Dr Brendan Brooke1, Dr Claire Phillips1, Dr Leo Lymburner1
1Geoscience Australia, Canberra, Australia
We assessed the utility of the Australian Landsat archive in the Digital Earth Australia (DEA) analysis platform for mapping estuarine landforms and habitats, and changes over time in their distribution and extent, in areas known to be important for threatened and migratory species.
Seven estuaries were examined, Darwin Harbour and the Keep, Daly, Roper, Macarthur, Flinders and Gilbert River estuaries, as part of a scoping project in the National Environmental Science Program’s Marine Biodiversity Hub. The estuaries were selected because they are known to provide biologically important areas for the species of interest, especially shorebirds, and including elasmobranchs (e.g. sawfish, river sharks), and dugong. Detecting habitat change was enabled using the long (1987-2017) and dense (repeat observations at least once every two weeks) Landsat time series held in the DEA.
The results clearly depict the dynamic nature of some estuaries, including large-scale rapid shoreline change, with tidal flat extension, island growth and mangrove expansion (e.g. Keep River and Gilbert River estuaries); gradual long-term expansion of mangrove (Flinders River and McArthur River estuaries); and estuaries with areas that have experienced rapid recent die back of mangrove (Roper River and Flinders estuaries).
This information is important for the management of key species and decisions around coastal developments. With Landsat and new satellite data streams (e.g. Sentinal 2) continually being added to the DEA, this time-series analysis approach could be developed into an effective habitat extent and condition monitoring tool for northern Australia. A key next step in this approach is to utilise ground-validation data to enable these habitats to be robustly classified and quantified using the Landsat archive.
Brendan is a Principal Scientist in the National Earth and Marine Observations Branch of Geoscience Australia. He has extensive experience leading and managing science teams investigating coastal and marine geology, geomorphology and habitats.