Filling the ‘white ribbon’ – a multisource seamless digital elevation model for Lizard Island, northern Great Barrier Reef

Abstract

Hydrographers have traditionally referred to the nearshore area as the ‘white ribbon’ area due to the challenges associated with the collection of elevation data (elevation hereafter refers to both topography and bathymetry) in this highly dynamic transitional zone between terrestrial and marine environments. Accordingly, available information in this zone is typically characterized by a range of data sets from disparate sources. In this article, we propose a framework to fill the white ribbon area of a coral reef system by integrating multiple elevation data sets acquired by a suite of remote-sensing technologies into a seamless digital elevation model (DEM). A range of data sets are integrated, including field-collected global positioning system (GPS) elevation points, topographic and bathymetric light detecting and ranging (lidar), single and multibeam echosoundings, nautical charts, and bathymetry derived from optical remote-sensing imagery. The proposed framework ranks data reliability internally, thereby avoiding the requirements to quantify absolute error and results in a high-resolution, seamless product. Nested within this approach is an effective spatially explicit technique for improving the accuracy of bathymetry estimates derived empirically from optical satellite imagery through modelling the spatial structure of residuals. The approach was applied to data collected on and around Lizard Island in northern Australia. Collectively, the framework holds promise for filling the white ribbon zone in coastal areas characterized by similar data availability scenarios.

Acknowledgements

This research was supported by an ARC SuperScience Fellowship authored by the Global Change Institute and UQ's start-up grants (JL, MIS), Lizard Island Research Station Fellowship and a UOW University Research Committee ‘Near-Miss’ grant (SH). Bathymetric lidar was supplied by the Australian Hydrographic Office. The authors would like to thank the Lizard Island Research Station team and T. Baldock, C. Brown, D. Callaghan, V. Harwood, C. Roelfsema, and C. Woodroffe for field data collection and R. Borrego for atmospheric correction of the WV2 image.