1.2 Defining the coastal area
Defining the boundaries of a coastal area is of more than academic interest to coastal planners and managers. Governments often create administrative systems, or set out policies to guide decision-making, that operate within a
defined coastal policy area. The variety of ways in which such areas may be delineated in order to serve the purposes of particular policies are outlined in this section.
1.2.1 Scientific definitions of a coastal area
The coast is where land and ocean meet. If this line of meeting did not move, defining the coast would be easy-it would simply be a line on the map-but the natural processes that shape the coast are highly dynamic, varying in both space and time. Thus the line that joins land and ocean is constantly moving, with the rise and fall of tides and the passing of storms,
creating a region of interaction between land and sea.
There are parts of the coastal environment that clearly have strong interactions between land and ocean, including beaches, coastal marshes, mangroves and fringing coral reefs; other parts may be more distant from the immediate coast (inland or out to sea) but they nevertheless play an important role in shaping it. One of the most important of these is the
rivers that bring freshwater and sediment to the coastal environment. In this case, the inland limit to the coast is catchment boundaries that can be thousands of kilometers inland at the head of catchments. For example, the Ganges-Brahmaputra river system whose sediments form much of Bangladesh rises far inland in the Himalayas.
Therefore, the coast may be thought of as the area that shows a connection between land and ocean, and a coastal area defined (Ketchum, 1972) as:
the band of dry land and adjacent ocean space (water and submerged land) in which terrestrial processes and land uses directly affect oceanic processes and uses, and vice versa.
The key element of Ketchum’s definition is the interaction between oceanic and terrestrial processes and uses: coastal areas contain land which interacts with the ocean in some way, and ocean space which interacts with the land. Thus coastal areas:
• contain both land and ocean components;
• have land and ocean boundaries that are determined by the degree of influence of the land on the ocean and the ocean on the land; and
• are not of uniform width, depth, or height.