9.1 Precipitation on surface water
The volumetric value for the line item at the end of the 2011–12 year was 1,648,950 ML.
The line item represents precipitation volumes on surface water assets within the Murray–Darling Basin (MDB) region. Precipitation on storages (included in line item 1.1); regulated river channels, locks and weirs (included in line item 1.3); lakes (included in line item 1.4); and other known water bodies within the region were taken into account in the line item. Information on precipitation on other surface water assets (mainly unregulated rivers and unknown water bodies) is not available.
Precipitation volumes on surface water assets on a surface water resources plan (WRP) area basis is summarised in the following table. Specific details of precipitation on individual asset basis are included in the table thereafter. In the tables, volumes shown against a WRP or surface water sustainable diversion limit (SDL) area are based on surface water assets geographically located within that area.
|Surface water resource plan area||State/Territory||Volume (ML)|
|SW16||Qld Border Rivers||Qld||22,184|
|SW15||NSW Border Rivers||NSW||8,189|
|SW12||NSW Intersecting Streams||NSW||–|
|Sub-total Northern Basin||247,093|
|SW7||NSW Murray and Lower Darling||NSW||347,907|
|SW6||Eastern Mount Lofty Ranges||SA||–|
|Sub-total Southern Basin||1,401,857|
|Total for the region||1,648,950|
– = Data not available
|Water resource plan area||
Sustainable diversion limit area
Surface water asset
Volume (ML) for the 2011–12 year
|SW18 Condamine–Balonne||SS26||Condamine–Balonne||Qld||Buckinbah Weir1||1,735|
|Cooby Creek Reservoir2||2,337|
|Jack Taylor Weir1||2,462|
|Neil Turner Weir2||114|
|SW16 Qld Border Rivers||SS24||Qld Border Rivers||Qld||Glenlyon Lake1||11,819|
|Storm King Reservoir2||916|
|SW15 NSW Border Rivers||SS23||NSW Border Rivers||NSW||Lake Inverell2||330|
|Tenterfield Creek Reservoir 2||224|
|SW14 Gwydir||SS22||Gwydir||NSW||Lake Copeton1||37,319|
|SW13 Namoi||SS21||Namoi||NSW||Chaffey Reservoir1||4,738|
|Split Rock Reservoir1||12,164|
|SW10 Macquarie–Castlereagh||SS20||Macquarie–Castlereagh||NSW||Chifley Reservoir2||2,596|
|Spring Creek Reservoir2||881|
|Suma Park Reservoir2||1,614|
|SW9 Lachlan||SS16||Lachlan||NSW||Carcoar Lake1||3,558|
|SW8 Murrumbidgee NSW||SS15||Murrumbidgee NSW||NSW||Berembed Weir1||735|
|SW7 NSW Murray and Lower Darling||SS18||Lower Darling||NSW||Lake Cawndilla1||28,353|
|Stephens Creek Reservoir2||2,938|
|SS14||NSW Murray||NSW||Lake Hume1||182,328|
|Upstream of Lock 7 (Rufus)2||1,176|
|Upstream of Lock 8 (Wangumma)2||1,576|
|Upstream of Lock 9 (Kulnine)2||2,676|
|Upstream of Lock 10 (Wentworth)2||2,749|
|Upstream of Lock 15 (Euston)2||22,106|
|SW2 Vic. Murray||SS3||Kiewa||Vic.||Lake Guy2||190|
|Rocky Valley Storage2||5,693|
|SW3 Northern Victoria||SS4||Ovens||Vic.||Lake Buffalo1||2,783|
|Lake William Hovell1||1,520|
|McCall Say Reservoir1||138|
|SS6||Goulburn||Vic.||Goulburn Weir 1||7,368|
|Upper Coliban Reservoir2||2,559|
|SS8||Loddon||Vic.||Barkers Creek Reservoir2||462|
|Cairn Curran Reservoir1||9,629|
|Laanecoorie Reservoir 1||2,146|
|Newlyn Reservoir 1||500|
|Spring Gully Reservoir2||254|
|SW2 Vic. Murray||SS2||Vic. Murray||Vic.||Kangaroo/Racecourse Lake2||4,048|
|Upstream of Lake Mulwala2||21,179|
|Upstream of Mildura Weir2||9,782|
|SW4 Wimmera–Mallee||SS9||Wimmera–Mallee||Vic.||Dock Lake1||2,213|
|Lake Batyo Catyo1||549|
|SW5 SA Murray||SS11||SA Murray||SA||Blanchetown Weir – Lock 11||4,041|
|Bookpurnong Weir – Lock 41||2,265|
|Overland Weir – Lock 31||3,786|
|Renmark Weir – Lock 51||2,844|
|Upstream of Lock 6 (Murtho)2||3,752|
|Upstream of Lake Alexandrina2||16,331|
|Waikerie Weir – Lock 21||3,208|
|SW1 ACT||SS1||ACT||ACT||Bendora Reservoir1||1,085|
|Lake Burley Griffin 2||5,525|
|Total for the region||
- Dynamic surface area used
- Static surface area used (based on boundaries defined for surface water bodies in Bureau of Meteorology's [the Bureau's] Australian hydrological geospatial fabric [AHGF]).
Monthly precipitation data was produced by the Bureau. It was 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).
The precipitation at each waterbody was estimated from the proportionally weighted average of grid points that intersected each water feature. The volume was then estimated using the surface area of each waterbody. The surface area varied dynamically with changing level for storages, lakes and weirs where the relationship between storage level and surface area had been derived; where this relationship was not available the static AHGF surface area was used.In the MDB region, precipitation on the surface water store included the precipitation falling on the water bodies mentioned in the supporting information.
Assumptions, limitations, caveats and approximations
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 lakes at capacity and therefore likely results in an overestimation of precipitation on the lake.
The following changes resulted in the restatement of the 2010–11 year volume:
- error correction
- scope change.
The changes and their respective values are detailed in the table below.
2012 Account volume for the 2010–11 year (ML)
2011 Account volume for the 2010–11 year (ML)
Difference due to prior period error correction and scope change (ML)
Scope change was due to inclusion of McCall Say Reservoir, Lake Batyo Catyo, Pine Lake, Dock Lake and Green Lake (not included in the 2011 Account) in the 2012 Account. Resulting volume increase due to the scope change for the 2010–11 year is not available.
Prior period error correction was due to a calculation error made in the volumes reported in the 2011 Account. Resulting volume increase for all surface water assets due to the prior period error correction for the 2010–11 year was 106,105 ML, which represents a change of 5% of the previously reported value.