Adelaide
9.1 Precipitation on surface water

The volume reported (6,783 ML) represents the total precipitation falling onto surface water storages and weirs in the Adelaide region during the 2012–13 year.

Precipitation, itemised by each surface water storage and weir, is provided in the following table.

Precipiation on storages and weirs in the Adelaide region during the 2012–13 year

Surface water storage	Volume (ML)
Barossa Reservoir1	271
Barossa Weir2	14
Clarendon Weir3	41
Gorge Weir4	14
Gumeracha Weir5	110
Happy Valley Reservoir6	787
Hope Valley Reservoir7	188
Kangaroo Creek Reservoir8	260
Little Para Reservoir9	305
Millbrook Reservoir10	698
Mount Bold Reservoir11	953
Myponga Reservoir12	1,596
Onkaparinga Summit Reservoir13	63
South Para Reservoir14	1,055
Warren Reservoir15	428
Total	6,783

^{6-12, 14-15} Precipitation calculation used dynamic surface area.
^{1-5, 13} Precipitation calculation used static surface area.

National Climate Centre daily climate grids (rainfall), Australian Hydrological Geospatial Fabric (AHGF) waterbody feature class, Australian Water Resources Information System (AWRIS)—Water storages.

Bureau of Meteorology.

Monthly precipitation data were produced by the Bureau of Meteorology. These were based on daily data from approximately 6,500 rain gauge stations and interpolated to a 0.05 degree (approximately 5 km) national grid (Jones et al. 2007).

Precipitation at each waterbody was estimated from the proportionally weighted average of grid-point cells that intersected each storage or weir (water feature). The precipitation volume was then estimated using the surface area of each waterbody. Surface area varied dynamically with changing storage level for storages, where the relationship between storage level and surface area has been derived. The surface area of storages was either calculated dynamically or was a static value produced from the AHGF (refer to previous table). The surface area of all weirs was a static value produced from the AHGF.

 

• The precipitation estimates were subject to approximations associated with interpolating observation point data to a national grid 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 use of the static default AHGF surface area is an approximation only. It represents the water features at capacity and therefore likely results in an overestimation of precipitation on the water features.
• Precipitation was only estimated for the surface water storages and weirs (for which data were available) within the Adelaide region and does not include river channels.

The uncertainty estimate was not quantified.