Geoscience Reference
In-Depth Information
A
B
Figure 3-22.
Eroding cliff on the North Sea coast at Bovbjerg, Jylland, Denmark. A. View toward the north with
good illumination of the scene; note shadow of lighthouse on right side. B. View of same cliff looking toward the
south. Sun glint from North Sea and heavy shadows on cliff face result in poor depiction of details. Kite aerial
photographs; after Aber, Marzolff and Ries (2010, Fig. 4-12).
3.3 Maps and geographic information
systems
collecting, storing, analyzing, and displaying
georeferenced information about the Earth
(Nyerges 1993).
GIS combines traditional surveying, geodesy,
and cartography with remote sensing, database
systems, global positioning system (GPS), and
sophisticated statistical, spatial, and temporal
data analysis (e.g. Burrough 1988; Chang 2008).
It has become a primary method for wetland
research. One example of this approach is docu-
menting playas of the southern High Plains of
the central United States (Fig. 3-23). Previous
estimates for the total number of playas in
this region varied greatly; Steiert and Meinzer
(1995) cited a value of 25,000 with 2000 in
Kansas. Other estimates ranged as high as
60,000 total for the region with 10,000 in Kansas
(Evans 2010). A GIS analysis of high-resolution
aerial imagery, digital raster graphics, and soil
data has revealed more than 22,000 playas in
Kansas alone (Fig. 3-24), more than twice the
previous high estimate (Kansas Geospatial Com-
munity Commons 2010).
Having emphasized the advantage of GIS for
wetland research, it is wise to note some cau-
tions. Maps and GIS databases are never perfect
pictures of the so-called real world. Field meas-
urements are subject to errors of accuracy and
precision. Aerial photographs and satellite
A map is a graphic representation or scale
model of spatial concepts. It is a means for
conveying geographic information, namely
those physical, biological, and cultural phenom-
ena related to wetlands. Maps are a universal
medium for communication, easily understood
and appreciated by most people, regardless of
language or culture. Incorporated in a map is
the understanding that it is a “snapshot” of an
idea, a single picture, a selection of concepts
from a constantly changing database of geo-
graphic information (Merriam 1996).
Geographic information systems (GIS), also
known as geographic information science, is
a multidisciplinary technology that emerged
in the 1970s and 80s and became a routine
working method in the 1990s. GIS represents
a major shift in the cartographic paradigm.
In traditional (paper) cartography, the map
was both the database and the display of geo-
graphic information. For GIS, the database,
analysis, and display are physically and concep-
tually separate aspects of handling geographic
data. Geographic information systems comprise
computer hardware, software, digital data,
people, organizations, and institutions for
