Geography Reference
In-Depth Information
GIS-Based Models as Tools for
Environmental Issues:
Applications in the South of Portugal
Jorge M. G. P. Isidoro, Helena M. N. P. V. Fernandez,
Fernando M. G. Martins and João L. M. P. de Lima
Additional information is available at the end of the chapter
http://dx.doi.org/10.5772/48218
1. Introduction
Geographical Information Systems (GIS) simulate a given geographic space in a
computational environment, allowing to store, map and analyse large amounts of
georeferenced data (
e.g.
, Umbelino
et al.
, 2009). GIS were converted into a powerful tool in
regional natural resources assessment, as it permits a speedy integration and representation
of several biophysical attributes (
e.g.
, Bastian, 2000; Bocco
et al.
, 2001) from diverse origins
such as,
e.g.
, topographic, cartographic, photogrametric, GPS and remote sensing.
The integration of Digital Terrain Models (DTM) in GIS leads to the emergence of
methodologies to represent and simulate the real-word, complementing the use of thematic
environmental information (
e.g.
, Felicísimo, 1999). A DTM is a numerical representation of a
variable obtained from a discrete set of points, with well-known cartographic coordinates,
which distribution allows calculating, by interpolation, that variable for any arbitrary point
(Fernandez, 2004). If the mesh of points is altitude-related, the DTM is designated as a
Digital Elevation Model (DEM). From a DEM, it becomes easy to attain topographic-derivate
models (
e.g.
, slopes, orientations, curvature and visibility, shadowed and exposed areas).
Many authors have used DEM processing techniques to automatically extract geographic
features (
e.g.
, Herrington & Pellegrini, 2000; MacMillan
et al.
, 2000; Burrough
et al.
, 2001;
Jordán
et al.
, 2007b; Zavala
et al.
, 2005a, 2007), hydrologic structures (
e.g.
, Flanagan
et al.
,
2000; Maidment, 2000), erosive processes (
e.g.
, Zavala
et al.
, 2005b), vegetation habitats (
e.g.
,
Anaya-Romero, 2004; Anaya-Romero
et al.
, 2005; Jordán
et al.
, 2007a; Pino
et al.
, 2010),
among other uses.
