Until the outcome of the 2025 federal election, the Australian Government is operating under caretaker conventions

Perth
9.1 Precipitation on surface water

Supporting information

The volume reported in the water accounting statements (20,317 ML) represents the volume of precipitation that fell on the major surface water storages within the Perth region during the 2012–13 year.

The total volume of rainfall on each storage during the 2012–13 year within the Perth region is provided in the following table.

 

Total rainfall on each storage within the Perth region during the 2012–13 year

Storage

Rainfall (ML)

Canning

1,389

Churchman Brook

139

Drakes Brook

317

Harvey

2,986

Logue Brook

528

Mundaring

2,339

North Dandalup

1,615

Samson Brook

237

Serpentine

2,990

Serpentine Pipehead

452

South Dandalup

2,567

Stirling

2,233

Victoria

312

Waroona

575

Wungong

1,638

Total

20,317

 

Quantification approach

Data source

Monthly precipitation grids, Australian Hydrological Geospatial Fabric—waterbody feature class, Australian Water Resources Information System—water storages.

Provided by

Bureau of Meteorology.

Method

Monthly precipitation grids were produced using daily data from approximately 6,500 rain gauge stations and interpolated to a 0.05 degree (5 km) national grid (Jones et al. 2007). 

The precipitation on each waterbody was estimated from the proportionally weighted average of grid-cells that intersected each water feature. The volume was then estimated using the surface area of each waterbody. The average monthly surface area of the major storages was calculated from daily storage levels and capacity tables.

The surface area of all the storages in the Perth region was calculated using this dynamic method.

Assumptions, limitations, caveats and approximations

The precipitation estimates were subject to approximations associated with interpolating the observation point data to a national grid as detailed in Jones et al. (2007).

The dynamic storage surface areas calculated from the levels and capacity tables represent a monthly average and therefore will not capture changes that occur on a shorter temporal scale.

The total surface area of the surface water store within the Perth region included only the storages (and not the rivers).

Uncertainty information

The uncertainty estimate was not quantified.