Abstract
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The coastal zone comprises a series of landforms and ecosystems that extend either
side of the shoreline, the intersection of land and sea. Coastal systems are highly
dynamic, their morphology evolving at a range of time scales in response to the processes
acting upon them. Whereas cliffs are generally resistant and change only over long time
scales, with evidence of substantial changes over a geological time scale in response to
adjustments of sea level, sandy shorelines are much more responsive at instantaneous and
event time scales, influenced by wave energy and antecedent conditions. Particularly
relevant in terms of coastal management are engineering time scales of decades at which
human interactions exert subtle influences with need for planning and policies that are
commensurate with natural trajectories of change. Complex coasts such as estuaries and
deltas also respond to gradients in wave, tide and river processes, undergoing adjustments
such as the switching of delta distributaries. The morphology (state) of the coast changes
in response to perturbations, particularly extreme events such as storms, but also
thresholds within the system (as when a cliff oversteepens and falls, or a delta
distributary lengthens and then switches). As anthropogenic modification of climate and
sea level occurs at a global scale, the human factor increasingly needs to be given
prominence in coastal geomorphology.
The geospatial portrayal of coasts is not straightforward. Traditional GIS data
models and structures have been designed for land-based applications. The
multidimensionality and dynamic characteristics of coastal systems make it challenging
to transfer these concepts across the coastal zone. Even the conceptualization and
selection of an appropriate shoreline can be difficult, in addition to the implementation of
an appropriate data structure which suits the continual adjustment of iconic coastal
systems. Whereas coastal terrain represents a fundamental dataset, data accuracy and
availability for the coast vary from terrestrial, through intertidal to subtidal environments,
and the complexities resulting from different datums compound the compilation of a seamless coastal terrain model. A series of sophisticated remote sensing techniques, such
as satellite imagery and airborne laser altimetry surveying, provide a source of
information for advanced spatial analysis of landforms and the recognition of habitats
within them, which can then be incorporated into coastal geodatabases. New techniques
in data portrayal, such as 3D visualization and animations, help bridge the gap between
science and decision-makers, and provide additional tools such as scenario-building that
can provide a basis for planning for a future that is uncertain, where identifiable hazards
such as episodic storms and shoreline protection may be exacerbated by less foreseeable
impacts associated with climate change and increasing population pressure.