Murray-Darling Basin
17.1 Evaporation from surface water

The volumetric value for the line item at the end of the 2010–11 year was 3,505,568 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 evaporation volumes on surface water assets in the MDB region in the 2010–11 year

Surface water resource plan area		State	Volume (ML) for the 2010–11 year
Code	Name
SW18	Condamine–Balonne	Qld	76,744
SW16	Qld Border Rivers	Qld	46,482
SW15	NSW Border Rivers	NSW	14,798
SW14	Gwydir	NSW	38,835
SW13	Namoi	NSW	76,713
SW10	Macquarie–Castlereagh	NSW	118,824
Sub-total Northern Basin			372,396
SW9	Lachlan	NSW	137,885
SW8	Murrumbidgee NSW	NSW	129,225
SW7	NSW Murray and Lower Darling	NSW	1,153,414
SW3	Northern Victoria	Vic	325,367
SW2	Vic Murray	Vic	229,451
SW4	Wimmera–Mallee	Vic	49,578
SW5	SA Murray	SA	1,086,563
SW1	ACT	ACT	21,689
Sub-total Southern Basin			3,133,172
Total for the region			3,505,568

 

Specific details of evaporation volumes on individual surface water asset basis in the MDB region in the 2010–11 year

Water resource plan area	SDL area		State	Surface water asset	Volume (ML) for the 2010–11 year
	Code	Name
Condamine–Balonne	SS26	Condamine–Balonne	Qld	Buckinbah Weir1	3,228
				Chinchilla Weir1	4,395
				Connolly Dam2	606
				Cooby Creek Reservoir2	3,407
				Jack Taylor Weir1	4,847
				Lake Kajarabie1	44,965
				Lake Leslie1	13,474
				Moolabah Weir1	1,647
				Neil Turner Weir2	175
Qld Border Rivers	SS24	Qld Border Rivers	Qld	Glenlyon Lake1	22,377
				Lake Coolmunda1	22,824
				Storm King Dam2	1,281
NSW Border Rivers	SS23	NSW Border Rivers	NSW	Lake Inverell2	516
				Pindari Lake1	13,974
				Tenterfield Creek2	308
Gwydir	SS22	Gwydir	NSW	Lake Copeton1	37,533
				Tareelaroi Weir1	1,302
Namoi	SS21	Namoi	NSW	Chaffey Dam1	6,742
				Dungowen2	612
				Gunidgera Weir1	928
				Lake Keepit1	55,688
				Mollee Weir1	1,413
				Quipolly Dam2	1,500
				Split Rock Reservoir1	9,830
Macquarie–Castlereagh	SS20	Macquarie–Castlereagh	NSW	Chifley Dam2	3,205
				Lake Burrendong1	92,771
				Lake Oberon2	4,749
				Lake Windamere1	13,538
				Rylstone Reservoir2	1,134
				Spring Creek Reservoir2	969
				Suma Park Reservoir2	1,955
				Timor Dam2	246
				Winburndale Dam2	257
Northern Basin					372,396
Lachlan	SS16	Lachlan	NSW	Carcoar Lake1	2,665
				Lake Brewster1	62,120
				Lake Cargelligo1	20,403
				Lake Endeavour2	708
				Lake Rowlands2	943
				Lake Wyangala1	51,046
Murrumbidgee NSW	SS15	Murrumbidgee	NSW	Berembed Weir1	1,445
				Blowering Reservoir1	51,008
				Gogeldrie Weir1	2,738
				Hay Weir1	5,358
				Lake Burrinjuck1	62,238
				Maude Weir1	2,221
				Redbank Weir2	231
				Tombullen Storage1	3,986
NSW Murray and Lower Darling	SS18	Lower Darling	NSW	Lake Cawndilla1	176,014
				Lake Menindee1	242,027
				Lake Victoria1	152,419
				Lake Wetherell1	114,882
				Pamamaroo Lake1	103,364
				Stephens Creek Reservoir2	10,644
	SS14	NSW Murray	NSW	Lake Hume1	228,973
				Upstream of Lock 7 (Rufus)2	6,334
				Upstream of Lock 8 (Wangumma)2	9,141
				Upstream of Lock 9 (Kulnine)2	14,583
				Upstream of Lock 10 (Wentworth)2	13,087
				Upstream of Lock 15 (Euston)2	81,946
Vic Murray	SS3	Kiewa	Vic	Lake Guy2	98
				Rocky Valley Storage2	2,048
Northern Victoria	SS4	Ovens	Vic	Lake Buffalo1	2,929
				Lake William Hovell1	1,461
	SS5	Broken	Vic	Lake Nillahcootie1	6,162
	SS6	Goulburn	Vic	Goulburn Weir 1	13,130
				Greens Lake1	9,480
				Lake Eildon1	117,508
				Waranga Basin1	67,444
	SS7	Campaspe	Vic	Campaspe Weir2	284
				Lake Eppalock1	33,563
				Lauriston Reservoir2	2,362
				Malmsbury Reservoir2	3,167
				Upper Coliban Reservoir2	3,082
	SS8	Loddon	Vic	Barkers Creek Reservoir2	632
				Cairn Curran Reservoir1	18,908
				Crusoe Reservoir2	332
				Evansford Reservoir2	283
				Hepburn Lagoon2	986
				Kow Swamp2	29,262
				Laanecoorie Reservoir1	4,995
				Mccay2	198
				Newlyn Reservoir1	639
				Sandhurst Reservoir2	328
				Spring Gully Reservoir2	431
				Tullaroop Reservoir1	7,801
Vic Murray	SS2	Vic Murray	Vic	Kangaroo/Racecourse Lake2	14,432
				Lake Banimboola2	708
				Lake Dartmouth1	56,094
				Lake Mulwala1	52,584
				Mildura Weir2	1,572
				Reedy/Middle Lake2	4,747
				Third Lake2	2,750
				Torrumbarry Weir1	10,539
				Upstream of Lake Mulwala2	33,272
				Upstream of Mildura Weir2	50,607
Wimmera–Mallee	SS9	Wimmera–Mallee	Vic	Lake Bellfield1	3,825
				Lake Fyans1	4,359
				Lake Lonsdale1	25,552
				Lake Taylor1	5,505
				Lake Whitton2	882
				Toolondo Reservoir1	61
				Wartook Reservoir1	9,394
SA Murray	SS11	SA Murray	SA	Blanchetown Weir – Lock 11	17,010
				Bookpurnong Weir – Lock 41	9,099
				Lake Albert1	191,187
				Lake Alexandrina1	755,299
				Overland Weir – Lock 31	16,784
				Renmark Weir – Lock 51	10,905
				Upstream of Lock 6 (Murtho)2	17,238
				Upstream of Lake Alexandrina2	54,774
				Waikerie Weir  – Lock 21	14,267
ACT	SS1	ACT	ACT	Bendora Dam1	856
				Corin Dam1	2,948
				Cotter Dam1	471
				Googong Reservoir1	8,065
				Lake Burley Griffin2	7,241
				Lake Ginninderra2	1,249
				Lake Tuggeranong2	859
Southern Basin					3,133,172
Total for the region					3,505,568

¹ Dynamic surface area was used in calculations

² Static surface area was used in calculations (based on boundaries defined for surface water bodies in Bureau of Meteorology's Australian Hydrological Geospatial Fabric)

 

Bureau of Meteorology (the Bureau): (1) Rainfall, temperature and solar radiation grids, (2) Australian Hydrological Geospatial Fabric (AHGF) waterbody feature class and (3) Australian Water Resources Information System (AWRIS) water storage.

The Bureau.

The Priestly and Taylor method to estimate potential evaporation (as calculated by the WaterDyn model [Raupach 2008]) was used to estimate evaporation from the surface water assets. Monthly potential evaporation data produced by the Bureau were used, based on daily gridded climate data that is available on a 0.05 degree (approximately 5 km) national grid.

Potential evaporation is an estimate of the evaporative demand of the environment. The daily gridded climate data sets used to produce this estimate are generated by the Bureau and include downward solar irradiance, and maximum and minimum air temperature. The methods used to generate these gridded data-sets are 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.

The Priestly and Taylor method 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 uncertainty estimate was not quantified.

This line item corresponds to line item 14.1 Evaporation from connected surface water, reported in the 2010 Account. In the 2011 Account, the following changes were made that caused the 2009–10 year value to be restated:

•  The scope of the line item was changed.

• An error was committed in the values reported in the 2010 Account.

• The methodology used to quantify the line item was improved and resulted in a material change in volume.

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

2010 Account line items	Segment	Volume for the 2009–10 year reported in the 2010 Account (ML)	Difference due to scope, prior period error correction and calculation method change (ML)	Volume for the 2009–10 year reported in the 2011 Account (ML)
14.1 Evaporation from connected surface water	Northern Basin	261,749	–57,603	204,146
	Southern Basin	2,896,721	–423,914	2,472,807
	Whole region	3,158,470	–481,517	2,676,953

Scope change was due to the following reasons:

• Lake Mokoan, Lake Batyo Catyo, Pine Lake, Dock Lake and Green Lake (included in the 2010 Account) were excluded for the 2011 Account.  Information for Lake Mokoan was not available.  Qualification of other four storages as surface water asset was not verified at the data collection phase for the 2011 Account (they were considered as abandoned after the construction of Wimmera pipeline).  For 2012 Account, these storages will be investigated for their inclusion.

• Regulated river reaches upstream of Lock 10 and Lock 15 in the River Murray were included for the 2011 Account.

Prior period error correction was due to the following reason:

• Barren Box Swamp was included in the 2010 Account.  However, it is not a surface water asset for the 2011 Account because this storage is located in a water distribution system.  Barren Box Swamp was excluded in the 2011 Account.

Calculation method change was due to the following reason:

• Penman open water evaporation method was used for the 2010 Account. For the 2011 Account, Priestly and Taylor potential evaporation method was used.  The change was made for better estimate of evaporation.