Perth

Groundwater discharge to the atmosphere from the saturated zone of each aquifer for the two model regions during 2009-10 are given below.

Data source

Western Australian Department of Water: PRAMS Version 3.4 and PHRAMS groundwater models.

Data provider

Western Australian Department of Water.

Method

Groundwater discharge to the atmosphere was estimated for the Perth region (the area between Gingin and Mandurah) and the Peel-Harvey region (the area south of Mandurah) using the PRAMS and PHRAMS models, respectively. Both models calculate evapotranspiration, which is considered to be equal to the groundwater discharge to ‘landscape’, from the saturated zone of the aquifers. Note that this should not be confused with evapotranspiration from the unsaturated zone, which is rainfall water that has entered the ground in the unsaturated zone but is removed before it reaches the water table at the top of the saturated zone.

Both models use the MODFLOW evaporation module to calculate evapotranspiration from the saturated zone open water wetland surfaces and near surface water table areas.

Uncertainty

Ungraded.

Approximations, assumptions, caveats/limitations

Both models were initially developed to estimate and assess the impacts of changes in climatic conditions and varying extraction rates on the aquifers, not to prepare water accounts. These models have since been modified to also provide data for water accounting.