Using airborne electromagnetics (AEM) to map losing and gaining reaches along the River Murray between Lindsay and Walpolla Islands, Murray Basin, SE Australia  

Authors / CoAuthors

Tan, K.P. | Halas, L. | Lawrie, K.C. | Apps, H.E.

Abstract

The Murray River is known to display great complexity in surface-groundwater interactions along its course, with 'gaining' sections of the river identified as sites of regional saline groundwater system discharges to the river and the adjacent floodplain. In the Lindsay - Walpolla reach of the River Murray, an airborne electromagnetics (AEM) survey acquired in a 20 km 'wide swath along the river, has enabled key elements of the hydrogeological system to be mapped. Electrical geophysical methods (such as AEM) are able to map the extent and thickness of lateral bank infiltration ('flush') zones, due to the contrast between fresh water leaking from the river and brackish to saline groundwater in adjacent sediments. This study found flush zones in the study area to be present relatively continuously to depths of 5-10m in zones of varying width (200m to <4 km). Development of flush zones to greater depths (up to 25 m) is restricted. The River is interpreted as a weakly losing reach of the river system (at the time of the AEM survey). The most extensive flush zones in the study area are associated with locks, weirs and irrigation districts. Salt mobilisation associated with the flush zones at weir pools may be an issue in terms of salt load delivery to the River Murray and floodplain. Reaches of the river where the flush zones are absent and /or significantly constricted, and similar zones in tributary creeks in the adjacent floodplain, are at higher risk of saline groundwater inflows.

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nonGeographicDataset

eCat Id

73661

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Keywords

• GA PublicationAbstract

( Theme )

• groundwater

( Theme )

• hydrogeology

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2012-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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