The coastal zone and its classification for geospatial analysis

C D Woodroffe; Javier X Leon

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 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 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. ©2010 Nova Science Publishers, Inc. All rights reserved.

The coastal zone and its classification for geospatial analysis

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