Authors / CoAuthors
Halas, L. | Magee, J. | Lawrie, K. | Pain, C. | Clarke, J.
Abstract
Australia's floodplain environments are typically low-relief landscapes that can exhibit a high degree of (subtle) landscape complexity, high variability in permeability characteristics, and hence highly variable recharge potential. In the Broken Hill Managed Aquifer Recharge project, geomorphic maps of a large area (7,500 km2) of the Darling River floodplain near Menindee N.S.W. were produced in two stages. Initially, broad-scale mapping to identify high order landscape features was carried out using Google Earth. These maps were used for project planning and initial assessments of drilling locations. A second phase of higher resolution mapping utilised a LiDAR DEM, which was levelled using trend surfaces to eliminate regional slope (~20m). An ArcGIS interactive contour tool was then used to identify specific breaks in elevation associated with landform features. Multivariate image analysis of elevation, high resolution SPOT and Landsat-derived wetness further enhanced the contrast between geomorphic elements to confirm mapping boundaries. While specific landforms can be characterised by particular surface materials, these sediments can vary within a single geomorphic feature. Consequently, SPOT multispectral satellite imagery was used to identify surface materials using principal component analysis and unsupervised classification. This approach generated 20 classes; each assigned a preliminary cover/landform attribute using SPOT imagery. Field data (surface and borehole sample, and observations at shallow pits) were used to refine the classification approach. Interactive mapping using a de-trended DEM provided a rapid, effective and accurate alternative to time consuming manual landform digitisation. Integration of geomorphic and surface-materials maps helped identify potential natural infiltration sites and assess options for managed aquifer recharge (MAR) including potential dune and basin infiltration.. The high-resolution geomorphic and surface-materials maps, validated by shallow augering, pits and drilling, were also essential for the interpretation of near-surface layers in a regional airborne electromagnetics (AEM) survey. The geomorphic maps also provided a key input layer to the assessment of groundwater dependent vegetation and overall MAR assessments.
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nonGeographicDataset
eCat Id
75754
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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2601
Australia
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- External PublicationAbstract
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Geology
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- Published_Internal
Publication Date
2013-01-01T00:00:00
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geoscientificInformation
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Abstract prepared for submission to the International Association of Hydrogeologists (IAH).
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