GEOMORPHOLOGY REPORT - CRC LEME

The SRTM was used as to provide the base DEM where other data was not available. At a
scale of 1:25,000 the vertical and spatial resolution is too low while the noise level is too high
in the Shuttle Radar DEM for mapping purposes, and hence, has been used for infill only.
High resolution (2 and 5 m) LIDAR DEMs were used for the primary interpretation
(Appendix 3). The Lindsay and Wallpolla LIDAR data were supplied by SunRISE 21 in xyz
format (134 & 74 files respectively). These were imported and gridded in Intrepid and then
exported to ERMapper format as 1m and 5m grids. The LIDAR data on the eastern part of the
project area were supplied by MDBC. The tiles, at 2m resolution, were mosaiced together in
Arc Info. There are two DEMs derived from digitised contour maps; one at 10 m resolution
and the other at 20 m resolution (Figure ). The 20 m DEM data was provided by ACRES in
ERMapper format. The 10m DEM data was supplied as 175 xyz ascii files by SunRISE 21 on
behalf of the Mallee CMA. The ascii files were imported into Intrepid, saved in ERMapper
format, and clipped to the project area. The 10m grid has a stated vertical accuracy of 2m
AHD. These were used as infill when other data were not available.
Figure 5. Coverage of digital elevation model types.
4.2.3 Gamma-ray data
Airborne ternary gamma-ray images were used to supplement areas with poor coverage of
high resolution DEM (Appendix 4). This is effective because the materials of the terrace
formed by the Rufus Formation (Gill 1973) are distinct from those of the active floodplain on
ternary gamma-ray images, as described in more detail below. The distribution of this
material was used when absence of LIDAR coverage precluded mapping of the position of
terraces by more accurate means.
4.3 Satellite image Processing
The ASTER level 1B scenes were supplied by ACRES in .hdf format. They were corrected
for crosstalk (caused by signal leakage from band 4 into adjacent bands 5 and 9) and imported
into ERMapper. Importing was carried out in three steps with bands of similar resolution. The
VNIR bands 1-3 at 15m resolution, SWIR (shortwave infrared radiation) bands 5 – 9 at 30m
resolution and TIR (thermal infrared radiation) bands 10 – 14 at 90m resolution. All bands
were rotated, calibrated for radiance, by rescaling digital values to observed top of
atmosphere radiance values, and had dark pixel corrections. Resultant ERMapper datasets
were displayed as composite RGB images.
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