Geoscience Reference
In-Depth Information
Salinity
High
Medium
Low
Diseases incidence
High
Medium
Low
Water quality
Good
Average
Bad
Shrimp Yield
Low
Medium
High
Fig. 19.1
Example of different layers (FAO
2003
)
originally developed for a specific purpose (e.g., the processing of data from satellite
and aerial surveys) and subsequently evolved into more sophisticated systems.
Regardless of their origin or their purpose, all GIS perform a set of basic functions
including the
management, transformation, analysis and visual presentation
of
spatially referenced information.
The
management
of spatial and attribute data refers to the need to input, store
and handle large amounts of data that may come from different sources (e.g., public
records, company files, etc.) or that may be available in different formats. As noted
by Murray (
2010
), system management is often related to representation issues and
whether a raster and/or vector view of space is adopted. The
transformation
of
information reflects the need for georeferencing i.e. for linking each data item to
its location in a common coordinate system. This allows different data sets to be
linked together based on the fact that they refer to the same location. Each data set
constitutes a different layer of information. New layers may then be produced by
aggregating, converting or overlaying existing layers with each other, as shown in
Fig.
19.1
(FAO
2003
). The figure depicts data related to a disease affecting shrimps
intheseaandshowshowGISmaybeusedtoanalyze whether in a certain area there
is a relation between the occurrence of this disease in shrimp farming and parameters
such as water quality in the ponds or major canals, salinity level, feeding levels, etc.
