The Evolution of East Coast Australian Estuaries and Implications for Geotechnical Investigation

Daniel Bishop

The heavily developed and populated east coast of Australia comprises numerous estuary systems, evolved within deeply incised valleys east of the Great Dividing Range. Sediment sequences that fill these estuaries are complex and pose many challenges to engineering development. Not least of these challenges is predicting the distribution and behaviour of the thick deposits of soft estuarine clays that fill these valleys.

Unfortunately there appears to be a significant gap between current understanding of coastal evolution in geoscience research fields and simplified concepts typically utilised by the local geotechnical profession. A significant part of the problem has been the absence of any active research to translate and apply up-to-date geological concepts into the realm of geotechnical investigation.

A conceptual framework will be presented that integrates recent developments in coastal estuary models with the concepts of sequence stratigraphy and morphodynamics. Influences of past sea level change and climate change will be discussed. Application of the framework to geotechnical investigations in estuaries will be described with reference to recent work conducted in the Richmond River. Some key geotechnical outcomes arising from this work will be highlighted.

The ideas presented in this lecture have been developed during research into the distribution and behaviour of soft clays in the Richmond River Estuary conducted at the University of Newcastle and in cooperation with the NSW RTA.

About the speaker

Daniel Bishop Senior Engineering Geologist, Pells Sullivan Meynink Pty Ltd

Daniel Bishop is a Senior Engineering Geologist with Pells Sullivan Meynink Pty Ltd in Sydney. He holds a First Class Honours degree in Geology and is currently completing a Doctor of Philosophy degree at the Centre for Geotechnical and Materials Modelling, University of Newcastle. He is a member of the Australian Geomechanics Society.

Daniel has gained research and field geology experience investigating crustal scale deformation zones in the Archean greenstone belts of Western Australia, and Precambrian tectonic zones in Madagasca. A long term interest in geomechanics led to the research opportunity at Newcastle University. While at Newcastle Daniel assisted in teaching the Engineering Geology course and played an active role in the Newcastle chapter of the AGS.

Over the last 15 months Daniel has been working on a number open cut pit design projects for copper porphyry deposits in Indonesia and the Philippines. He is also currently juggling the completion of his PhD thesis while embarking into the realms of parenthood!

Engineers Australia members participating in AGS technical sessions can record attendance on their personal CPD logs. Members should refer to Engineers Australia CPD policy for details on CPD types, requirements and auditing guidelines.