Vertical Datum Transformations across the Australian Littoral Zone

摘要

There is a growing demand in Australia for better information to assess the risks associated with sea-level rise and coastal inundation. Seamless elevation data across the littoral zone is an essential requirement for the assessment of coastal risks and the development of adaptation and mitigation strategies. Seamless coastal data products require the integration of topographic data with offshore bathymetric data. A prerequisite for the integration process is that the respective elevation data sets be related to the same vertical datum. This article discusses the development of a vertical datum transformation approach to facilitate the creation of seamless elevation data sets across the Australian littoral zone, with a focus on the challenges unique to Australia. Review of international projects, research into the relevant concepts, and an investigation of the data sets available in Australia led to the adoption of an ellipsoid-based transformation approach. Mean sea-level heights related to the ellipsoid and derived from coastal tide gauges were used to enhance a satellite altimetry derived mean sea surface. Other tidal datums were modelled through hydrodynamic modelling, and the Australian Height Datum was achieved via Australia's current geoid model: AUSGeoid09. Although a transformation procedure has been developed, the current status and availability of Australian tide gauge data prevent the production of a suitably accurate and reliable vertical datum transformation software tool that provides full coverage of the Australian coast. To produce such a tool, Australia requires the collation of existing tide gauge data and metadata, a repository to store that data, an ellipsoid height survey of all tide gauges, and a denser network of tide gauges.