CoastGIS’99: geomatics and coastal environment
This coastline will be changed soon by the BCN-25 (1:25,000 scale) of
the IGN. Because of the continuous coastal modification, we consider that
in future there will be two coastlines incorporated into the GIS, the
legal one and the real one.
The problem of the diversity of information sources
The information incorporated into the marine GIS project mainly comes
from the SGPM (studies on Marine Reserves and Artificial Reefs) and
the IEO (depth, nature of the seabed, fisheries mapping, etc., of the
continental shelf), but also from other national (land clata, tectonics,
morphology, lithology, etc.) or regional agencies (detailed local research).
Working rules are different in every institution, sometimes they are
somewhat standardised but they use different scales and the studies
that they make are concentrated in specified areas or focus on a specific
scope (seeking areas to remove sand for coast regeneration, studies on
beach stability, etc.), and rhey do not standardise the collection, management and organization of related information, which is important
afterwards. Moreover, as there is no generally accepted nomenclature,
maps and reports on an area have class divisions which are almost
impossible to homogenize.
For this reason, the information collected cloes not have spatial, temporal or class continuity, and therefore the results of studies and research
by different authors on the same area are usually difficult to correlate.
Objectives are also different, as well as the precision in collecting data,
the scale of analysis and the meaning or the interpretation of the same
element.
Therefore, in most cases the information gathered should be synthesized
and filtered or even reinterpreted (homogenizing it and adapting it to
the SIGMAZAL project objectives) according to the elements, classes,
coverages and tables previously defined in the conceptual structure.
We also concluded that final users (the administration mainly) did not
consider each project as part of a larger whole, nor did they have uniformly defined information layers. As a result, it was necessary to
prepare a document with the standards for studies to be carried out by
SGPM thereafter.
Difficulties when defining classes or values in some information layers
The meaning of some elements varies according to the observer’s point
of view (ITGE, 1990; Ballester et al., 1999). Thus one main difficulty
has been to determine the best classes defining the seabed, which
depends on the objectives of the study and of the specialist carrying it
out (the interpretation and classification of each phenomenon will be
different for a biologist, ageologist or an engineer). Although there are
commonly accepted classifications (Krumbein, 19.38; Folk, 1954, Shepard, 1954; Meinesz et al. 1 983), the definition of the seabed can vary
considerably m accuracy or in type (lithology, granulometry, mineral
300
This coastline will be changed soon by the BCN-25 (1:25,000 scale) of
the IGN. Because of the continuous coastal modification, we consider that
in future there will be two coastlines incorporated into the GIS, the
legal one and the real one.
The problem of the diversity of information sources
The information incorporated into the marine GIS project mainly comes
from the SGPM (studies on Marine Reserves and Artificial Reefs) and
the IEO (depth, nature of the seabed, fisheries mapping, etc., of the
continental shelf), but also from other national (land clata, tectonics,
morphology, lithology, etc.) or regional agencies (detailed local research).
Working rules are different in every institution, sometimes they are
somewhat standardised but they use different scales and the studies
that they make are concentrated in specified areas or focus on a specific
scope (seeking areas to remove sand for coast regeneration, studies on
beach stability, etc.), and rhey do not standardise the collection, management and organization of related information, which is important
afterwards. Moreover, as there is no generally accepted nomenclature,
maps and reports on an area have class divisions which are almost
impossible to homogenize.
For this reason, the information collected cloes not have spatial, temporal or class continuity, and therefore the results of studies and research
by different authors on the same area are usually difficult to correlate.
Objectives are also different, as well as the precision in collecting data,
the scale of analysis and the meaning or the interpretation of the same
element.
Therefore, in most cases the information gathered should be synthesized
and filtered or even reinterpreted (homogenizing it and adapting it to
the SIGMAZAL project objectives) according to the elements, classes,
coverages and tables previously defined in the conceptual structure.
We also concluded that final users (the administration mainly) did not
consider each project as part of a larger whole, nor did they have uniformly defined information layers. As a result, it was necessary to
prepare a document with the standards for studies to be carried out by
SGPM thereafter.
Difficulties when defining classes or values in some information layers
The meaning of some elements varies according to the observer’s point
of view (ITGE, 1990; Ballester et al., 1999). Thus one main difficulty
has been to determine the best classes defining the seabed, which
depends on the objectives of the study and of the specialist carrying it
out (the interpretation and classification of each phenomenon will be
different for a biologist, ageologist or an engineer). Although there are
commonly accepted classifications (Krumbein, 19.38; Folk, 1954, Shepard, 1954; Meinesz et al. 1 983), the definition of the seabed can vary
considerably m accuracy or in type (lithology, granulometry, mineral
300