GEOMORPHOLOGY REPORT - CRC LEME

4 METHODOLOGY
4.1 Basic method and rationale
Mapping was done on transparent overlays at 1:25,000 scale and digitally converted into
electronic maps. The main presentation of the data was at 1:100,000 scale, mapping at
1:25,000 scale ensured that there was sufficient detail.
Landform mapping was carried out primarily by one of us (JC) using the LIDAR DEM where
possible. This was supplemented by lower resolution DEM data when the LIDAR was not
available, and compared against satellite imagery. DG carried out most of the mapping in the
areas with lower resolution. The landforms provided information on the spatial and
chronological relationships between different surface units.
Surface properties were mapped using ASTER by another one of us (VW), who also mapped
vegetation patterns from SPOT images. Gamma ray ternary radiometric images were used by
JC to differentiate surface material types where interpretation was difficult. Surface materials
provide information in the hydrologic properties, in particular recharge and salt load.
The polygons were field checked by JC and V Wong by vehicular traverses along various
tracks. Soil pits were dug and sampled, with field descriptions providing preliminary data on
soil properties (Appendix 6). These were followed by quantitative analyses (Appendix 7).
The maps were entered into the GIS by HA and JL, and the work was scientifically reviewed
by CP and KL.
4.2 Data Availability and Quality
4.2.1 Satellite imagery
The primary satellite images used to compile surface polygons were those from ASTER and
SPOT. LANDSAT images were used for comparison and infill, but were not normally
interpreted as SPOT and ASTER coverage was generally adequate for the project area.
ASTER interpretation is shown in Appendix 1), while SPOT interpretation is shown in
Appendix 2.
Three ASTER scenes (with 15m resolution) covered most of the Lindsay-Wallpolla and Lake
Victoria-Darling Anabranch area. The scenes, the only ones available, were acquired from
ACRES in GA. Two scenes were dated 14 Jan 2001 and one was dated 20 Nov 2000, with the
last scene unfortunately having a large section of cloud cover. The ASTER is displayed as a
composite RGB image using the visible and near infrared radiation (VNIR) bands 3, 2 and 1.
Four pan-sharpened pseudo natural colour SPOT scenes (with 2.5m resolution) dated 09 Jan
2005, 25 Feb 2005, 5 July 2005 and 24 Nov 2004 were also acquired from GA. Bands 3, 2
and 1 were displayed in a composite RGB image. Two Landsat-7 ETM ortho-corrected
images (30m resolution) used in the project were acquired on the 15 Mar 2002 and 4 April
2001.
4.2.2 Digital Elevation Models
DEM coverages are shown in Figure 5. Three coverages were used:
• LIDAR
• Elevation models fro digitised topographic maps
• SRTM data
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