Professor Michael Hutchinson

Understanding how Australia’s precious water drains across the surface of the continent will be dramatically improved thanks to a new national Digital Elevation Model (DEM). The new data will contribute significantly to water accounting, modelling the impacts of climate change projections and a broad range of other applications.

Researchers from The Australian National University (ANU) and Geoscience Australia have just finalised a new version of their GEODATA 9 Second Digital Elevation Model (DEM-9S). Version 3 marks the culmination of more than a decade of work, providing a grid of ground-level elevation points covering the whole of Australia, with a grid spacing of nine seconds in longitude and latitude, or roughly every 250 metres.

Professor Michael Hutchinson from ANU says “the core data underpinning the new database include revised versions of elevation points, streamlines, cliff lines and water-bodies; trigonometric points from the National Geodetic Database; and, additional elevation, streamline and sink point data digitised from source material. The procedure also incorporated major upgrades to the ANUDEM modelling software to improve the representation of streamlines, lakes, cliff lines and the coastline. While there are many locations where higher accuracy data are available, the new product provides the only nationally consistent data for modelling across the entire continent”.

The new database also includes a corresponding Flow Direction Grid (D8-9S), which describes the principal directions of surface drainage across the whole of Australia. It can be used to delineate streamlines and associated catchment boundaries. This is particularly useful in low-relief areas where drainage structure is not reliably defined by elevations alone. Phil Tickle from Geoscience Australia says “the new data shows that only around 50% of Australia’s drainage basins actually flow to the sea”.

This work is going to underpin the Australian Governments Water for the Future program and the Australian Water Resources Information System being developed by the Bureau of Meteorology. Work has already begun on the next generation of national DEM that will that will improve the resolution from 250m to less than 90m.