CRC LEME
Open File Report 180
ABSTRACT
Combing Geology and Geophysics to Develop a Hydrogeologic Framework
for salt interception in the Loxton Sands Aquifer, Central Murray
Basin, Australia
T.J. Munday, A.J. Hill, T. Wilson, B. Hopkins, A.L. Telfer,
G.J. White and A.A. Green
CRC LEME OPEN FILE REPORT 180 /
CSIRO Exploration and Mining Report P2004/86
EXECUTIVE SUMMARY
Salt interception schemes (SIS) have been developed to manage
high salt loads and to improve the health of the River Murray, both
in the Riverland (South Australia) and Sunraysia (Victoria/NSW)
areas. Currently SIS at Loxton and Bookpurnong are being developed,
both incorporating borefields in the Loxton Sands aquifer to intercept
saline groundwater flux from groundwater mounds that have formed
beneath irrigated areas. At Bookpurnong a sedimentological model
that defines lateral and vertical changes in facies associated with
the main aquifer systems relevant to the IS, has been refined from
a detailed interpretation of borehole geology, ground and airborne
geophysics, combined with the analysis of sediments for the Loxton
Sands and underlying Bookpurnong This is an important precursor
in the development of a predictive model of groundwater hydraulic
properties using available hydrogeological and geophysical data.
Definition of the sedimentological characteristics and depositional
setting of the principal aquifer system – the Loxton Sands,
has been critical. Relatively narrow zones of high transmissivity,
characterized by slightly reduced electrical conductivity response
at the watertable, are the target for ground TEM geophysical traverses.
These zones have been identified as elements of a Basin-wide beach-barrier
strandline sequence that developed in the Pliocene. Results from
the constrained inversion of helicopter EM data have helped to better
define the geometry of this sedimentary system and together with
a hydrogeological interpretation have contributed to a more informed
approach to the design, development and potential performance of
the Loxton Sands SIS borefields.
Keywords: Salt Interception Scheme, geophysics, Loxton Parilla
Sands, aquifers, groundwater
|
