Murray-Darling Basin
26.1 Soil moisture

The volumetric value for the line item for the 2010–11 year was 175,048,227 ML. The line item represents the volume of water in the unsaturated zone in the soil profile within the Murray–Darling Basin (MDB) region.  The following table presents breakdown information for the volumetric value on sustainable diversion limit (SDL) area basis.

 

Volume of water in the unsaturated zone in the soil profile in the MDB region at 30 June 2011

Water resource plan area	SDL area		Jurisdiction	Volume (ML)
	Code	Name
SW19 Warrego – Paroo – Nebine	SS29	Paroo	Qld	4,702,246
	SS28	Warrego	Qld	11,621,548
	SS27	Nebine	Qld	6,126,940
SW18 Condamine–Balonne	SS26	Condamine–Balonne	Qld	15,664,300
SW17 Moonie	SS25	Moonie	Qld	2,480,692
SW16 Qld Border Rivers	SS24	Qld Border Rivers	Qld	4,019,058
SW15 NSW Border Rivers	SS23	NSW Border Rivers	NSW	3,875,799
SW11 Barwon–Darling Watercourse	SS19	Barwon–Darling Watercourse	NSW	571,622
SW12 NSW Intersecting Streams	SS17	NSW Intersecting Streams	NSW	17,715,954
SW14 Gwydir	SS22	Gwydir	NSW	5,302,173
SW13 Namoi	SS21	Namoi	NSW	7,450,351
SW10 Macquarie–Castlereagh	SS20	Macquarie–Castlereagh	NSW	16,398,819
Sub-total Northern Basin				95,929,502
SW9 Lachlan	SS16	Lachlan	NSW	14,273,316
SW8 Murrumbidgee	SS15	Murrumbidgee NSW	NSW	14,974,708
SW7 NSW Murray and Lower Darling	SS18	Lower Darling	NSW	13,400,303
	SS14	NSW Murray	NSW	3,158,297
SW2 Vic Murray	SS3	Kiewa	Vic	406,750
SW3 Northern Victoria	SS4	Ovens	Vic	1,659,428
	SS5	Broken	Vic	896,298
	SS6	Goulburn	Vic	3,441,557
	SS7	Campaspe	Vic	829,279
	SS8	Loddon	Vic	2,581,609
SW2 Vic Murray	SS2	Vic Murray	Vic	2,827,490
SW4 Wimmera–Mallee	SS9	Wimmera–Mallee	Vic	10,968,204
SW6 Eastern Mount Lofty Ranges	SS13	Eastern Mount Lofty Ranges	SA	609,657
SW5 SA Murray	SS11	SA Murray	SA	169,846
	SS10	SA Non-prescribed areas	SA	8,371,083
SW6 Eastern Mount Lofty Ranges	SS12	Marne–Saunders	SA	137,151
SW1 ACT	SS1	ACT	ACT	413,747
Sub-total Southern Basin				79,118,725
Total for the region				175,048,227

 

Data sources were (1) Bureau of Meteorology (the Bureau): National Climate Centre (NCC): daily climate grids (rainfall, temperature and solar radiation); Australian Hydrological Geospatial Fabric (AHGF), waterbody feature class, and (2) Commonwealth Scientific and Industrial Research Organisation (CSIRO): Australian water resource assessment – landscape (AWRA-L) model parameters; monthly climatological average radiation grids data.

The Bureau.

Soil moisture for the MDB region was estimated based on the AWRA-L version 1.0.0 (Van Dijk 2010) surface soil, shallow soil and deep soil moisture model outputs.

Using climate grid data for the MDB region (including precipitation, temperature and solar radiation data), AWRA-L was used to estimate the soil moisture for each soil layer at each grid-point within the region. Only soil moisture within the landscape was considered; therefore, the surface areas of the major storages, lakes, off-channel water storages and other waterbodies were excluded from the analysis.

The total depth of water in all three layers of the soil column at each grid point was extracted. This depth was then multiplied by the surface area represented by each individual grid point to give a volumetric estimate for every grid point. The volume for each grid point was summed up to provide an estimate of soil moisture for the entire MDB landscape.

The values provided in this note have not been compared to any real time measured data for the 2010–11 year.

The soil moisture estimates are subject to the assumptions of the AWRA-L v1.0.0 model detailed in Van Dijk (2010).

AWRA-L does not account for application of water via irrigation and lateral flow.

The uncertainty estimate was not quantified.

There was no comparative line item in the 2010 Account.  The relevant volume calculated for the 2009–10 year was 184,799,454 ML.