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National Water Account 2016

Murray–Darling Basin: Statement details

Despite several heavy rainfall events that occurred during the year, relatively poor rainfall over most of the year contributed to low annual streamflows and storage inflows across the region. Storage volumes dropped from 42% to 39% full during the 2015–16 year, the fourth successive annual decrease since 2012.

 

 

 

Water assets

Surface water assets

Surface water asset volumes in the Murray–Darling Basin region at 30 June 2016 (13,521,272 ML) comprised of water held in:

  • storages—9,059,525 ML
  • rivers—1,960,497 ML
  • lakes and wetlands—1,875,002 ML
  • other assets—18,105 ML
  • claims: inter-region—608,143 ML.

The location of each storage within the region and the volume of water in each storage (including dead storage) as a percentage of total storage capacity at the end of the year is shown in Figure S1.

 

Figure S1 Percentage-full volume on 30 June 2016 for major storages within the Murray–Darling Basin region
Figure S1 Percentage-full volume on 30 June 2016 for major storages within the Murray–Darling Basin region

 

The total volume of water in the region's storages decreased during the 2015–16 year from 42% to 39% full at 30 June 2016 (Figure S2), which can be attributed to the below average rainfall for the majority of the year (see Climate and water). This was the fourth successive drop in annual storage volume in the region.

Information on the individual storages within the region is given on the Bureau of Meteorology's Water Storage website.

 

Figure S2  Graph of total storage volume in the region at 30 June 2016 compared with the previous 6 years
Figure S2 Total storage volume in the region at 30 June 2016 compared with the previous six years
 

 

The total volume of water in the region's lakes and wetlands and other assets at 30 June 2016 was similar to that at the start of the 2015–16 year. The volume of water in rivers increased from last year, primarily due to high rainfall events that occurred near the end of the reporting period (May–June 2016).

The inter-region claim is the balance remaining on the required annual release from Snowy Hydro Limited to the Tumut and Murray rivers at the end of the 2015–16 year (Table S1). The required annual release (increase of claim), the delivery of the water, and the forfeiture (decrease of claim) for the inter-region agreement is also provided in Table S1.

 

Table S1 Volume of surface water inter-region claims remaining at the end of the 2015–16 year
 Volume
ML
Opening balance at 1 July 20151,238,860
Increase of claims1,761,592
Delivery: inter-region agreement(2,392,309)
Decrease of claims(0)
Closing balance at 30 June 2016608,143

 

More detailed information on the inter-region claim from Snowy Hydro Limited is provided in this downloadable table.

 

Groundwater assets

The groundwater asset volume in the Murray–Darling Basin region at 30 June 2016 was 3,333,740 ML. Sustainable diversion limit volumes provided by the Murray–Darling Basin Authority were recognised as groundwater assets. Sustainable diversion limits represent the long-term average of groundwater available for use, not the actual volume of water available in the aquifers on any particular date.

 

Water liabilities

Water liabilities in the Murray–Darling Basin region refer to the volume of allocation remaining on licence entitlements at the end of the 2015–16 year.

Water supply licences for individual users and environmental purposes have carryover provisions, which means a portion of the unused component of the annual allocation can be carried over to the following year. This is equal to the allocation remaining at the end of the 2015–16 year (tables S2–S3). There are no carryover provisions for urban water entitlements, so the portion of the annual allocation that has not been taken by the end of the year is forfeited.

The allocation (water liability increases), allocated abstraction (water outflow), and the adjustment and forfeiture (water liability decreases) for each licence entitlement is also provided in tables S2–S3.

A more detailed description of all water allocations and associated water rights in the Murray–Darling Basin region is provided in the Water access and use note.

 

Table S2 Volume of surface water allocation remaining at 30 June 2016
 Individual users
(ML)
Urban system
(ML)
Environmental purposes
(ML)
Opening balance at 1 July 20151,977,0020877,283
Allocation4,488,836542,6591,386,979
Allocated diversion(5,177,950)(466,198)(1,912,884)
Adjustment and forfeiture549,952(76,491)507,339
Closing balance at 30 June 20161,837,840(30)858,717

 

Table S3 Volume of groundwater allocation remaining at 30 June 2016
 Individual users
(ML)
Urban system
(ML)
Environmental purposes
(ML)
Opening balance at 1 July 2015749,86002,256
Allocation2,166,33350,6811,273
Allocated extraction(1,270,177)(21,147)(0)
Adjustment and forfeiture(990,726)(29,534)(688)
Closing balance at 30 June 2016655,29002,841

 

Water asset increases

Total water asset increases for the region of 23,489,053 ML comprised:

  • surface water increases—23,078,494 ML
  • groundwater increases—410,559 ML.

The key surface water asset increase for the region was runoff, which made up more than 80% of the surface water increases. During the 2015–16 year, runoff was more than 30% greater than the previous year. This increase in runoff is largely attributed to several high rainfall events that occurred during the year (see Climate and water). Despite the increased runoff (which mostly occurred during May and June 2016 and had not completely reached the storages by the end of the year), it was still relatively low when compared to earlier years (see 2011 Account). Consequently, storage volumes dropped during the year, but not as much as the previous three years (see Water assets).

The key groundwater asset increases for the region was recharge: landscape, which made up more than 99% of the groundwater increases. The volume of recharge presented in the statements was much less than the previous year as information for the 2015–16 year was only available for selected aquifers.

 

Water asset decreases

Total water asset decreases for the region of 15,830,937 ML comprised:

  • surface water decreases—15,505,870 ML
  • groundwater decreases—325,067 ML.

The key surface water asset decreases for the region were river and floodplain losses and evaporation, which made up approximately 65% and 25% of the surface water decreases, respectively. During the 2015–16 year, evaporation was approximately 25% less than the previous year, reflecting the increased rainfall compared to last year (see Climate and water). 

The key groundwater asset decrease was extraction: statutory rights, which made up almost 75% of the groundwater decreases. Extractions under statutory rights for the 2015–16 year were marginally higher than last year.

 

Water flows

Total water inflows to the region of 24,119,770 ML differ to the volume of Water asset increases of 23,489,053 ML because the volume of water asset increases includes an inter-region claim on surface water of 1,761,592 ML while the volume of water inflows includes the delivered portion of that inter-region claim of 2,392,309 ML.

Total water outflows from the region of 24,679,293 ML were higher than the volume of Water asset decreases of 15,830,937 ML because the volume of water outflows also includes the flows corresponding to the accrual transactions; that is, the allocated water diversions (see the Water liabilities section above).

A detailed description on all the water inflows and outflows associated with the surface water and groundwater stores is provided in the Water stores note.

 

Unaccounted-for difference

The volume recognised in the water accounting statements 1,013,923 ML represents the total unaccounted-for difference for the Murray–Darling Basin region for the 2015–16 year.

The unaccounted–for difference is the volume necessary to reconcile the opening water storage and closing water storage with the total water inflows and total water outflows reported in the water accounting statements. It is calculated according to Table S4.

 

Table S4 Calculation of unaccounted-for difference for the 2015–16 year
 Volume
(ML)
Opening water storage balance (1 July 2015) 15,792,469
Total water inflows 24,119,770
Total water outflows (24,679,293)
Closing water storage balance (30 June 2016) (16,246,869)
Unaccounted-for difference
 1,013,923

 

The unaccounted–for difference can also be calculated by tallying the volumes necessary to reconcile (balance) the opening and closing storage with the water inflows and outflows of each of the separate water stores of the region, as shown in Table S5.

 

Table S5 Balancing volumes of the water stores of the Murray–Darling Basin region for the 2015–16 year
 Volume
(ML)
surface water store 0
groundwater store 1,013,923
Unaccounted-for difference
 1,013,923

 

The entire unaccounted-for difference volume is explained by the balancing item of the groundwater store (Table S5). The groundwater balancing item is largely attributed to the uncertainty associated with modelling natural groundwater movement, as well as the exclusion of aquifer storage volumes in the account. See the Water stores note for more information.