Authors / CoAuthors
Raiber, M. | Lewis, S. | Cendon, D.I. | Cui, T. | Cox, M.E. | Gilfedder, M. | Rassam, D.W.
Abstract
Catchment-scale hydrological and hydrogeological investigations commonly conclude by finding that particular stream reaches are either gaining or losing; they also often assume that the influence of bedrock aquifers on catchment water balances and water quality is insignificant. However, in many cases, such broad findings are likely to oversimplify the spatial and temporal complexity of the connections between the different hydrological system components, particularly in regions dominated by cycles of droughts and flooding. From a modelling perspective, such oversimplifications can have serious implications on the process of identifying the magnitude and direction of the exchange fluxes between the surface and groundwater systems. In this study, we use 3D geological modelling and historic water chemistry and hydraulic records to identify the origins of groundwater at different locations in the alluvium and along the course of streams in the Lockyer Valley (Queensland, Australia), a catchment impacted by a severe drought (‘Millennium Drought’) from 1998 to 2009, followed by extensive flooding in 2011. We also demonstrate how discharge from the sub-alluvial regional-scale volcanic and sedimentary bedrock influences the water balance and water quality of the alluvium and streams. The investigation of aquifer geometry via development of a three-dimensional geological model combined with an assessment of hydraulic data provided important insights on groundwater flow paths and helped to identify areas where bedrock aquifers interact with shallow alluvial aquifers and streams. Multivariate statistical techniques were then applied as an additional line of evidence to groundwater and surface water hydrochemical data from large historical datasets. This confirmed that most sub-catchments within the Lockyer Valley have distinct water chemistry patterns, which result from mixing of different water sources, including discharge from the sub-alluvial bedrock. Importantly, in addition to the observed spatial variability, time-series hydrochemical groundwater and surface water data further demonstrated that the hydraulic connection between alluvial aquifers, streams and sub-alluvial bedrock aquifers is temporally dynamic with very significant changes occurring at the transition from normal to drought conditions and following flooding, affecting both catchment water quality and water balances. <b>Citation:</b> M. Raiber, S. Lewis, D.I. Cendón, T. Cui, M.E. Cox, M. Gilfedder, D.W. Rassam, Significance of the connection between bedrock, alluvium and streams: A spatial and temporal hydrogeological and hydrogeochemical assessment from Queensland, Australia, <i>Journal of Hydrology</i>, Volume 569, 2019, ISSN 0022-1694, https://doi.org/10.1016/j.jhydrol.2018.12.020.
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document
eCat Id
120186
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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Keywords
- theme.ANZRC Fields of Research.rdf
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- EARTH SCIENCES
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- Lockyer Valley, Queensland
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- Groundwater-surface water interaction
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- Aquifer interaction
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- recharge
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- 3D geological modelling
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- Hydrochemistry
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- Bedrock
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- Published_External
Publication Date
2024-02-14T01:30:34
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completed
Purpose
This is a draft journal paper being developed as part of collaborative research efforts between GA and CSIRO, arising from work for the Bioregional Assessment Programme. The authors will submit this paper to a leading scientific journal for publication via the usual peer review journal article process.
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geoscientificInformation
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Journal of Hydrology Volume 569, February 2019 666-684
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Draft journal paper under development by co-authors in preparation for submission to scientific journal for review and acceptance.
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[-27.8172, -27.4083, 151.8256, 152.3749]
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