Sydney
17.1 Evaporation from surface water
Supporting Information
The following tables provide a summary and breakdown of evaporation from surface water in the Sydney region.
Connected surface water asset |
Evaporation from the asset during 2010–11 (ML) |
Storages managed by the Sydney Catchment Authority |
95,911 |
Storages not managed by the Sydney Catchment Authority |
5,568 |
River sections |
13,415 |
Total |
114,894 |
Storage reservoir |
Evaporation during 2010–11 (ML) |
Cataract |
6,274 |
Cordeaux |
4,598 |
Avon |
7,087 |
Nepean |
5,340 |
Woronora |
1,496 |
Lake Burragorang (Warragamba Dam) |
46,196 |
Prospect |
5,340 |
Wingecarribee |
5,759 |
Fitzroy Falls |
5,492 |
Lake Yarrunga (Tallowa Dam) |
8,050 |
Blue Mountains1 |
279 |
Total |
95,911 |
1Blue Mountains storages include Medlow Reservoir, Greaves Creek Reservoir, Upper Cascade Reservoir, Middle Cascade Reservoir and Lower Cascade Reservoir.
Storage reservoir1 |
Managing authority |
Evaporation during 2010–11 (ML) |
Bamarang |
Shoalhaven City Council |
765 |
Danjera |
Shoalhaven City Council |
938 |
Flat Rock Creek |
Shoalhaven City Council |
259 |
Pejar |
Goulburn Mulwaree Council |
1,768 |
Sooley |
Goulburn Mulwaree Council |
1,344 |
Farmers Creek No. 2 |
Lithgow City Council |
77 |
Medway |
Wingecarribee Shire Council |
216 |
Bundanoon |
Wingecarribee Shire Council |
201 |
Total |
5,568 |
1Data were calculated by the Bureau of Meteorology. Data for storage reservoirs not listed in this disclosure note are not available.
River1 |
From |
To |
Evaporation during 2010–11 (ML) |
Capertee |
Glen Davis |
Upper Colo |
1,275 |
Coxs |
Lithgow |
Kelpie Point |
1,788 |
Macdonald |
Howes Valley |
St Albans |
195 |
Shoalhaven |
Kadoona |
Fossickers Flat |
4,203 |
Wollondilly |
Pomeroy |
Golden Valley |
5,954 |
Total |
13,415 |
1Data were calculated by the Bureau of Meteorology. Only the river sections for which river volumes have been calculated are included.
Quantification Approach
Bureau of Meteorology
Data Source
Provided by
Method
The Priestly and Taylor method (Raupach 2008) to estimate potential evaporation (as calculated by the WaterDyn model) was used to estimate evaporation from the surface water store. Monthly potential water evaporation data produced by the Bureau of Meteorology were used, based on daily gridded climate data that are available on a 0.05 degree (5 km) national grid.
Potential evaporation is an estimate of the evaporative demand of the environment. The daily gridded climate datasets 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 datasets are outlined in Jones et al. (2007).
The evaporation at each waterbody was estimated from the proportionally weighted average of grid-pixels 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 reservoir storage level for storages where the relationship between storage level and surface area had been derived.
Assumptions, Limitations, Caveats and Approximations
- The Priestly and Taylor method for 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.
- The dynamic storage surface areas calculated from the levels and storage rating tables represent a monthly average and therefore will not capture changes that occur on a shorter timescale.
- The total surface area of the surface water store within the Sydney region included only the storages, urban storages and weirs listed in the supporting information.
Uncertainty Information
Uncertainty was not quantified.
Sydney Catchment Authority
Data Source
Provided by
Method
Measured pan evaporations were adjusted by a pan factor.
Assumptions, Limitations, Caveats and Approximations
Uncertainty Information
The evaporation volume is based on measured data. Estimated uncertainty based on measurement accuracy, professional judgment on the calculation method and organisational practice is +/– 10%.
Comparative year
The following table compares the value at 30 June 2010 reported in this account with the corresponding value reported in the 2010 Account.
2011 Account line item |
2010 Account line item |
Value reported in the 2010 Account (ML) |
Value reported in the 2011 Account (ML) |
Additional information |
17.1 Evaporation from surface water |
14.1 Evaporation from connected surface water |
130,565 |
130,565 |
Change in line item name and number |