South East Queensland

Data source

Bureau of Meteorology: monthly precipitation grids, Australian Hydrological Geospatial Fabric (AHGF) waterbody feature class, AHGF stream network feature class, and water storages.

Data provider

Bureau of Meteorology.

Method

Monthly precipitation data grids are produced by the Bureau of Meteorology. These are based on 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 average of the grid-points 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 most of the storages in the South East Queensland (SEQ) region was calculated using this dynamic method. Storage rating table data and regularly updated storage level data were not available for all of the storages, so static surface areas were used. The surface area for Cedar Grove and Mount Crosby weirs was provided by Seqwater. For Lake Cressbrook, Lake Perseverance and Splityard Creek Dam, the AHGF waterbody feature class was used to estimate a static surface area. For the SEQ region, the precipitation on the connected surface water store included precipitation on storages only.

Uncertainty

Ungraded.

Approximations, assumptions, caveats and limitations

• The precipitation estimates were subject to approximations associated with interpolating the observation point data to a national grid.
• 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 use of the static default waterbody feature class surface area is an approximation only. It represents the storage at capacity and therefore probably results in an overestimation of precipitation on the storage. This default data-set was only used for the small storages; therefore, the impact of this approximation is estimated to be small.