Murray–Darling Basin
17.1 Evaporation from surface water

Supporting information

The volumetric value for the line item at the end of the 2011–12 year was 3,258,419 ML.

The line item represents evaporation volumes from surface water assets within the Murray–Darling Basin (MDB) region. Evaporation from 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 evaporation from other surface water assets (mainly unregulated rivers and unknown water bodies) is not available.

Evaporation volumes from surface water assets on water resources plan (WRP) area basis are summarised in the following table. Specific details of evaporation from individual asset basis are included in the table thereafter. In the tables, volumes shown against a WRP or sustainable diversion limit (SDL) area are based on surface water assets geographically located within that area.

 

Summary of the evaporation volumes on surface water assets in the MDB region in the 2011–12 year
Surface water resource plan area State/Territory  Volume (ML) 

Code

Name

SW19 Warrego–Paroo–Nebine Qld
SW18 Condamine–Balonne Qld 69,228
SW17 Moonie Qld
SW16 Qld Border Rivers Qld 42,609
SW15 NSW Border Rivers NSW 13,483
SW11 Barwon–Darling Watercourse NSW
SW12 NSW Intersecting Streams NSW
SW14 Gwydir NSW 50,311
SW13 Namoi  NSW 81,339
SW10 Macquarie–Castlereagh NSW 109,285
Sub-total Northern Basin 366,255
SW9 Lachlan  NSW 149,290
SW8 Murrumbidgee NSW NSW 110,242
SW7 NSW Murray and Lower Darling NSW 993,975
SW3 Northern Victoria  Vic. 321,737
SW2 Vic. Murray Vic. 212,034
SW4 Wimmera–Mallee  Vic. 68,804
SW6 Eastern Mount Lofty Ranges SA
SW5 SA Murray SA 1,015,985
SW1 ACT ACT 20,097
Sub-total Southern Basin 2,892,164
Total for the region 3,258,419

 

Specific details of evaporation volumes on individual surface water asset basis in the MDB region in the 2011–12 year
Water resource plan area

Sustainable diversion limit (SDL) area

State/Territory

Surface water asset

 Volume (ML) for the 2011–12 year 

Code

Name

SW18 Condamine–Balonne SS26 Condamine–Balonne Qld Buckinbah Weir1 2,782
Chinchilla Weir1 3,734
Connolly Reservoir2 566
Cooby Creek Reservoir2 3,289
Jack Taylor Weir1 4,043
Lake Kajarabie1  37,982
Lake Leslie1  15,353
Moolabah Weir1 1,328
Neil Turner Weir2 149
SW16 Qld Border Rivers SS24 Qld Border Rivers Qld Glenlyon Lake1 22,307
Lake Coolmunda1  19,088
Storm King Reservoir2 1,213
SW15 NSW Border Rivers SS23 NSW Border Rivers NSW Lake Inverell2  470
Pindari Lake1 12,717
Tenterfield Creek Reservoir2 296
SW14 Gwydir SS22 Gwydir NSW Lake Copeton1  49,262
Tareelaroi Weir1 1,049
SW13 Namoi  SS21 Namoi  NSW Chaffey Reservoir1 6,216
Dungowen Reservoir2 563
Gunidgera Weir1 801
Lake Keepit1  54,174
Mollee Weir1 1,334
Quipolly Reservoir2 1,360
Split Rock Reservoir1 16,893
SW8 Macquarie–Castlereagh SS20 Macquarie–Castlereagh NSW Chifley Reservoir2 3,116
Lake Burrendong1  82,452
Lake Oberon2  4,406
Lake Windamere1  15,001
Rylstone Reservoir2 1,034
Spring Creek Reservoir2 938
Suma Park Reservoir2 1,870
Timor Reservoir2 233
Winburndale Reservoir2 234
Northern Basin

366,255

SW9 Lachlan  SS16 Lachlan  NSW Carcoar Lake1 3,979
Lake Brewster1  70,346
Lake Cargelligo1  16,094
Lake Endeavour2  661
Lake Rowlands2  959
Lake Wyangala1  57,252
SW8 Murrumbidgee NSW SS15 Murrumbidgee NSW NSW Berembed Weir1 1,178
Blowering Reservoir1 42,174
Gogeldrie Weir1 2,314
Hay Weir1 4,486
Lake Burrinjuck1  54,535
Maude Weir1 1,746
Redbank Weir2 212
Tombullen Storage1 3,596
SW7 NSW Murray and Lower Darling SS18 Lower Darling NSW Lake Cawndilla1  146,993
Lake Menindee1  195,231
Lake Victoria1  131,510
Lake Wetherell1  111,536
Pamamaroo Lake1 87,039
Stephens Creek Reservoir2 8,930
SS14 NSW Murray NSW Lake Hume1  198,930
Upstream of Lock 7 (Rufus)2 5,358
Upstream of Lock 8 (Wangumma)2 7,753
Upstream of Lock 9 (Kulnine)2 12,436
Upstream of Lock 10 (Wentworth)2 11,853
Upstream of Lock 15 (Euston)2 76,407
SW2 Vic. Murray SS3 Kiewa Vic. Lake Guy2  82
Rocky Valley Storage2 1,846
SW3 Northern Victoria SS4 Ovens Vic. Lake Buffalo1  1,826
Lake William Hovell1 1,302
SS5 Broken Vic. Lake Nillahcootie1  5,590
McCall Say Reservoir1 114
SS6  Goulburn  Vic. Goulburn Weir 1 12,170
Greens Lake1 8,395
Lake Eildon1  131,599
Waranga Basin1 56,993
SS7 Campaspe Vic. Campaspe Weir2 281
Lake Eppalock1  33,224
Lauriston Reservoir2 2,390
Malmsbury Reservoir2 3,228
Upper Coliban Reservoir2 3,094
SS8 Loddon Vic. Barkers Creek Reservoir2 615
Cairn Curran Reservoir1 19,034
Crusoe Reservoir2 318
Evansford Reservoir2 303
Hepburn Lagoon2 1,047
Kow Swamp2 26,097
Laanecoorie Reservoir 1 4,953
McCay Reservoir2 199
Newlyn Reservoir 1 659
Sandhurst Reservoir2 316
Spring Gully Reservoir2 403
Tullaroop Reservoir1 7,588
SW2 Vic. Murray SS2 Vic. Murray Vic. Kangaroo/Racecourse Lake2 12,767
Lake Banimboola2  571
Lake Dartmouth1  55,425
Lake Mulwala1 47,989
Mildura Weir2  1,449
Reedy/Middle Lake2 4,289
Third Lake2 2,456
Torrumbarry Weir1 9,568
Upstream of Lake Mulwala2 30,518
Upstream of Mildura Weir2 45,072
SW4 Wimmera–Mallee SS9 Wimmera–Mallee  Vic. Dock Lake1  5,950
Green Lake 1,791
Lake Batyo Catyo1 1,523
Lake Bellfield1  4,873
Lake Fyans1  4,888
Lake Lonsdale1  23,205
Lake Taylor1  3,849
Lake Whitton2  828
Pine Lake 3,185
Toolondo Reservoir1 9,119
Wartook Reservoir1 9,591
SW5 SA Murray SS11 SA Murray SA Blanchetown Weir – Lock 11 14,030
Bookpurnong Weir – Lock 41 7,949
Lake Albert1 187,353
Lake Alexandrina1 705,463
Overland Weir – Lock 31 13,703
Renmark Weir – Lock 51 9,445
Upstream of Lock 6 (Murtho)2 14,451
Upstream of Lake Alexandrina2 50,509
Waikerie Weir – Lock 21 13,082
SW1 ACT SS1 ACT ACT Bendora Reservoir1 667
Corin Reservoir1 2,879
Cotter Reservoir1 362
Googong Reservoir1 7,994
Lake Burley Griffin 2 6,330
Lake Ginninderra2  1,106
Lake Tuggeranong2 759
Southern Basin

2,892,164

Whole MDB region

3,258,419

1 Dynamic surface area was used in calculations

2 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])

 

Quantification approach

Data source

The Bureau: (a) National Climate Centre (NCC) daily climate grids (rainfall, temperature and solar radiation), (b) AHGF waterbody feature class, and (c) Australian water resources information system (AWRIS) water storage.

Provided by

The Bureau.

Method

The potential evaporation estimate produced by the Australian Water Resources Assessment system landscape model (AWRA-L) version 2.0.0 (Van Dijk 2010) was used to calculate evaporation from the surface water store. The AWRA-L model uses a modified version of the Penman–Monteith method to produce the potential evaporation. Daily AWRA-L potential evaporation grids were produced based on daily gridded climate data that were available on a 0.050 (approximately 5 km) national grid.

Potential evaporation was an estimate of the evaporative demand of the environment. The daily gridded climate data sets used to produce this estimate were generated by the Bureau and included downward solar irradiance, and maximum and minimum air temperature. The methods used to generate these gridded data-sets have been outlined in Jones et al. (2007).

The evaporation at each waterbody was estimated from the proportionally weighted average of grid-pixels cells that intersected each water feature. The volume was then estimated using the monthly average surface area of each waterbody. The surface area varied dynamically with changing level for storages 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.

Assumptions, limitations, caveats and approximations

  • The AWRA-L potential evaporation estimates are subject to approximations associated with interpolating the observation point input data to a national grid as described in Jones et al. (2007).
  • The dynamic storage surface areas calculated from the levels and storage rating tables represent a monthly average and therefore do not capture changes that occur on a shorter time-scale.
  • The use of the static default AHGF surface area is an approximation only. It represents the waterbody at capacity and therefore likely results in an overestimation of precipitation on those features.

Uncertainty information

The uncertainty estimate was not quantified.

Comparative year

The following changes resulted in the restatement of the 2010–11 year volume:

  • a change made to the calculation method
  • scope change.

The changes and their respective values are detailed in the following table.


Restatement of comparative year information made for the line item 17.1 Evaporation from surface water
Segment 2012 Account volume for the 2010–11 year (ML) 2011 Account volume for the 2010–11 year (ML) Difference due to calculation method and scope change (ML)
Northern Basin 320,996 372,396 -51,400
Southern Basin 2,692,725 3,133,172 -440,447
Whole region 3,013,721 3,505,568 -491,847

 

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 change due to the scope for the 2010–11 year is not available.

Calculation method change was due to selecting AWRA-L method in the 2012 Account instead of Priestly and Taylor potential evaporation method used for the 2011 Account. The change was made for better estimate of evaporation. Resulting volume change due to the calculation method change for the 2010–11 year was decrease of the volume by 491,847 ML which represents a change of 14% of the previously reported value.