CRC-SI Project 114: Reconciling Bathymetric Height Datums for Australian Coastal Data

Two incompatible height datums, the Australian Height Datum (AHD) for land and Chart Datum (CD) for sea, create difficulties for users joining coastal datasets. This report from the Australian Ocean Data Network presents a methodology to reconcile bathymetry datums by calculating uncertainty for Mean Sea Level observations. The research increases available MSL observations to aid in creating an ellipsoidal MSL surface with uncertainties, though methodologies for Highest and Lowest Astronomical Tide planes were not developed.

Use Cases

• Developing uncertainty models for coastal Mean Sea Level observations based on the described methodology.
• Creating seamless digital elevation models spanning the land/sea interface based on reconciled height datums.
• Improving nautical chart accuracy for under-keel clearance calculations based on the analysis of low water tidal datums.
• Assessing datum disparities when merging terrestrial and marine datasets for coastal management, as highlighted in the description.

Strengths

• Focuses on a specific, documented problem of datum disparity between terrestrial (AHD) and marine (CD/LAT) height references in Australia.
• Presents a concrete methodology for calculating uncertainty for short-span Mean Sea Level observations relative to a long-term reference epoch.
• Aims to increase the number of available MSL observations around the Australian coast, as stated in the description.

Limitations

• Methodologies for computing uncertainties of the Lowest Astronomical Tide (LAT) and Highest Astronomical Tide (HAT) tidal planes were not developed, as noted in the report.
• Column-level documentation is absent; field semantics must be inferred after download.
• Data format is HTML, which may require extraction and transformation for analytical use.

Provenance

Source

Australian Ocean Data Network

Collection Method

Research report from Co-operative Research Centre for Spatial Information (CRC-SI) Project 114.

Time Range

Report dated 2026-06-27.

Freshness

Last updated 2026-06-27 18:53:34.347080; freshness should be verified.

Geography

Australia, specifically its coastal regions.