However, with the advent of computers and digital imagery, attention has focused on the use of computer-assisted interpretation. Although the human eye still
brings a superior set of capabilities to the classification process, the speed and consistency of digital procedures make them very attractive. As a consequence,
the majority of classification projects today make use of digital classification procedures, guides by human interpretation.
There are two basic approaches to the classification process: supervised and unsupervised classification. With supervised classification, one provides a
statistical description of the manner in which expected land cover classes should appear in the imagery, and then a procedure known as a classifier is used to
evaluate the likehood that each pixel belongs to one of these classes. With unsupervised classification, a very different approach is used. Here another type
of classifier is used to uncover commonly occuring and distinctive reflectance patterns in the imagery, on the assumption that these represent major land cover
classes. The analyst then determinees the identity of each class by combination of experience and ground truth i.e., visiting the study area and observing the actual
cover types.
2.3 Decision Support System
While decision support is one of the most important function of a GIS, tools designed especially for this are relatively few in most GIS software. However, a
complete GIS software should include several modules specifically developed to aid in the resources allocation decision making process. These include modules
that incorporate error into the process, help in the construction of multi-criteria
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suitability maps under varying levels of trade off, and address allocation decision when there are multiple objectives involved. Used in conjunction with the other
components of the system, these modules provide a powerful tool for resource allocation decision makers.
The concept of decision support system DSS was first enunciated in 1970s by Scott Morton under term management decision systems. He defined
such systems as “interactive computer-based system, which help decision makers utilize data and models to solve unstructured problems”. Another definition was
also introduced by Keen and Scott Morton in 1978s that declare the “decision support system couple the intellectual resources of individuals with the
capabilities of the computer to improve the quality of decisions. It is a computer-based support system for management decision makers who deal with
semi-structured problems.” Furthermore, Moore and Chang 1980 define DSS as i extendable
systems, ii capable of supporting ad hoc data analysis and decision modeling, iii oriented toward future planning, and iv used at irregular, unplanned
intervals. Thereby, from several definition above and much more, we can simplify that DSS constitute an interactive, flexible, and adaptable computer-based
information system, specially developed for supporting the solution of a non-structured management problem for improving decision making. It utilizes
data, it provides easy user interface, and it allows for the decision maker’s own insight.
Aiding the deficiencies of human judgment and decision making has been a major focus of science through its history, because in many situations the quality
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of decisions is important, as particularly in complex systems, as management of organizational operations, industrial processes, or bidding processes.
2.4. Geological Hazards
