Dynamic Segmentation in the Coastal Information System
375
Dynamic Segmentation
Dynamic segmentation links attributes, such as geomorphologic form and material, to
a linear spatial object, such as the coast, by use of a distance referencing system. In the
example shown in Fig. 2, the coastal form type 'cliff,' represented on the landward side
of the coast, extends from a distance of 461839.406 m to 462877.188 m. Similarly, the
coastal form type 'beach,' on the seaward side of the coast, extends from a distance of
462719.000 m to 462789.000 m. These distances are stored in a database table as
'from' and 'to' items. Tables 1, 2 and 3 show the definition of items in the database and
attribute data associated with the two linear coastal form types presented in Fig. 2.
Coastal forms represented as points can also be managed this way by storing a single
value for the distance along the coast in the database table. The linear extent or
position of these forms can be dynamically created by the CIS as distinct linear or point
objects. Accordingly, adjacency relationships between coastal geomorphologic forms
and materials are inherent in the employment of dynamic segmentation.
In this study three types of adjacency relationships are used. Adjoining
relationships are end-to-end relationships between coastal units. Across-shore
relationships are those between coastal units in the foreshore and backshore.
Overlapping relationships are those where coastal units overlap along the coast. We
have not distinguished between these three types of adjacency relationships for the
analysis presented in this chapter.
Methods
A program was written in Arc Macro Language to analyze the along-shore and acrossshore sequences of coastal geomorphologic forms. The program was designed to
include only linear coastal forms sorted in ascending order of distance along the coast
(database item 'to' in Table 1). The program steps along the coast examining the binary
and tertiary sequences as each linear form is encountered. It then stores the number of
occurrences of each unique relationship in one of the two database sequence tables.
Sequence data were collected for coastal form 'type' and material 'supertype' on several
selected data sets outlined in the discussion below. In this program, a binary adjacency
relationship is the relationship between a coastal unit and an adjacent coastal unit with
the next highest 'to' value regardless of whether the relationship is across shore or
along shore. A tertiary relationship occurs between a coastal unit and the following two
coastal units irrespective of whether the relationship is across shore or along shore.
375
Dynamic Segmentation
Dynamic segmentation links attributes, such as geomorphologic form and material, to
a linear spatial object, such as the coast, by use of a distance referencing system. In the
example shown in Fig. 2, the coastal form type 'cliff,' represented on the landward side
of the coast, extends from a distance of 461839.406 m to 462877.188 m. Similarly, the
coastal form type 'beach,' on the seaward side of the coast, extends from a distance of
462719.000 m to 462789.000 m. These distances are stored in a database table as
'from' and 'to' items. Tables 1, 2 and 3 show the definition of items in the database and
attribute data associated with the two linear coastal form types presented in Fig. 2.
Coastal forms represented as points can also be managed this way by storing a single
value for the distance along the coast in the database table. The linear extent or
position of these forms can be dynamically created by the CIS as distinct linear or point
objects. Accordingly, adjacency relationships between coastal geomorphologic forms
and materials are inherent in the employment of dynamic segmentation.
In this study three types of adjacency relationships are used. Adjoining
relationships are end-to-end relationships between coastal units. Across-shore
relationships are those between coastal units in the foreshore and backshore.
Overlapping relationships are those where coastal units overlap along the coast. We
have not distinguished between these three types of adjacency relationships for the
analysis presented in this chapter.
Methods
A program was written in Arc Macro Language to analyze the along-shore and acrossshore sequences of coastal geomorphologic forms. The program was designed to
include only linear coastal forms sorted in ascending order of distance along the coast
(database item 'to' in Table 1). The program steps along the coast examining the binary
and tertiary sequences as each linear form is encountered. It then stores the number of
occurrences of each unique relationship in one of the two database sequence tables.
Sequence data were collected for coastal form 'type' and material 'supertype' on several
selected data sets outlined in the discussion below. In this program, a binary adjacency
relationship is the relationship between a coastal unit and an adjacent coastal unit with
the next highest 'to' value regardless of whether the relationship is across shore or
along shore. A tertiary relationship occurs between a coastal unit and the following two
coastal units irrespective of whether the relationship is across shore or along shore.