The Perth region
Overview of the 2012–13 year
The Perth region is home to waterways and wetlands of national significance. The region also contains important groundwater resources that support numerous groundwater-dependent wetland ecosystems. In the last 30 years, the region has experienced a decline in rainfall that has resulted in a reduction in storage refill and aquifer recharge.
Rainfall across the entire Perth region was below average for the 2012–13 year. These rainfall conditions, compared to the 2011–12 year, contributed to decreased inflows into the storages and a reduction in aquifer recharge. Closing net water assets in the Perth region was 47,997 ML, slightly lower than the previous year of 54,906 ML. For more information on the region's water assets refer to Water accounting statements.
During the 2012–13 year the first stage of the Southern Seawater Desalination Plant was able to operate at the plant's capacity for the entire year. This increased the supply of desalinated water to the urban water system by more than 20% from the previous year. Desalinated water made up almost 30% of the urban supply water during the 2012–13 year. Consequently, there was slightly less dependence on groundwater for urban supply compared to the previous year.
The key water account information for the Perth region during the 2012–13 year is presented in the following table. Information on the uncertainty associated with the volumes presented in the table is provided in the relevant sections of the account.
Key water account information for the Perth region during the 2012–13 year
|Rainfall: 586 mm||Rainfall: 805 mm||Rainfall: 780 mm|
|Evapotranspiration: 643 mm||Evapotranspiration: 689 mm||Evapotranspiration: 632 mm|
|For more detail on the Perth climate refer to Climate overview.|
|Swan-Canning River||Murray River||Harvey River|
|well below mean annual flow||below mean annual flow||below mean annual flow|
|For more detail on streamflow in the Perth region refer to Water overview.|
|Total water assets (as at 30 June)||190,564||217,185|
|Total water liabilities (as at 30 June)||142,567||162,279|
|Change in net water assets||(6,909)||75,536|
|Closing net water assets||47,997||54,906|
|For more detail on water assets and water liabilities refer to Water accounting statements.|
Notes: Water resources and systems
|30 June 2013||30 June 2012|
|Total capacity||Volume||% of capacity||Volume||% of capacity|
|698,300 ML||183,415 ML||26.3%||209,455 ML||30.0%|
|For more detail on surface water storage in the Perth region refer to Surface water.|
|Total water abstracted|
|Surface water: 169,742 ML||Surface water: 155,347 ML||Water abstraction for urban water supply has decreased.|
|Groundwater: 486,741 ML||Groundwater: 514,995 ML|
|For more detail on water abstraction in the Perth region refer to Surface water and Groundwater.|
|Total water supplied|
|327,184 ML||318,189 ML||Increased dependence on desalinated water supply.|
|For more detail on the urban water system in the Perth region refer to Urban water system.|
|Total water supplied|
|21,910 ML||24,133 ML||Diversion of surface water to the scheme has decreased.|
|For more detail on the irrigation scheme in the Perth region refer to Irrigation scheme.|