Groundwater Resources

Victoria's Groundwater Resources.

Major studies undertaken on the hydrogeology of the Murray Basin in North Central Victoria include those by Lawrence (1975), Macumber (1983) and Tickell and Humphreys (1987). Groundwater in the North Central catchment is extensively utilised for stock and irrigation purposes and, increasingly, for town water supplies. It has been intensively investigated, particularly in terms of its role in land and water salinity.

The basal aquifer system in the Murray Basin is the fluviatile Renmark Group, which consists of the Warina Sand, which is dominantly a quartz sand, and the younger Olney Formation, which tends to be more carbonaceous and silty to clayey. The Olney Formation is the lesser aquifer of the two units in the Renmark Group. Aquifers in these units are confined beneath the overlying thick sequence of the Geera Clay and Ettrick Marl aquitards. Groundwater flow is mainly north and north-westerly and salinities in the Renmark Group increase along flow paths from around 1 000 mg/L Total Dissolved Solids (TDS) around the highland front up to 12 000 mg/L TDS. Bore yields up to 50 L/sec have been obtained, but because of its greater relative depth, the Renmark Group aquifer has not been exploited.

The sands and gravels of the Calivil Formation infilled the former valleys of the Avoca, Loddon and Campaspe drainage systems that were incised into the Renmark Group. The aquifer is well developed close to the highlands where coarser grained sediments were deposited. The aquifer becomes increasingly more confined to the north, however, bore yields up to 125 L/sec have previously been obtained. Groundwater salinity to the highland front is usually less than 500 mg/L TDS but increases to the north along flow paths to be highly saline (up to 40 000 mg/L) beneath much of the Riverine Plain. Groundwater from the Calvil Formation is exploited around the Basin margins for irrigation and stock water but it becomes too saline for irrigation beyond about 80 km of the highland front.

Source: Leonard (1992).

In the Avon-Richardson catchment, groundwater usage generally ranges from stock quality to salt farming potential. The Avoca catchment's groundwater resources are not well documented but stock use is a reasonably common application. Irrigation potential also exists in the Natte Yallock-Rathscar area and in the Wooroonook Lakes/ Glenloth areas. Groundwater resources are generally of significantly higher quality in the Campaspe and Loddon catchments and the uses are more diverse than in the other North Central catchments. Good underutilised resources still exist in some of the extensive deep lead deposits, particularly in the Loddon, south of Serpentine and north to Creswick. Such resources also exist in the Campaspe, between Diggorra and Axedale. To the north of both of these areas (ie: the lower Campaspe and Loddon plains), groundwater resources are either unsuitable for irrigation or else they are mostly at (or above) there sustainable level of usage.

Source: Mark Reid, pers. comm.

References

Lawrence, C.R., (1975). Geology, hydrodynamics and hydrochemistry of the Southern Murray Basin. Geol. Surv. Victoria, Memoir 30, vol. 1, Rept. Vol 2.

Leonard, J., (1992). Drought Management Plan for Victoria’s Water Resources: An Overview of Victoria’s Groundwater Resources. Department of Water Resources, Melbourne.

Macumber P.G., (1983). Interaction between groundwater and surface systems in northern Victoria. PhD thesis, University of Melbourne (unpubl.).

Mark Reid, Centre for Land Protection Research, personal communication.

Tickell S.J. and Humphrys W.G., (1987). Groundwater resources and associated salinity problems of the Victorian part of the Riverine Plain. Vic. Geol. Surv., Rep. no. 84.

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