29.1 Evaporation from landscape
The volumetric value for the line item for the 2010–11 year was 746,945,199 ML. The line item represents the volume of water that passes into the atmosphere across a water/air interface including evaporation from the landscape within the Murray–Darling Basin (MDB) region. The following table presents breakdown information for the volumetric value on sustainable diversion limit (SDL) area basis.
|Water resource plan area||
|SW19 Warrego – Paroo – Nebine||SS29||Paroo||Qld||18,837,767|
|SW16 Qld Border Rivers||SS24||Qld Border Rivers||Qld||19,330,565|
|SW15 NSW Border Rivers||SS23||NSW Border Rivers||NSW||17,886,219|
|SW11 Barwon–Darling Watercourse||SS19||Barwon–Darling Watercourse||NSW||2,095,043|
|SW12 NSW Intersecting Streams||SS17||NSW Intersecting Streams||NSW||70,437,836|
|Sub-total Northern Basin||404,453,341|
|SW8 Murrumbidgee||SS15||Murrumbidgee NSW||NSW||65,377,718|
|SW7 NSW Murray and Lower Darling||SS18||Lower Darling||NSW||62,486,585|
|SW2 Vic Murray||SS3||Kiewa||Vic||1,976,906|
|SW3 Northern Victoria||SS4||Ovens||Vic||7,890,870|
|SW2 Vic Murray||SS2||Vic Murray||Vic||14,026,753|
|SW6 Eastern Mount Lofty Ranges||SS13||Eastern Mount Lofty Ranges||SA||1,794,284|
|SW5 SA Murray||SS11||SA Murray||SA||697,952|
|SS10||SA Non-prescribed areas||SA||33,897,131|
|SW6 Eastern Mount Lofty Ranges||SS12||Marne–Saunders||SA||444,387|
|Sub-total Southern Basin||342,491,858|
|Total for the region||746,945,199|
Evapotranspiration from the landscape was estimated based on the AWRA-L version 1.0.0 (Van Dijk 2010) model outputs.
Using climate grid data for the Murray–Darling Basin region (including precipitation, temperature and solar radiation data), AWRA-L was used to estimate the evapotranspiration depth at each grid-point within the region. Only evapotranspiration from the landscape was considered; evapotranspiration from storages, lakes, off-channel water storages and other water bodies was not included.
The average evapotranspiration depth across the MDB landscape was determined as the weighted mean of evapotranspiration occurring from the relevant grid points within the region boundary. Points were weighted upon the area they represented within the MDB landscape to remove edge effects (where the area represented was not wholly within the MDB region) and the effect of changing area represented with changing latitude. The depth of evapotranspiration was converted to a volumetric estimate by multiplying by the total area of the MDB landscape.
Assumptions, Limitations, Caveats and Approximations
The gridded climate input data were subject to approximations associated with interpolating observation point data to a national grid detailed in Jones et al. (2007).
The uncertainty estimate was not quantified.