Potential of GIS in Coastal Boundaries Detection and Pitfalls in Representing the Coast as a Boundary

Maria Raffaella Lamacchia (1) , Darius Bartlett (2)

(1) SAT Department, Mediterranean University of Reggio Calabria (IT)
(2) Geography Department, University College of Cork (IE)

"Boundary" and "coast" are terms linked by a twofold relationship: on the one hand, the coastal zone is unanimously defined as the boundary area between land, sea and air (Carter 1988); on the other, the issue of coastal boundaries definition is addressed by the international literature as one of the most thorny subjects implied by ICZM theories and practices (Cicin-Sain 1993). The definition of coastal boundaries is a tricky task, since it implies the definition of the boundaries of the boundary itself.
A review of the main definitions set up by scientists (geomorphologists, oceanographers, biologists, ecologists, economists etc), pratictioners (politicians, administrators, entrepreneurs, etc.) and local comunities indicates use of a wide range of boundary types to delimit and manage the coastal zone. These include geomorphologic boundaries, hydrogeological boundaries, biological boundaries, ecological boundaries, legal boundaries, utilitarian boundaries, perception boundaries, etc. Upon closer examination of these, it is possible to confirm Carter's (1988) view that all these definitions move from a common idea: the coast is that boundary region between sea and land made up of that portion of land considerably affected by proximity to the sea, and that part of ocean considerably affected by its proximity to the land.
The illustrated twofold relationship connecting the words 'coast' and 'boundary' in turn leads towards further dual relationships between nature and humanity, and between coastal boundaries and GIS applications. GIS tools are successfully applied by practitioners in terrestrial and maritime boundary delineation, for example where they are used to locate legal and conventional boundaries established by humans, such as the limits of maritime zones defined by means of geometrical rules according to the United Nation Convention on the Law Of the Sea - UNCLOS (i.e.: the GIS-based Global Maritime Boundaries Database set up and distributed by Verdian MRJ Technology Solutions), and also where GIS are employed by scientists for detecting the limits of the natural elements of the marine and territorial domain, such us ecosystems boundaries, catchment basins etc. At the same time, GIS databases and tools show enormous limits in facing the boundary nature and the associated fuzziness of coastal systems.
A number of comparatively recent theories such as Fuzzy Logic, Fractal Theory, and Boundary Objects, along with emerging disciplines such as Landscape Ecology, etc., support us in dealing with the boundary nature of coasts: Fuzzy Logic theories (Zadeh 1965, 1987) help us in grasping the structural indeterminateness of boundaries between spacial regions; Boundary Objects and the related concept of Trading Zones (Chrisman, 1999) represent attempts at circumventing the problems of defining objects that are inherently subject to multiple interpretations by "agreeing to differ"; Fractal theories (Mandelbrot 1983), help us in assessing boundaries length and shape, and in understanding their spatial and temporal dependence; while Landscape Ecology considerations on environmental boundaries (Forman 1995, Forman and Moore 1992) allow us to reflect on structure and functions (habitat, conduit, filter/barrier, source and sink) of the boundaries between landscapes elements.
The deriving conceptual model of the coast as a boundary is not easy to implement in current geographical information systems, since these are designed to deal almost exclusively with static, well-defined 'objects', exactly located in space with properly defined attributes (Burrough and Frank 1996). At present the coast is generally represented within GIS through one-dimentional or two dimentional datasets, and in few experimental cases it is represented taking into consideration its third (height) and fourth (temporal change) dimension (Bartlett 1993). Even in these latter cases, however, coastal representations are forced into the classic, crisp mode of conventional information theory and traditional cartographic methods, since most GIS seems theoretically inadequate to deal with objects with poorly defined boundaries, such as the coast and its elements.
The current paper examines these issues from the specific perspective of the territorial and regional planning professional, and considers the implications of coastal boundary delimitation for the elaboration, communication and implementation of international coastal zone management plans. To illustrate the problems raised, examples are drawn from case studies of the coasts of Bari on the Adriatic coast of sout-east Italy, and County Cork on the south-west coast of Ireland.