Murray–Darling Basin

14.3.1 Groundwater recharge from connected surface water

Supporting information

The volumetric value for the line item is 204,390 ML (see the following table for the breakdown of the volume).

Groundwater recharge volumes from connected surface water in the Murray–Darling Basin (MDB) for 2009–10
Region no.	Groundwater management unit (GMU)	State	Volume (ML)
1	Lower Gwydir Alluvium	NSW	–
2	Lower Lachlan Alluvium	NSW	14,220
3	Upper Lachlan Alluvium	NSW	–
4	Lower Macquarie Alluvium	NSW	18,375
5	Lower Murray Alluvium	NSW	–
Lower Murrumbidgee – sum composed of GMUs 6 & 7			88,985
6	Lower Murrumbidgee Deep Groundwater source	NSW
7	Lower Murrumbidgee Shallow Groundwater source	NSW
8	Mid Murrumbidgee Alluvium	NSW	27,860
9	Lower Namoi Alluvium	NSW	37,300
10	Upper Namoi Alluvium	NSW	17,650
Katunga–Campaspe – sum composed of GMUs 11–13			–
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	–
Lower Murray–Darling Basin GMUs – sum composed of GMUs 15–27			–
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		204,390

– = no data available

These recharge volumes have only been calculated (using New South Wales groundwater models) for those New South Wales GMUs where a river is represented as a source of water to the groundwater system. Water flows from the river to the groundwater system when the water level surface of the river is higher than the water table surface.

Quantification approach

Data source

Groundwater recharge from connected surface water (river leakage) is a subroutine that can be activated in a groundwater model. Some of the New South Wales groundwater models have used this subroutine. Data inputs draw from knowledge of the hydrogeology and surface water processes to initialise parameters for river bed conductance and thickness.

Data provider

NSW Office of Water.

Method

MODFLOW representation of river leakage; see documentation at MODFLOW website of the United States Geological Survey (USGS).

Uncertainty

Uncertainty is ungraded. It is currently not feasible to estimate the uncertainty of a flux like river leakage within the MODFLOW groundwater model.

Approximation, assumptions, caveats/limitation

Groundwater models make numerous assumptions and approximations to represent water balance. Refer to the USGS website and associated references.