Perth
10.1 Groundwater inflow from outside region

Supporting information

a. Supporting Information

The volume reported in the water accounting statements (48,940 ML) represents the total volume of groundwater inflow from outside the Perth region boundary into aquifers within the Perth region during the 2012–13 year.

Lateral inflows into each groundwater store within the two model areas during the 2012–13 year are given in the following table.

 

Volume of groundwater inflow from outside the Perth region during the 2012–13 year

 

Inflow (ML)

Groundwater store

Perth area

Peel–Harvey area

water table aquifer

19,912

1,006

underlying aquifer—Leederville

11,164

1,452

underlying aquifer—Yarragadee

15,406

0

Total

48,940

 

b. Groundwater models

The Department of Water use the Perth Regional Aquifer Modelling System (PRAMS) version 3.4 and Peel–Harvey Regional Aquifer Modelling System (PHRAMS) to estimate the natural water movement to and from the groundwater store within the Perth region.

As shown in the following figure, PRAMS estimates groundwater movement for the area north of Mandurah. PHRAMS estimates groundwater movement for the Peel–Harvey area south of Mandurah. The volumes reported in this account refer to the natural water movement that occurs within each model area within the Perth region boundary.


Map of groundwater model areas relative to the Perth region boundary
Map of groundwater model areas relative to the Perth region boundary

Quantification approach

Data source

PRAMS version 3.4 and PHRAMS groundwater models.

Provided by

Department of Water.

Method

Both groundwater models derive the lateral flux within the Perth region by defining the appropriate water balance zones and calculating the volume of water flowing across each boundary on an annual basis.

Assumptions, limitations, caveats and approximations

It is assumed that all groundwater flow to and from outside the region is via the north and south boundaries. There is no groundwater flow between the model areas and the Darling Range in the eastern part of the region due to the geology of that area.

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

Uncertainty information

The uncertainty estimate was not quantified.