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


Contextual information: Climate overview
Climate Overview 2012–13 2011–12 Long–term average
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.

 

Contextual information: Water overview
Water 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.

 

Water accounting statements
Accounting statements 2012–13 2011–12
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

 

Surface water storage
Surface water 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.

 

Water abstractions
Groundwater Total water abstracted
2012–13 2011–12 Recent activity
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.

 

Urban water supply
Urban water system Total water supplied  
2012–13 2011–12 Recent activity
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.

 

Irrigation scheme supply
Irrigation scheme Total water supplied  
2012–13 2011–12 Recent activity
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.