Perth

This line item refers to total precipitation on the major reservoirs within the Perth region.

Total volume of rainfall on each reservoir during 2009-10 within the Perth region is provided in the table below.

Data source

Bureau of Meteorology: monthly precipitation grids, Australian Hydrological Geospatial Fabric waterbody feature class andwater storages.

Data provider

Bureau of Meteorology.

Method

Monthly precipitation data were produced by the Bureau. These data werebased on daily data from approximately 6500 rain gauge stations and interpolated to a 0.05 degree (5 km) national grid (Jones et al. 2007).

The precipitation at each waterbody was estimated from the average of the grid points within a 5 km radius of 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.

Uncertainty

Ungraded.

Approximations, assumptions, caveats/limitations, assumptions, caveats/limitations

• 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 reservoirs (and not the river channels).