Mangrove extent and cyclone damage, Hinchinbrook Island, QLD

This data set consists of a shapefile of mangrove extent around Hinchinbrook Island, Queensland, before and following Cyclone Yasi (February 2011).

Abstract or summary Cyclones are significant drivers of change within mangrove ecosystems with the extent of initial damage determined by storm severity, location and distribution (exposure), and influenced by species composition and structure (e.g., height). The long-term recovery of mangroves is often dependent upon hydrological regimes, as well as the frequency of storm events. On 3rd February 2011, Tropical Cyclone Yasi (Category 5) made landfall on the coast of north Queensland Australia with its path crossing the extensive mangroves within and surrounding Hinchinbrook Island National Park. Based on a combination of Landsat-derived Foliage Projective Cover (FPC), Queensland Globe aerial imagery and RapidEye imagery (Planetlabs, 2017), 16 % of the 13,795 ha of mangroves experienced severe wind throw during the storm.

The Queensland Herbarium Regional Ecosystem map was used to define the wetland region surrounding Hinchinbrook Island, which included mangroves and mudflats. Within this region, randomly sampled points were located and allocated to four land cover classes (surviving mangroves, dead mangroves, other vegetation (i.e. rainforest), and non-vegetated mudflats) with reference to 2009 and 2015 Landsat FPC and 2016 Queensland Globe imagery. A maximum likelihood algorithm was then applied to the 2014 RapidEye (visible, red edge and near infrared) spectral data based on statistics associated with 50% of the sample. The accuracy of the RapidEye classification was then determined using the remaining 50 %.

From the classification, 120 objects (typically < 10 ha in size) associated with and the temporal statistics for FPC and L-band HH and HV data were extracted subsequently (Fig4) for the four classes. These were then used to generate classifications for 2009 (prior to) and 2015 (following) Cyclone Yasi, with focus on identifying dead and live mangroves during these two periods. An accuracy assessment was conducted using randomly sampled points for surviving and dead mangroves. By comparing the maps, the area of and percentage mangrove loss was determined and summarised for Hinchinbrook Island (National Park zone), the island within Hinchinbrook Channel and the Queensland coastline.

References. Asbridge, E., Lucas, R.M., Rogers, K. and Accad, A., (2018). The extent of mangrove change and recovery following severe tropical Cyclone Yasi, Hinchinbrook Island, Queensland, Australia.

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