Digital Earth Australia
Through a joint effort by Geoscience Australia and the Terrestrial Environment Research Network (TERN), annual 25 m spatial resolution maps of mangrove extent by canopy cover type (open woodland, open and closed) have been generated annually (from 1986-2016) and at a national (Australia-wide) level using dense time-series of Landsat sensor data held within Digital Earth Australia (DEA). The potential area that mangroves occupied over this period was established as the union of mangrove maps generated for 1996, 2007-2010 and 2015/16 through the Japanese Aerospace Exploration Agency (JAXA) Global Mangrove Watch (GMW). Within this area, the green vegetation fractional cover (GVpc) was retrieved from each available cloud-masked Landsat scene through linear spectral unmixing. The 10th percentile (GVpc10) was then determined for each calendar year by comparing these data in a time-series and the percentage Planimetric Canopy Cover (PCC%) for each Landsat pixel was estimated using a relationship between GVpc10 and LiDAR-derived PCC% (< 1 m resolution and based on LiDAR acquisitions from all states supporting mangroves, excluding Victoria).
Generation of the maps of mangrove extent and cover for Australia was facilitated by the data storage and processing capability available within Geoscience Australia's DEA and the approach utilised the fractional cover unmixing algorithm developed by the Joint Remote Sensing Research Program. This world leading resource provides considerable opportunity for national and international scientists, bodies (e.g., the United Nations), governments, land managers and the public to better understand the changing state of mangroves along the entire coast of Australia, particularly in response to sea level fluctuations and also tropical storms. Processing was undertaken within the framework of the Open Data Cube, which facilitates transferability of processing of satellite sensor data to the global community.
The maps of mangrove extent by cover type are provided by Geoscience Australia for all years and can be viewed and compared here:
Lymburner, L., Bunting, P., Lucas, R., Scarth, P., Alam, I., Phillips, C., Ticehurst, C. and Held, A. (2018). Mapping the multi-decadal mangrove dynamics of the Australian coastline. Remote Sensing of Environment (in review).
The research was undertaken in collaboration with Aberystwyth University's Earth Observation and Ecosystem Dynamics Research Group (EOED) and the University of New South Wales' (UNSW) School of Biological and Environmental Sciences (BEES)