High and low tide characterisation of the Australian coastline

Dr Stephen  Sagar1, Dr Leo Lymburner1, Dr Claire Phillips1, Mr Biswajit Bala1, Dr Dale Robert1

1Geoscience Australia, Symonston, Australia

Abstract

Intertidal zones are dynamic, unique and extreme environments due to the combined effects of the tide, exposure and weather. As a result, the ecosystems they host are dynamic and unique, ranging from migratory bird habitat to larval fish nurseries and mangrove wetlands. For the essential functions that these environments offer, they cover an extremely small area of continental landmass. Furthermore, these environments are notoriously difficult to survey and clearly characterise using remote sensing, mainly due to the varying coverage of water throughout the tidal cycle.

High and low tide image geomedian composites of the Australian coastline have been produced from the Landsat imagery archive, stored and managed within the Digital Earth Australia (DEA). Modelled tide heights were attributed to all coastal images in the archive, enabling the generation of composite images from archival subsets, based on Landsat images acquired between 2000 and 2017 and sorted into the upper or lower 20 percent of the observed tide range.

The result is two highly detailed, clear and cloud free composite images of the Australian coastline, at a resolution of 25 m2 for both high and low tide and which will be freely accessible online. This tidally tagged archive of satellite imagery can be further used to investigate coastal and event based change by varying the temporal domain and restricting tide-based variability in the subsets used for composite generation.

Biography

Stephen Sagar is the Marine Remote Sensing Project Leader within the Digital Earth Australia (DEA) program at Geoscience Australia. His research interests include the development of products from time series earth observation data, for understanding the dynamics of the coastal and marine environment.


Leo Lymburner has been working in the field of remote sensing since 1998.  He gained his PhD in remote sensing of riparian vegetation in 2006 and has been working at Geoscience Australia on land cover mapping and data cube applications since 2008.  Leo a member of the Landsat Science Team.

About the Association

The Australian Coastal Society (ACS) was initiated at the Coast to Coast Conference in Tasmania in 2004. The idea was floated as a means for those interested in coastal matters to communicate between conferences and where possible take resolutions of the conference to appropriate levels of government.

The idea was discussed further at the Coast to Coast Conference in Melbourne in 2006 and it was agreed that Bruce Thom develop a constitution of a company limited by guarantee that would operate on a national basis.

This plan was accomplished and in 2008 at the Coast to Coast Conference in Darwin the constitution was ratified and an Executive appointed. The company received charitable status in 2011.

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