Authors / CoAuthors
Gow, L. | Lymburner, L. | Halas, L. | McIntyre, A. | Magee, J.
Abstract
A novel methodology has been developed to assess potential impacts of managed aquifer recharge (MAR) and/or groundwater extraction on groundwater dependent ecosystems (GDEs) in the Darling River floodplain. Potential negative impacts on GDEs include: (1) lowering of watertables in response to groundwater extraction, with the potential for enhanced leakage from lakes and rivers; and (2) raising of the watertables as a result of enhanced recharge. The latter has the potential to lead to saturation and/or salinisation of root zones through mobilisation of salts stored in the unsaturated zone. Depending on the magnitude of watertable fluctuations, type of vegetation, and degree of groundwater dependence, this can have significant implications for vegetation function. In this study, time-series Landsat data were used to identify groundwater dependent vegetation (GDV). Field-validated GDV maps were integrated with 3D sub-surface hydrogeological, hydrogeochemical and hydrodynamic data to characterise the hydrogeological system and understand controls on GDV distribution and condition. Particular attention was paid to the distribution and integrity of near-surface aquitards and identifying potential sites for inter-aquifer leakage and enhanced recharge. This paper reports on two sites: Jimargil and Lake Menindee. GDV at both sites (e.g. Eucalyptus camaldulensis (River Red Gum) and E.largiflorens (Black Box)), depends largely on groundwater in shallow unconfined aquifers. At the Lake Menindee site, remnant woody vegetation is concentrated along lake fringes, while the Jimargil site includes a narrow strip of riparian vegetation associated with the Darling River. At the Lake Menindee site there is a high degree of connectivity between the lake, shallow watertable, and target aquifer. Current management of lake levels impacts on GDVs at this site, and negative impacts are likely to be compounded by groundwater extraction and/or MAR. In contrast, connectivity between the shallow unconfined aquifer (and the Darling River) that sustain GDV communities at Jimargil, and the semi-confined target aquifer, is localised along faults and gaps in the intervening aquitards. Groundwater extraction and/or MAR in the deeper aquifer at the site would have minimal impacts on riparian and floodplain GDV.
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nonGeographicDataset
eCat Id
75765
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- External PublicationAbstract
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Geology
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2013-01-01T00:00:00
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Abstract prepared for submission to the International Association of Hydrogeologists (IAH).
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