 126 |
| Arthur River | 0 | 22 | no data |
| Coal River | 1 | 4 | 325 |
| Derwent River | 20 | 75 | 280 |
| East Coast | 4 | 15 | 320 |
| Flinders - Cape Barren Islands | 1 | 1 | 52 |
| Forth River | 3 | 15 | 401 |
| Gordon River | 1 | 0 | -100 |
| Huon River | 3 | 4 | 34 |
| King Island | 1 | 1 | -69 |
| King-Henty Rivers | 1 | 5 | 524 |
| Kingston Coast | 2 | 7 | 420 |
| Mersey River | 18 | 20 | 9 |
| Pieman River | 2 | 9 | 442 |
| Piper-Ringarooma Rivers | 8 | 53 | 557 |
| Rubicon River | 6 | 10 | 85 |
| Sandy Cape Coast | 0 | 0 | no data |
| Smithton-Burnie Coast | 39 | 90 | 133 |
| South-West Coast | 1 | 1 | -21 |
| Tamar River | 25 | 92 | 272 |
Note: The total surface water use reported for each river basin does not include the water consumption of the eleven major cities. The data for cities and river basins are reported in the State totals.
How are the surface water resources used and allocated in Tasmania?
Table: Surface water diversion and allocation 1996-97
| Basin/SWMA Name | Allocation (GL/yr) | Diversion (GL/yr) | Diversion: Allocation (%) |
|---|---|---|---|
| Tasmania | 412 | 3,411 | 1 |
| Arthur River | 22 | 22 | 100 |
| Coal River | 5 | 4 | 70 |
| Derwent River | 778 | 751 | 97 |
| East Coast | 14 | 15 | 104 |
| Flinders - Cape Barren Islands | 1 | 1 | 100 |
| Forth River | 5 | 15 | 293 |
| Huon River | 1,384 | 1,384 | 100 |
| King Island | 1 | 1 | 114 |
| King-Henty Rivers | 205 | 205 | 100 |
| Kingston Coast | 7 | 7 | 100 |
| Mersey River | 752 | 760 | 101 |
| Pieman River | no data | 9 | no data |
| Piper-Ringarooma Rivers | 55 | 53 | 97 |
| Rubicon River | 9 | 10 | 115 |
| Smithton-Burnie Coast | 76 | 90 | 119 |
| South-West Coast | 1 | 1 | 109 |
| Tamar River | 61 | 92 | 152 |
Note: Allocation is not based on 1999-2000 estimates; Diversion based on five-yearly average 1996-97.
Note: In the table above, the total surface water use reported for each river basin does not include the water consumption of the eleven major cities. The data for cities are reported in the State totals. The volume diverted is the total volume of the SWMA's surface water resources diverted for use both within the management area and for export to other management area. The figures include the diversion and allocation for hyrdo-electricity generation in the Tamar River Basin, the Gordon River Basin, the Pieman River Basin, and the Forth River Basin.
The total volume of surface water allocated for use in Tasmania for 1996/97 is 289 GL. This allocation volume refers to rights issued as Commissional Water Rights under the Water Act 1957. Unfortunately this amount could not be accurately broken down into individual use categories for SWMAs for the snapshot year, as information was not available to that level of detail.
The State does have a much finer breakdown of water allocations for the current year and this was used to develop a relationship between 1999/2000 and 1996/97 to provide an estimate of water allocations based on category for SWMAs in 1996/97.
In 1996/97, a number of legal rights to water were not defined volumetrically and could not be included in the Audit as allocations. These included rights for most town water supplies, some fish farms and some irrigation. With the enactment of new water legislation in the State, a conversion process is being put in place to define these allocations.
For 1996/97, in excess of 700 GL of surface water was estimated to be used in Tasmania annually. This use represents both consumptive users and non-consumptive users (fish farming and small hydropower schemes). The total use represents about 4% of the sustainable yield of the resource. After allowing for non-consumptive fish farms this percentage is reduced by about half.
Water use in Tasmania for other than Hydro Electric Corporation power generation is dominated by irrigation and fish farming. As mentioned previously, fish farming is a largely a non-consumptive user of water. Of the consumptive users of water, irrigation is the largest and uses about 67%, or about 265 GL of total based on the 1996/97 usage estimates. Urban and industrial use accounts for a further 24 %, or 94 GL of total use and rural supplies for 9%, or about 36 GL.
Please note: The tables set out below detailing Level 1 and Level 2 water use categories. The sum of the Level 2 water use volumes will not necessarily equal the total Level 1 water use volumes. This is primarily due to lack of more detailed water use data. However, where Level 2 use = Level 1 use then blank cells in the table does not indicate water use unaccounted for in these categories.
Table: Surface water use in Tasmania 1996-97
| Basin/SWMA Name | Irrigation (GL/yr) | Rural (GL/yr) | Urban / Industrial (GL/yr) | Total (GL/yr) | In-situ (GL/yr) |
|---|---|---|---|---|---|
| Tasmania | 267 | 6 | 179 | 451 | 3,248 |
| Arthur River | 2 | no data | 21 | 22 | no data |
| Coal River | 4 | 1 | no data | 4 | 1 |
| Derwent River | 53 | 1 | 23 | 75 | 85 |
| East Coast | 14 | 1 | 1 | 15 | no data |
| Flinders - Cape Barren Islands | 1 | no data | no data | 1 | no data |
| Forth River | 4 | 1 | 11 | 15 | no data |
| Huon River | 2 | 1 | 2 | 4 | 8 |
| King Island | 1 | no data | 1 | 1 | no data |
| King-Henty Rivers | no data | no data | 5 | 5 | no data |
| Kingston Coast | 7 | 1 | no data | 7 | no data |
| Mersey River | 11 | 1 | 10 | 20 | 1 |
| Pieman River | no data | no data | 9 | 9 | no data |
| Piper-Ringarooma Rivers | 23 | 1 | 31 | 53 | 10 |
| Rubicon River | 10 | 0 | no data | 10 | no data |
| Smithton-Burnie Coast | 69 | 1 | 21 | 90 | no data |
| South-West Coast | 1 | no data | no data | 1 | no data |
| Tamar River | 73 | 6 | 14 | 92 | 186 |
How are Tasmania's groundwater resources used and allocated?
In total, 20.2 GL of groundwater is estimated to be used within Tasmania each year. This represents 6.5% of the groundwater within GMUs and less than 1% of the total resource. Mine dewatering (7 GL) and irrigation (9.3 GL) comprise the largest uses of groundwater. Urban water supplies make up only a small component of the current groundwater use.
"GMU"=Groundwater Management Unit "UA"=Unallocated Area
| Province | Use in 1983-84 (GL /yr) | Use in 1996-97 (GL /yr) | % change | Current Alloc (GL/yr) | Current Use : Alloc (%) | GMU / UA |
|---|---|---|---|---|---|---|
| Tasmania | 6 | 21 | 238 | no data | no data | GMU |
| no data | no data | UA | ||||
| Tasmania 1 | no data | 5 | 3 | 3 | 100 | GMU |
| 2 | 0 | UA | ||||
| Tasmania 2 | no data | 15 | 5 | 5 | 101 | GMU |
| 11 | 0 | UA | ||||
| Tasmania 3 | no data | 1 | 1 | 1 | 100 | GMU |
| 1 | 0 | UA |
Table: Groundwater use in Tasmania 1996-97
| Province | Irrigation (GL/yr) | Rural (GL/yr) | Urban / industry (GL/yr) | In-situ (GL/yr) | Total (GL/yr) | SY (GL/yr) |
|---|---|---|---|---|---|---|
| Tasmania | 10 | 4 | 8 | no data | 21 | 2,531 |
| Tasmania 1 | 3 | 2 | 2 | 5 | 1,511 | |
| Tasmania 2 | 7 | 3 | 6 | 15 | 766 | |
| Tasmania 3 | 1 | 1 | 1 | 1 | 256 |
Surface and groundwater interactions
There are no formal licensing arrangements linking groundwater and surface water, with each being registered separately. However on-farm conjunctive use of groundwater and surface water is quite common for irrigation purposes.
Further information
- Tasmania Water Resources Assessment 2000 Report
- Tasmania Water Resources Assessment 2000 Technical Report
- Link to data available for download on the:
- Link to the Map Maker to make a map using this information.
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