Australian Digital Elevation Model Data Products

The Australian Digital Elevation Model (DEM) has been developed using the CRES
package ANUDEM. It is available at a continental scale at two spatial
resolutions - 1/20th degree and 1/40th degree. The DEM is also available at a
finer resolution (1/60th degree or 1 minute) for individual states.

The First DEM of Australia

The first DEM of Australia at a resolution of 1/10th degree (approximately 10
km) was calculated by Moore and Simpson (1982) using the minimum curvature
interpolation procedure of Briggs (1974) applied to a point elevation data set
containing about 320 000 points . These data were measured during a
continent-wide gravity survey conducted by the Bureau of Mineral Resources
(Anfiloff et al., 1976). Though detailed enough to detect significant
geological structures (Harrington et al., 1982), this DEM suffered from a
number of acknowledged limitations from the point of view of hydrological
analysis. Extreme heights were not well represented and the 1/10th degree
resolution could only support quite generalized drainage structures. The data
were also known to contain a number of errors.

The New DEM of Australia

The new 1/40th degree DEM of Australia has been calculated by the elevation
specific gridding technique described by Hutchinson (1988, 1989). This
technique ensures that the DEM has a connected drainage structure by
automatically removing spurious pits or sinks. The DEM also incorporates the
stream line network digitized from the 1:2.5 M scale map of Australia (Division
of National Mapping, 1984). A summary of the point elevation and stream line
data used is given in Table I. A total of about 580 000 elevation data points
were used, of which 400 000 were provided by the Bureau of Mineral Resources.
These included the 320 000 elevation points used by Moore and Simpson (1982).
The inclusion of the trigonometric data points ensured that most of the
principal peaks were incorporated into the DEM. Additional point and stream
line data were digitized from 1:250 000 scale topographic maps to provide more
detail and to remove remaining drainage anomalies, particularly in areas with
complex terrain. Sink data points were also digitized to prevent drainage
clearance of genuine depressions, although the drainage enforcement algorithm
is generally sufficiently sensitive to ensure that genuine depressions are not
cleared, whether or not they have been identified as such in the data
(Hutchinson, 1989).

[Summary provided by the Australian National University.]