Murray–Darling Basin

15.1.3 Other lumped groundwater inflow from outside entity

Supporting information

The volumetric value for the line item is 10,400 ML (see the following table for the breakdown of the volume). The primary source of this groundwater flow into the region is via flow upwards from aquifers of the Great Artesian Basin (GAB) into sediments within the region.

Upward flow into the Murray–Darling Basin (MDB) sediments from the underlying aquifers of the Great Artesian Basin, detailed per groundwater management unit in 2009–10
No.	Groundwater management unit (GMU)	State	Volume 2009–10 (ML)	Quantification method
1	Lower Gwydir Alluvium	NSW	–	n/a
2	Lower Lachlan Alluvium	NSW	–	n/a
3	Upper Lachlan Alluvium	NSW	–	n/a
4	Lower Macquarie Alluvium	NSW	–	n/a
5	Lower Murray Alluvium	NSW	–	n/a
Lower Murrumbidgee – sum composed of GMUs 6 & 7			–	n/a
6	Lower Murrumbidgee Deep Groundwater source	NSW
7	Lower Murrumbidgee Shallow Groundwater source	NSW
8	Mid Murrumbidgee Alluvium	NSW	–	n/a
9	Lower Namoi Alluvium	NSW	10,400	Input to NSW groundwater model
10	Upper Namoi Alluvium	NSW	–	n/a
Katunga–Campaspe – sum composed of GMUs 11–13			–	n/a
11	Campaspe Deep Lead Water Supply Protection Area	Vic
12	Katunga Water Supply Protection Area	Vic
13	Shepparton Irrigation Water Supply Protection Area	Vic
14	Mid Loddon Water Supply Protection Area	Vic	–	n/a
Lower Murray–Darling Basin GMUs – sum composed of GMUs 15–27			–	n/a
15	Balrootan (Nhill) Groundwater Management Area	Vic
16	Goroke Groundwater Management Area	Vic
17	Kaniva TCSA Groundwater Management Area	Vic
18	Murrayville Water Supply Protection Area	Vic
19	Nhill Groundwater Management Area	Vic
20	Telopea Downs Water Supply Protection Area	Vic
21	Angas–Bremer Prescribed Wells Area	SA
22	Coorong	SA
23	Ferries–McDonald	SA
24	Mallee Prescribed Wells Area	SA
25	Murraylands	SA
26	Peake, Roby and Sherlock Prescribed Wells Area	SA
27	River Murray Prescribed Water Course	SA
	Total Basin		10,400

– = no data available; n/a = not applicable

Quantification approach

Data source

Output from the Lower Namoi groundwater model.

Data provider

NSW Office of Water.

Method

The Lower Namoi groundwater model is constructed as a MODFLOW model (USGS 2011). Leakage upwards from the GAB aquifers that underlie the deepest modelled layer is represented as an upward flux into the deepest layer in the model area where this process is known to occur.

Uncertainty

Uncertainty is ungraded.

Approximations, assumptions, caveats/limitations

Groundwater models are approximate numerical representations of groundwater systems. The accuracy of the leakage rate from the GAB to the MDB sediments is unknown. The leakage was estimated so that the modelled groundwater levels within the deepest model layer would match measured levels in this layer as closely as possible during a calibration period of approximately 20 years.