ANALYSIS OF SATELLITE RADAR FOR THE DETECTION AND MAPPING OF INUNDATION 
PATTERNS IN WETLAND AREAS 
A. K. Milne 
Office of Postgraduate Studies 
The University of New South Wales 
Sydney 2052 Australia 
Tel: 61 (02) 9385 2731, Fax: 61 (02) 9385 3733, 
Email: t.milne@unsw.edu.au 
RADARSAT data has been acquired over Kakadu National Park in Northern Australia during 1997-98. Within this park 
permanent, seasonal and intermittently flooded landscapes occur modulated by monsoonal conditions with the wet 
season occurring between December and March and the dry season, April to November. 
The ecosystems in these floodplain environments are complex, dynamic and resilient and often undergo changes in water 
depth ranging from being completely dry to being covered for three to four months by two to three metres of water. 
Vegetation communities include forest woodlands, scrub and heath, shrublands, sedge and grasslands, extensive floating 
macrophytes and submerged herblands, all of which relate and respond to the hydrologic regimes associated with either 
permanent water or seasonal inundation. 
Complimentary data sets including ERS-1 and 2, JERS-1; SIR-C, AIRSAR and TM along with RADARSAT are being 
investigated to map and study wetland environments within Kakadu Park. 
This paper presents the results of a comparative study in which the impact of wavelength, incidence angle, resolution and 
polarisation are evaluated in regard to the ability of satellite radar systems to detect the presence of water under trees and 
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to map the distribution and changing patterns of flooding in wetland environments. 
INTRODUCTION 
The potential of synthetic aperture radar (SAR) to map the 
distribution of wetlands, forests and woodlands and to 
monitor long term developments in these ecosystems, as 
well as to contribute to an understanding of global change, 
depends on the ability of science to unravel the 
relationships that exist between microwave backscatter, 
surface conditions and the physical characteristics of trees 
and forests. 
VEGETATION RESEARCH IN NORTHERN 
AUSTRALIA 
Four major research programs are currently being 
undertaken at the University of New South Wales in 
tropical Northern Australia incorporating the analysis of 
SIR-C/X SAR; ERS 1/2; RADARSAT and AIRSAR data 
along with Landsat TM and SPOT imagery. These are: 
e Investigating the Backscatter Properties and 
Dynamics of Australian Tree Types and Forests. 
e Monitoring Change in Coastal Wetlands, Forests 
and Woodlands in Northern Australia Using 
RADARSAT. 
e Characterisation of Vegetation and Land 
Surfaces on Intertidal Flats in Northern 
Australia using Radar. 
e Remotely Sensed Indicators of Habitat 
Heterogeneity and Biological Diversity: 
Kakadu World Heritage Region, Northern 
Australia. 
This paper deals primarily with using multi-temporal 
RADARSAT data to analyse and describe wetlands and 
examine the extent to seasonal changes can be captured by 
C-band radar. 
WETLAND INVESTIGATIONS 
The variable resolutions and swath widths of RADARSAT 
together with its repeat coverage capability provide a 
significant enhancement and new dimension to studies 
already in progress, namely, the ability to undertake 
regional mapping on a scale not previously possible and 
over several time periods. RADARSAT data is being 
used in this investigation to: 
(1) Map the extent of coastal wetlands across 
Northern Australia based on wet season/dry 
season imagery. 
(2) Monitor seasonal changes in the temporal and 
spatial patterns of inundation in selected river 
basins in order to delineate freshwater from tidal 
wetlands areas. 
(3) Contribute to the structural characterisation of 
vegetation types found in the Alligator Rivers 
Region catchment. 
(4) Monitor and assess changes. in wetland 
environments over time, including wetland loss 
and degradation as well as the extent and 
success of wetland conservation practices. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 
PDO as 2A di 3m Rows usos; ME