The definition
of these particular survey lines is important in terms of environmental
management and legislation (e.g. native title). Airborne SAR is
well suited in delineating the watermarks, due to its relatively
high resolution and speed of data capture (only a small window of
time exists in which the tide is suitable for image acquisition).
Much of the Northern Territory coastline is subject to significant
tidal regimes. Tidal variations in excess of seven (7) metres is
not uncommon.
This variation in the z-axis can translate to large tracts of land
in the x-y plane.
This currently loosely or in most cases undefined zone is often
the subject of environmental management issues and ownership dispute.
Having accurate map data of this nature is very important in the
decision-making process influencing these issues.
GecOz have utilized airborne radar imagery to acquire such data
and produce the watermark lines (specifically the mean low water
mark) for parts of the Northern Territory coastline.
The images below show the results of mapping the watermark from
timely acquired airborne radar imagery.
Fig. 1: Radar image of a section of the NT coastline
Fig. 2: Watermark derived from in-house image classification techniques
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