Integrated Geographical Information Systems
Poulicos Prastacos
Institute of Applied and Computational Mathematics Foundation for Research
and Technology-Hellas (FORTH)
Geographic Information Systems (GIS) are used for capturing, storing,
processing analyzing and visualizing geo-referenced data. A GIS is not just
a DBMS since in addition to the storage capabilities it includes spatial
operators which permit the manipulation of spatial data. GIS in the past
have been used primarily for the production of digital maps for resources
management and management of land information systems. However, in the last
10 years with the wide availability of digital map data and the emergence
of desktop mapping systems, GIS are applied in many different fields ranging
from marketing to environmental planning and from city planning to water
resources management.
Recently, a new trend is emerging where GIS systems are combined with analytical,
mathematical models to form spatial decision support toolkits. In these
integrated systems the GIS is used to handle the spatial data and provide
a user friendly interface to the often complex models, while the analytical
models are used to simulate our knowledge about events in the real world.
Such toolkits are transferable, permit users to operate the models without
having a complete knowledge of the intricacies of the model or the data
structures and could be used for guiding policy makers in evaluating the
impact of alternative decisions.
The future of GIS will be driven by the applications. Some of these integrated
applications can be the subject of Mediterranean co- operation since most
of the problems they solve are common to most countries. Three areas of
research are outlined in the remainder of this paper. The first centres
on the development of decision support systems for managing water resources,
while the second is related to the design of a system for urban planning.
Finally the third ipotential Mediterranean collaboration includes the development
of electronic libraries for making GIS data widely available.
Management of water resources
Water is one of the most precious resources on both sides of the Mediterranean
sea. There is no doubt that there is a need for toolkits that combine GIS
with various models which could be used for water management, evaluation
of candidate decision alternatives and water resources protection and remediation.
They could support decision making for:
- Pollution control (surface water quality analysis, groundwater quality
analysis and urban water planning and management)
- Water utilization (management of water for irrigation, water resources
monitoring, assessment of surface water resources, urban water planning
and management, planning of irrigation and drainage systems, crop selection
and other)
- Flood control (flood control management, flood damage analysis, erosion
management, planning of storm water systems, risk assessment (scenario building)
The components of such a system will include data and models. The data could
include information on economic activity, hydrography, elevation, land cover
and land use, soil characteristics etc. Some of these datasets can be obtained
from remote sensing while others can be captured from paper maps or using
the Global Positioning System (GPS). The models to be combined in such applications
are mostly available presently and could include erosion, storm water and
flood control management models, precipitation and evapotranspiration models,
surface water quality models, groundwater models, rainfall-runoff models
and others.
A study is underway at FORTH to develop an integrated modelling system for
the water resources in the Messara Valley of Crete, an area in the south
of Crete where intensive agriculture has resulted in groundwater level changes.
The objective is to determine the processes that govern the hydrological
budget of the semi-arid Messara Valley and to assess the impact of changes
in irrigation methods and selection of crops.
Urban planning
Sixty percent of the population lives in large urban areas. The overpopulation
and the lack of planning have resulted in serious congestion and environmental
problems. GIS based decision support tools could be used for analyzing growth
patterns, promoting economic development, guiding activity location, managing
the urban area in better ways and protecting the environment. They could
assist in planning for:
- Economic activity development (household, firms and industry location
patterns, travel behavior analysis, economic growth alternatives, land use
policies)
- Operational management (location of various facilities, provision
of services, management of day to day activities (traffic etc.), public
transportation, sanitation, waste collection etc.)
- Improved environment quality (air quality, waste, emissions etc.)
The data to be included in such a system depend on the availability and
the scale of application. They could include information on the street network,
land use, geocoded directory of businesses and available "developable"
sites, statistical boundaries, cadaster and others. While the analytical
models could include econometric, land use forecasting, trip distribution,
modal split, trip assignments, emission dispersion, air quality, routing
and location - allocation models.
Such a system is being developed presently for the San Francisco, California
metropolitan region with the assistance of FORTH researchers. The objective
is to develop a GIS based set of tools for policy analysis and use them
for congestion management, and long term forecasting. The centrepiece of
the systems is the POLIS model which is used for projecting future location
of firms and households and travel flows.
Making spatial data widely available
One of the characteristics of the GIS applications is their heavy requirements
in data availability and information systems interoperability. The databases
needed are usually very large and seldom have the same format. They are
produced by different organizations and stored in diverse information systems.
Although a vast amount of data already exists in digital form they are mostly
available by specialized users. There is a need therefore to build data
repositories (digital libraries) that can deliver data on demand, standardize
data format, reformat data on the fly.
These on-line systems could be developed using World Wide Web technology.
They should include search engines that can handle distributed databases,
display functions for vector and raster data, metadata facilities for describing
the various datasets, and functions for linking map data with other information
(statistical, user data etc.). Presently few such systems are available.
They are mostly used for displaying available datasets and the interaction
with the user is limited.
Examples of research in this area is the system set up by National Land
Survey of Finland, a library for all map datasets in Finland, the iBadgeri
system in pilot stage for the San Francisco Bay Area that integrates all
digital geographic data available for that area the MAGIS system developed
by FORTH for Komunedata, Denmark that permits real estate agents to have
access to cadaster data and the InfoCharta (tm) system under development
in Greece that includes detailed street maps for the Athens area and permits
users to query the library to locate addresses and find points of interest
interactively.