Geoscience Australia DEM 9 Second Australia

Overview

• Grid of ground level elevation points covering the whole of Australia
• Grid spacing of 9 seconds in longitude and latitude (approximately 250 metres) in the GDA94 coordinate system
• Includes topographic information such as point elevation data, elevation contours, stream lines & cliff lines

GEODATA 9 Second Digital Elevation Model (DEM-9S) is a grid of ground level elevation points covering the whole of Australia with a grid spacing of 9 seconds in longitude and latitude (approximately 250 metres) in the GDA94 coordinate system.

The source data includes revised versions of elevation points, streamlines, cliff lines and water bodies as well as trigonometric points from the National Geodetic Database and additional elevation and sink point data digitised by the Fenner School from 1:100 000 scale source material.

GEODATA 9 Second Flow Direction Grid (D8-9S) is a corresponding grid (included on the DVD), describing the principal directions of surface drainage across the whole of Australia. This grid was calculated by the ANUDEM procedure as it derived the DEM-9S. It incorporates the data streamline structure and describes the drainage structure continent-wide. It can be used to delineate streamlines and associated catchment boundaries for the DEM-9S. This is particularly useful in low relief areas where drainage structure is not reliably defined by the DEM-9S elevations alone.

This product can be used for applications requiring accurate representation of absolute elevation values. The elevation of source data high points (hills or mountains) is well represented in Version 3. The 1:250 000 source scale of the elevation grid makes the product useful for national, State-wide and regional applications.

DEM-9 Second is a model of the terrain in which each data point represents the approximate elevation at the centre of each 9 second by 9 second cell. The density of source data points used to create the DEM, and its horizontal resolution, warrant that the DEM be considered to have a scale of approximately 1:250 000. This makes the DEM useful for national, statewide and regional applications, particularly those applications that depend on an accurate representation of surface drainage and catchment structure.