Adelaide
18.4 Discharge to surface water

Supporting information

The volume reported (72,148 ML) represents annual average groundwater discharge (baseflow) to watercourses in the Adelaide region. This volume included annual baseflow from groundwater to watercourses within the Western Mount Lofty Ranges Prescribed Water Resources Area (70,655 ML) and baseflow at the Yaldara gauging station on the North Para River (1,493 ML) as shown in the following table.

 

Groundwater discharge to surface water itemised by underground water management zones
Underground water management zones

Baseflow (ML)

Lower South Para (inc. Lower Gawler River)

1,351

Middle South Para River

3,784

Upper South Para River (Adelaidean)

1,538

Upper South Para River (Kanmantoo)

660

Gould Creek

460

Little Para Reservoir

209

Lower Little Para River

87

Upper Little Para River

1,407

Kersbrook Creek

1,428

Mount Pleasant

300

Birdwood

1,273

Hannaford Creek

416

Angas Creek

587

Millers Creek

604

Gumeracha

1,079

McCormick Creek

257

Footes Creek

283

Kenton Valley

420

Cudlee Creek

882

Kangaroo Creek Reservoir

1,330

Sixth Creek

2,809

Charleston Kanmantoo

652

Inverbrackie Creek Kanmantoo

305

Charleston Adelaidean

979

Inverbrackie Creek Adelaidean

567

Mitchell Creek

155

Western Branch

998

Lenswood Creek

2,182

Upper Onkaparinga

1,906

Balhannah

220

Hahndorf

355

Cox Creek

2,029

Aldgate Creek

1,846

Scott Creek

1,487

Chandlers Hill 

373

Mount Bold Reservoir

2,644

Biggs Flat

323

Echunga Creek

1,063

Myponga Adelaidean

1,781

Myponga Sedimentary

3,303

Hindmarsh Fractured Rock

6,484

Hindmarsh Tiers Sedimentary

1,372

Fleurieu Permian

6,781

Southern Fleurieu North

4,013

Southern Fleurieu South

7,673

Western Mount Lofty Ranges Subtotal

 70,655

North Para River at Yaldara 

1,493

Total

72,148

Quantification approach

Data source

Hydstra database, and draft water allocation plan for the Western Mount Lofty Ranges Prescribed Water Resources Area (PWRA).

Provided by

South Australian Department of Environment, Water and Natural Resources (DEWNR).

Method

Groundwater discharge to surface water was summed from the annual baseflow figures stated in the draft water allocation plan for the Western Mount Lofty Ranges PWRA (70,655 ML) and baseflow at the Yaldara gauging station on the North Para River (1,493 ML).

The stream gauge for the North Para River at Yaldara (A5050502) was deemed the only streamflow site with a significant baseflow component outside the WMLR PWRA. Baseflow was calculated for this site using a Lyne and Hollick filter (Grayson et al. 1996) with a filtering factor of 0.925 and daily flow records for 1 July 1975 – 30 June 2010.

Assumptions, limitations, caveats and approximations

  • Baseflow at the gauging stations captured all the surface water—groundwater interactions in the catchment.
  • Baseflow identified by the Lyne and Hollick filter was entirely due to contributions from groundwater.
  • Long-term baseflow represents the flux during the 2011–12 year.
  • Groundwater discharge to connected surface water was the dominant process in the WMLR.
  • Surface water—groundwater interactions outside the draft WMLR PWRA and the catchment for Yaldara gauge are negligible.

Uncertainty information

The uncertainty estimate is not quantified.