Physical hydrogeology and environmental isotopes to constrain the age, origins, and stability of a low-salinity groundwater lens formed by periodic river recharge: Murray Basin, Australia.

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dc.contributor.authorCartwright, Ien_AU
dc.contributor.authorWeaver, TRen_AU
dc.contributor.authorSimmons, CTen_AU
dc.contributor.authorFifield, LKen_AU
dc.contributor.authorLawrence, CRen_AU
dc.contributor.authorChisari, Ren_AU
dc.contributor.authorVarley, Sen_AU
dc.date.accessioned2010-04-20T02:01:39Zen_AU
dc.date.accessioned2010-04-30T05:08:51Zen_AU
dc.date.available2010-04-20T02:01:39Zen_AU
dc.date.available2010-04-30T05:08:51Zen_AU
dc.date.issued2010-01-15en_AU
dc.date.statistics2010-01-15en_AU
dc.description.abstractA low-salinity (total dissolved solids, TDS, <5000 mg/L) groundwater lens underlies the Murray River in the Colignan–Nyah region of northern Victoria, Australia. Hydraulic heads, surface water elevations, δ18O values, major ion geochemistry, 14C activities, and 3H concentrations show that the lens is recharged from the Murray River largely through the riverbank with limited recharge through the floodplain. Recharge of the lens occurs mainly at high river levels and the low-salinity groundwater forms baseflow to some river reaches during times of low river levels. Within the lens, flow through the shallow Channel Sands and deeper Parilla Sands aquifers is sub-horizontal. While the Blanchetown Clay locally separates the Channel Sands and the Parilla Sands, the occurrence of recently recharged low-salinity groundwater below the Blanchetown Clay suggests that there is considerable leakage through this unit, implying that it is not an efficient aquitard. The lateral margin of the lens with the regional groundwater (TDS >25,000 mg/L) is marked by a hectometer to kilometer scale transition in TDS concentrations that is not stratigraphically controlled. Rather this boundary represents a mixing zone with the regional groundwater, the position of which is controlled by the rate of recharge from the river. The lens is part of an active and dynamic hydrogeological system that responds over years to decades to changes in river levels. The lens has shrunk during the drought of the late 1990s to the mid 2000s, and it will continue to shrink unless regular high flows in the Murray River are re-established. Over longer timescales, the rise of the regional water table due to land clearing will increase the hydraulic gradient between the regional groundwater and the groundwater in the lens, which will also cause it to degrade. Replacement of low-salinity groundwater in the lens with saline groundwater will ultimately increase the salinity of the Murray River reducing its utility for water supply and impacting riverine ecosystems. © 2010, Elsevier Ltd.en_AU
dc.identifier.citationCartwright, I., Weaver, T. R., Simmons, C. T., Fifield, L. K., Lawrence, C. R., Chisari, R., & Varley, S. (2010). Physical hydrogeology and environmental isotopes to constrain the age, origins, and stability of a low-salinity groundwater lens formed by periodic river recharge: Murray Basin, Australia. Journal of Hydrology, 380(1-2), 203-221. doi:10.1016/j.jhydrol.2009.11.001en_AU
dc.identifier.govdoc1570en_AU
dc.identifier.issn0022-1694en_AU
dc.identifier.issue1-2en_AU
dc.identifier.journaltitleJournal of Hydrologyen_AU
dc.identifier.pagination203-221en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.jhydrol.2009.11.001en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/3243en_AU
dc.identifier.volume380en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectGround wateren_AU
dc.subjectSurface watersen_AU
dc.subjectGroundwater rechargeen_AU
dc.subjectAustraliaen_AU
dc.subjectSalinityen_AU
dc.subjectRiversen_AU
dc.titlePhysical hydrogeology and environmental isotopes to constrain the age, origins, and stability of a low-salinity groundwater lens formed by periodic river recharge: Murray Basin, Australia.en_AU
dc.typeJournal Articleen_AU
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