Analysis of sedimentary structures of the outer shelf and upper continental slope, NW Australia - Information for pipeline design

Piers Larcombe, Steve Buchan, Gareth Edwards

Research output: Contribution to conferenceConference presentation/ephemerapeer-review

Abstract

This paper: i) outlines selected aspects of the sediment transport regimes, net directions and driving processes on the northern outer shelf and upper continental slope of NW Australia, and; ii) demonstrates that pipeline design and engineering can benefit from an understanding of internal sedimentary structures in sediment cores. Along a 150 km long proposed pipeline route, in depths of 170-270 m, a suite of physical data were collected, including 12 months of near-bed currents and a suite of undisturbed Senkenberg cores that were analysed for their internal sedimentary structures and age. Work was supported by a range of existing geophysical survey data and underwater images of the seabed. The ages of the sediments were used to: i) inform assessments of the contribution of modern sediment sources, and ii) help identify which parts of the route were a) accreting sediment b) transferring it across the bed, or c) being eroded. The net direction of bed sediment transport at each point was interpreted from the array of sedimentary bedforms and their morphological characteristics. Preserved internal sedimentary structures indicated the formative sedimentary bedforms and the likely associated past flows. Bedforms evident on geophysical records were interpreted similarly. Some surface bedforms and internal structures are consistent with sustained flows of higher magnitude than those measured. The work delivered improved assessments of relative sedimentary 'risk' for various sections of the pipeline route, based on their observed and inferred physical characteristics, informing pipeline design and engineering.

Original languageEnglish
Pages739-745
Number of pages7
Publication statusPublished - 2019
Externally publishedYes
EventAustralasian Coasts and Ports 2019 Conference - Hobart, Australia
Duration: 10 Sept 201913 Sept 2019

Conference

ConferenceAustralasian Coasts and Ports 2019 Conference
Country/TerritoryAustralia
CityHobart
Period10/09/1913/09/19

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