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

A low-salinity (total dissolved solids, 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 ra...

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Bibliographic Details
Published in:Journal of hydrology (Amsterdam) 2010-01, Vol.380 (1), p.203-221
Main Authors: Cartwright, Ian, Weaver, Tamie R, Simmons, Craig T, Fifield, L Keith, Lawrence, Charles R, Chisari, Robert, Varley, Simon
Format: Article
Language:English
Subjects:
aquifers
base flow
Baseflow
carbon
Channels
Dynamical systems
Earth sciences
Earth, ocean, space
Environmental isotopes
Exact sciences and technology
Freshwater
Groundwater
groundwater lens
groundwater recharge
Hydraulics
hydrochemistry
Hydrology. Hydrogeology
ions
Lenses
oxygen
radionuclides
Recharge
Regional
Rivers
Sands
stable isotopes
Surface water
tritium
water table
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Summary:A low-salinity (total dissolved solids, 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.
ISSN:0022-1694
1879-2707
DOI:10.1016/j.jhydrol.2009.11.001