Murray–Darling Basin
30.3 Runoff harvesting into off-channel water store

The volumetric value for the line item for the 2012–13 year was 1,045,619 ML. The line item includes collection of runoff into off-channel water storages including local catchment runoff into off-channel water storages within the Murray–Darling Basin (MDB) region. The following table presents breakdown information for the volumetric value on a surface water resource plan area basis.

 

Runoff harvesting into off-channel water storages in the MDB region for the 2012–13 year

Water resource plan area	Sustainable diversion limit area		State/Territory	Volume (ML) for the 2012–13 year
	Code	Name
SW20 Warrego–Paroo–Nebine	SS29	Paroo	Qld	207,232
	SS28	Warrego	Qld
	SS27	Nebine	Qld
SW19 Condamine–Balonne	SS26	Condamine–Balonne	Qld
SW18 Moonie	SS25	Moonie	Qld
SW12 Barwon–Darling Watercourse	SS19	Barwon–Darling Watercourse	NSW
SW13 NSW Intersecting Streams	SS17	NSW Intersecting Streams	NSW
SW17 Qld Border Rivers	SS24	Qld Border Rivers	Qld	102,313
SW16 NSW Border Rivers	SS23	NSW Border Rivers	NSW
SW15 Gwydir	SS22	Gwydir	NSW	56,140
SW14 Namoi	SS21	Namoi	NSW	72,249
SW11 Macquarie–Castlereagh	SS20	Macquarie–Castlereagh	NSW	148,047
Sub-total Northern Basin				585,981
SW10 Lachlan	SS16	Lachlan	NSW	136,483
SW9 Murrumbidgee	SS15	Murrumbidgee  NSW	NSW	119,825
SW1 ACT	SS1	ACT	ACT
SW8 NSW Murray and Lower Darling	SS18	Lower Darling	NSW	68,819
	SS14	NSW Murray	NSW
SW2 Vic. Murray	SS3	Kiewa	Vic.
	SS2	Vic Murray	Vic.
SW4 Wimmera–Mallee	SS9	Wimmera–Mallee	Vic.
SW5 SA Murray Region	SS10	SA Non-prescribed areas	SA
SW6 SA River Murray	SS11	SA Murray	SA
SW3 Northern Victoria	SS4	Ovens	Vic.	22,626
	SS5	Broken	Vic.	64,100
	SS6	Goulburn	Vic.
	SS7	Campaspe	Vic.	12,615
	SS8	Loddon	Vic.	22,824
SW7 Eastern Mount Lofty Ranges	SS13	Eastern Mount Lofty Ranges	SA	12,346
	SS12	Marne Saunders	SA
Sub-total Southern Basin				459,638
Whole MDB region				1,045,619

    

(1) Bureau of Meteorology (the Bureau): National Climate Centre daily climate grids (rainfall, temperature and solar radiation); and (2) Geoscience Australia: MDB human-made waterbody feature class and nine arc-second digital elevation model (DEM).

The Bureau.

Rainfall runoff harvesting to off-channel water storages was estimated using the Australian water resources assessment system landscape (AWRA-L) version 3.0 model, and the water-balance based farm dam algorithm written by the bureau.

Using climate grid data for the MDB region (including precipitation, temperature, and solar radiation data), AWRA-L (Van Dijk 2010) was used to estimate the runoff depth at each grid-point within the region.

The MDB was divided into 105 regions for the purpose of modelling the off-channel water store. The off-channel water store consisted of storages filled primarily by local catchment runoff. These were determined from waterbody mapping conducted by Geoscience Australia as those which:

• are not named storages (assuming that any storage with a name is unlikely to be a off-channel water storage); and
• are above 600 m in elevation; and/or
• are below 600 m in elevation in areas that receive greater than 400 mm per annum in precipitation and are not within 50 m of a major or perennial stream.

The above rules attempt to divide storages into those that are likely to be filled primarily by local catchment runoff and those which are filled by abstraction from surface water, groundwater or floodplain harvesting. The catchment of each individual storage was determined via analysis of the 9 arc-second DEM.

The average runoff depth across the MDB sub-regions was determined as the weighted mean of runoff 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 is not wholly within the MDB region) and the effect of changing area represented with changing latitude. The average runoff depth was converted to a volume by multiplying depth by the total area and was used as an input into the farm dam algorithm.

• The gridded climate input data are subject to approximations associated with interpolating observation point data to a national grid detailed in Jones et al. (2007).
• The spatial extent of water bodies subject to the assumptions and methods associated with the data provided by the Geoscience Australia.
• The use of a 9 arc-second DEM to determine catchment area may result in storages being assigned a catchment much larger or smaller than the true catchment. In some cases a storage may be assigned the catchment of a stream line hundreds of metres away.

The uncertainty estimate was not quantified.