546 
SCANSAR data. Eight images annually will be 
calibrated, registered together and interrogated in 
an attempt to derive a map of the distribution of 
wetlands across Northern Australia. Comparison 
of wet and dry season images will also be 
undertaken in an attempt to try and distinguish 
between tidal and freshwater ^ wetland 
environments. 
Imagery from at least four contiguous swaths 
(depending on orbital paths) will be needed to map 
the full extent of wetlands across Northern 
Australia. 
Regional mapping of the wetlands of Northern 
Australia will be carried out in all three years of 
the project. 
Detailed mapping of the Alligator Rivers Region 
wetland environments using RADARSAT data. 
Hydrologic, geomorphic and ecological field and 
reference data is being acquired after the end of 
the wet season to coincide with the recession of 
floodwaters. Successive stages in the drying of the 
floodplain will be monitored and the changing 
environmental conditions identified and compared 
to changes in the backscatter return recorded on 
successive images. 
Closely related to (2) will be the determination of 
specific wetland processes associated with: 
(a) hydrology - monitoring the seasonal 
pattern of floodwater recession; 
measurement of sediment and biological 
loads. 
(b) geomorphic changes - examining the 
interface between freshwater and tidal 
estuary areas over a 6-9 month period to 
determine if headwater extension of 
saltwater streams is occurring into 
freshwater floodplains. 
(c) characterisation of vegetation found 
within the 
(1) tidal mangroves 
(ii) coastal salt marshes and mud flats 
(iii) seasonally inundated floodplain, 
lakes and waterholes 
(iv) | macrophytic distributions 
(v) adjacent abutting 
woodlands and forests 
upland 
Regional mapping and the monitoring of 
hydrologic, geomorphic and ecological patterns 
and processes will be repeated and extended in 
1999. The timing and sequence of RADARSAT 
data requests will be adjusted based on the spatial 
and temporal patterns observed in the landscape in 
1998. 
Also, in 1998, the research will focus on the 
characterisation, field sampling and the 
measurement of biomass in selected vegetation 
habitats as well as determining changes in the 
pattern of inundation and recession of floodwaters. 
S: A GIS relational database is being established at 
the Environmental Research Institute of the 
Supervising Scientist (ERISS) in Kakadu National 
Park to incorporate the results of the ongoing 
hydrological, geomorphic, ecological ^ and 
biochemical studies related to the management of 
wetlands. Image processing and analysis of 
RADARSAT will be undertaken at the Centre for 
Remote Sensing and GIS at the University of New 
south Wales and transferred to the ERISS 
database. 
6. A regional map of the wetlands of Northern 
Australia will be published incorporating 
RADARSAT data and planimetric information 
derived from other sources. 
Sequential maps of floodplain inundation levels 
for the Alligator Rivers Region for 1998 and 1999 
will be assessed and absolute and relative changes 
in the hydrologic, geomorphic and ecological 
characteristics of the wetland environment 
examined and described. Strategies for assessing 
and verifying longer term changes in the wetland 
environment will be developed. 
The methodology developed for producing the 
sequential mapping of individual wetland 
catchments in the Alligator Rivers Region will be 
applied to the Ord River drainage basin in Western 
Australia and other ecological catchments across 
Northern Australia. 
RESULTS TO DATE 
The results of the analysis of the first year of 
RADARSAT data for examining and describing the 
vegetation response associated with the wet-dry seasonal 
conditions will be presented at this conference, however, 
significant results have been made in several related 
studies. The first empirically based statistical 
relationships between radar backscatter and = field 
measurements of selected tree parameters in tropical 
Australian forests that demonstrate multi-polarimetric 
SAR responds to vegetation structure (eg. total biomass, 
leaf-area index, branch surface/volume ratio etc.) in 
predictable ways have been demonstrated (Imhoff, et al, 
1997). 
These results show radar sensitivity to floristically 
induced structural changes across the Kakadu study site , 
indicating that given appropriate algorithms, 
physiognomic classifications of trees and community 
typology may be possible with radar. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998