Environmental Engineering Reference
In-Depth Information
By the very nature of the complex tasks involved, different methodologies can be an
option while developing new systems, for instance modelling, decision theoretic approaches,
artificial intelligence, geographical analysis, statistics and many more. A GIS can play the
role of an EDSS whenever a territorial aspect is taken into account and if it is enhanced with a
decision support module. So a GIS itself is often taken into account as a decision making
system, and, in this case, is often referred to as GIDSS. In general, there may be some
misunderstanding on what a GIS is, so it seems to be worthwhile to explain its role as an
EDSS related to territorial problems.
A GIS, as many other modern information systems, is a complex collection of
information processes allowed by a great number of hardware, software and communication
technologies, with which the users, characterized by different competences and different
objectives, can interact. In addition, a GIS is the fundamental tool to define, model and
implement many information/knowledge/decisional class of problems. The continuous
growing of the anthropisation of the territory more and more needs an accurate monitoring
action of the environment, in order to evaluate and plan the necessary interventions for the
protection of the environmental quality and of the health of the population. In general, a GIS
aims at filling the information gap between the status of the natural or anthropic environment
(in a wide meaning of the term, such as, for example, a forest, a river, an expanse of sea, but
also a city, its traffics or an industrial district) and a set of persons generally defined as
“decision makers” who can select the most appropriate actions for the environmental
protection.
A GIS can be taken into account as a layered information system
.
Each layer, which may
be more or less distributed, can offer a reliable service to the higher layers, and the link
between adjacent layers is guaranteed by an adequate telematics communication.
The first level, from bottom to top, can be defined as the “environmental monitoring
layer”, whose task is to acquire information from the environment by the use of sensors, in a
broad sense, including in this definition, for example, rain gauges, anemometer, cameras for
map data acquisition from satellites, people collecting water samples and related water quality
analysis processes ... In the “environmental monitoring” layer, sensors and related software
for data acquisition and communication transfer are present and distributed in space,
providing quite different content and formats of heterogeneous data.
The second level can be defined as the “DataBase Management System (DBMS) layer”.
In this layer, data coming from telematics connections or from storage supports are modelled
and stored in one or more databases. The most frequently used data models are based on the
relational paradigm, and these data are often centralized, such as for example at local or
regional authorities. From a software architecture and applications point of view many are the
trends in this layer, such as for example, client server web based architectures, java
applications, open software applications, object oriented databases ... In general, a common
approach to data modelling in this layer is to define as much as possible a relational data
architecture, leaving map and cartographic data to specific proprietary data models related to
GIS software for efficiency reasons.
The third level can be defined as a “data analysis, synthesis and processing layer”, and it
can be generally divided into two sub-components, of which at least one is always present in
a GIS: the “environmental modelling sub-layer” and the “GIS software sub-layer”. In the
environmental modelling sub-layer, software tools are introduced in relation to models,
generally mathematically formulated, describing the behaviour of an environmental system
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