The Management Plan Wadden Sea and its Visualisation
107
plan, but also for the actual management afterwards. Additionally, the Directorate of
the North-Netherlands already had an ArcInfo system at their disposal.
The spatial information had to be suitable for visualisation as well for
analyses. Therefore, agreements were made on the co-ordinate system, the level of
details of the data, the description of the data, the use of a metadata system and a data
exchange format. Next a data model was set up for the GIS.
The Sector Notes
For the first draft of the data model it was assumed that there would be a total of thirtysix themes or entities, spread over eight different sectors, plus the topography. Later on
a few more themes were added.
The national rectangular RD co-ordinate system was chosen, based on the
stereographic projection and with elevation data (in metres) based on Amsterdam Zero
(NAP). The same systems are used on topographic maps (scale 1:10.000 to 1:100.000)
in the Netherlands.
For the construction of the GIS database a deliberate choice was made in
favour of the 1:250.000 scale. This scale makes it possible to also produce maps at a
scale 1:100.000 or 1:500.000. In the latter case the Dutch Wadden Sea fits on an A3size sheet. The initial wish was for a scale of 1:50.000 because several themes were
already available at that scale. But, most of the information needed was not yet
digitally available and it would have been too great an effort to collect these at such a
detailed scale; and, for policy purposes that level of detail is not necessary. For a
policy-maker it is sufficient to use maps, for example, with only waterways marked.
Only a maintenance officer (and a sailor of course) needs a map or chart with the exact
location of the various buoys and beacons. It was also intended to update the database,
to support the mandatory annual evaluation and five-year revision of the Management
Plan. A GIS database at the scale of 1:50.000 would be too large and too time
consuming to maintain for that purpose. For the description of the meta-information a
programme called GeoKey was chosen. At that time a prototype was available but
meanwhile GeoKey has became a standard within Rijkswaterstaat.
During the compilation of the sector notes the text and the maps advanced
together. This is quite unique, since normally attention to maps and illustrations is
only given after the text is completed. All 15 different maps were plotted straight from
ArcInfo at a scale of 1:250.000 on a HP DesignJet inkjet printer and discussed at
several meetings. Every adaptation was immediately carried out in the GIS and the
revised maps were presented on the next meeting. In this way, the so-called
“discussion maps” grew together with the sector notes. Finally these maps were
reduced to a scale of 1:500.000 to fit on an A3-size sheet as a supplement for the final
printed sector notes. These serve as background-documents for the specialist. For each
sector map some 350 copies were printed (see Fig. 1) on a Xeikon digital printing
press, straight from an ArcInfo postscript-file without making final films or printing
plates. This turned out to be the most attractive option, considering quality, cost and
delivery time.
107
plan, but also for the actual management afterwards. Additionally, the Directorate of
the North-Netherlands already had an ArcInfo system at their disposal.
The spatial information had to be suitable for visualisation as well for
analyses. Therefore, agreements were made on the co-ordinate system, the level of
details of the data, the description of the data, the use of a metadata system and a data
exchange format. Next a data model was set up for the GIS.
The Sector Notes
For the first draft of the data model it was assumed that there would be a total of thirtysix themes or entities, spread over eight different sectors, plus the topography. Later on
a few more themes were added.
The national rectangular RD co-ordinate system was chosen, based on the
stereographic projection and with elevation data (in metres) based on Amsterdam Zero
(NAP). The same systems are used on topographic maps (scale 1:10.000 to 1:100.000)
in the Netherlands.
For the construction of the GIS database a deliberate choice was made in
favour of the 1:250.000 scale. This scale makes it possible to also produce maps at a
scale 1:100.000 or 1:500.000. In the latter case the Dutch Wadden Sea fits on an A3size sheet. The initial wish was for a scale of 1:50.000 because several themes were
already available at that scale. But, most of the information needed was not yet
digitally available and it would have been too great an effort to collect these at such a
detailed scale; and, for policy purposes that level of detail is not necessary. For a
policy-maker it is sufficient to use maps, for example, with only waterways marked.
Only a maintenance officer (and a sailor of course) needs a map or chart with the exact
location of the various buoys and beacons. It was also intended to update the database,
to support the mandatory annual evaluation and five-year revision of the Management
Plan. A GIS database at the scale of 1:50.000 would be too large and too time
consuming to maintain for that purpose. For the description of the meta-information a
programme called GeoKey was chosen. At that time a prototype was available but
meanwhile GeoKey has became a standard within Rijkswaterstaat.
During the compilation of the sector notes the text and the maps advanced
together. This is quite unique, since normally attention to maps and illustrations is
only given after the text is completed. All 15 different maps were plotted straight from
ArcInfo at a scale of 1:250.000 on a HP DesignJet inkjet printer and discussed at
several meetings. Every adaptation was immediately carried out in the GIS and the
revised maps were presented on the next meeting. In this way, the so-called
“discussion maps” grew together with the sector notes. Finally these maps were
reduced to a scale of 1:500.000 to fit on an A3-size sheet as a supplement for the final
printed sector notes. These serve as background-documents for the specialist. For each
sector map some 350 copies were printed (see Fig. 1) on a Xeikon digital printing
press, straight from an ArcInfo postscript-file without making final films or printing
plates. This turned out to be the most attractive option, considering quality, cost and
delivery time.