144
C.I.S. Pater
Spring tide level was adopted as the mean level for the seaward base of the
embankments. The alternatives to this is to adopt one spring high tide level for the
whole embayment or to apply a vector breakline with z values that vary along its
length corresponding to the changing mean spring high tide level. For the
‘Approaches to Boston’ case study, the Tabs Head level was adopted with converted
Environment Agency data providing levels for the embankment.
Concerning the historical chart record, analysis is possible between editions
that were produced to a consistent methodology as exemplified by the HR Wallingford
analysis in 1953. However a direct link with modern surveys is not possible.
Temporal analysis is therefore only possible for the Wash since 1985 with the
publication of chart number 1200. However, this edition does not provide a complete
coverage of the embayment, nor does the adjacent chart (number 108). The only chart
that does cover the whole of the Wash also includes the shoreline as far north as
Flamborough Head and is produced at a scale of 1:150,000. Although this provides
coverage of a regional scale littoral cell, the data content is minimal and therefore of
no use in GIS-based modelling.
Before operational GIS can be implemented in the coastal zone a greater level
of consensus, co-ordination and integration of coastal survey work above and below
LAT is required. A means must be found for publishing local soundings within
national standards that are of real use to near-shore geomorphology. A possible
solution could be the assimilation of port survey and intertidal profile within a
separate, inshore topographic chart publication to be produced at one scale (e.g. 1:25
000), for the entire UK coastline. This would produce the viable template for an
effective GIS. The GIS could then be used to maintain a viable inshore chart record
through the direct assimilation of data generated from concurrent monitoring.
Suitability of Analysis within a GIS
The potential contribution of GIS to the examination and monitoring of the interface
between the sea and the land is considerable. This can take the form of a system
constructed for the spatial analysis of one location (for example an embayment, a subcell or cell) or one feature at one location (see Table 1). However, the issue of the
survey mosaic is worthy of consideration when evaluating the functionalism of GIS in
relation to available data resources. A chart source data diagram on a published chart
reveals how it is composed of a survey mosaic that varies both spatially and temporally
(Fig. 7). Those areas that fall outside of a frequently surveyed zone will have
bathymetric and intertidal data derived from surveys conducted in preceding decades.
Given the dynamic nature of this embayment, using the published HO chart record
may provide a reasonable level of detail for individual areas, but fail to provide a
consistent record of topography over a wider area.
C.I.S. Pater
Spring tide level was adopted as the mean level for the seaward base of the
embankments. The alternatives to this is to adopt one spring high tide level for the
whole embayment or to apply a vector breakline with z values that vary along its
length corresponding to the changing mean spring high tide level. For the
‘Approaches to Boston’ case study, the Tabs Head level was adopted with converted
Environment Agency data providing levels for the embankment.
Concerning the historical chart record, analysis is possible between editions
that were produced to a consistent methodology as exemplified by the HR Wallingford
analysis in 1953. However a direct link with modern surveys is not possible.
Temporal analysis is therefore only possible for the Wash since 1985 with the
publication of chart number 1200. However, this edition does not provide a complete
coverage of the embayment, nor does the adjacent chart (number 108). The only chart
that does cover the whole of the Wash also includes the shoreline as far north as
Flamborough Head and is produced at a scale of 1:150,000. Although this provides
coverage of a regional scale littoral cell, the data content is minimal and therefore of
no use in GIS-based modelling.
Before operational GIS can be implemented in the coastal zone a greater level
of consensus, co-ordination and integration of coastal survey work above and below
LAT is required. A means must be found for publishing local soundings within
national standards that are of real use to near-shore geomorphology. A possible
solution could be the assimilation of port survey and intertidal profile within a
separate, inshore topographic chart publication to be produced at one scale (e.g. 1:25
000), for the entire UK coastline. This would produce the viable template for an
effective GIS. The GIS could then be used to maintain a viable inshore chart record
through the direct assimilation of data generated from concurrent monitoring.
Suitability of Analysis within a GIS
The potential contribution of GIS to the examination and monitoring of the interface
between the sea and the land is considerable. This can take the form of a system
constructed for the spatial analysis of one location (for example an embayment, a subcell or cell) or one feature at one location (see Table 1). However, the issue of the
survey mosaic is worthy of consideration when evaluating the functionalism of GIS in
relation to available data resources. A chart source data diagram on a published chart
reveals how it is composed of a survey mosaic that varies both spatially and temporally
(Fig. 7). Those areas that fall outside of a frequently surveyed zone will have
bathymetric and intertidal data derived from surveys conducted in preceding decades.
Given the dynamic nature of this embayment, using the published HO chart record
may provide a reasonable level of detail for individual areas, but fail to provide a
consistent record of topography over a wider area.