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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
The evaluation of these parameters has been made on
representative areas from the three great structural-functional
areas of the big city (central area, middle-intermediary area,
peripheral area) where homogeneous areas were determined, in
urban land cover, depending on the radiometric average values.
By cumulating the data and reporting them to the existing
environmental quality standards we established the categories of
the environment quality and delimited, in a preliminary form,
the areas corresponding to these categories. The drawing of area
limits and the editing of the map were achieved using ArcInfo.
In order to apply the above method we focused on just one of
the six sectors of the city of Bucharest — sector 1 — this sector
presenting a great diversity of aspects (Figure 1). The map of
environmental quality that we obtained in this way must be
perfected by consulting topographical plans, aerial photographs
and live observations, consequently becoming a reliable
document in the project studies of urban remodeling. The
satellite image and the thematic derived map shall be included
in GIS, a modern instrument indispensable to improving the
management of Bucharest’s urban and metropolitan area.
3. CRITERIA AND PARAMETERS OF ESTIMATION OF
BUCHAREST’S URBAN ENVIRONMENT QUALITY BY
PROCESSING AND INTERPRETING HIGH
RESOLUTION SATELLITE IMAGES
3.1. The quality of the natural elements
The quality of each natural element is essential in determining
the sanitation of the urban environment. The analysis of high
resolution satellite maps makes it possible to represent in broad
lines the situation of air pollution and the condition of
oxygenated areas (parks, squares, lakes, canals) with the
possibility of calculating some important parameters concerning
sanitation.
- identifying air-pollution sources and reporting them to the
important constructed areas and green areas by
correlating them with the direction and the characteristics
of the winds (Figure 2).
Figure 2. A big residential district is under the influence of air
pollution from an industrial zone
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- determining and mapping the areas and lines of severe
air-pollution (chemical, micro-biological, phonic). These
correspond to the big central arteries and intersections
with extremely agglomerated traffic, the traffic axis
parallel to Dämbovita canal, the boulevards that make up
the inner circulation ring and especially the great
intersections on the axis north-south (Pietei Libere
Square, Victoriei Square, Charles de Gaulle Square,
Romanä Square, Universitätii Square, Unirii Square etc.).
From the analysis of IKONOS images we can approximate the
degree of air pollution caused by the gases emitted by cars (CO,
SO», NO, etc.) in a certain place (for instance, a big intersection
in the central area) by calculating the traffic intensity: we make
an inventory of the number of cars represented in the respective
intersection by the satellite images, we give 15 seconds to each
car for going through the intersection and we obtain the number
of cars passing through the intersection during an hour through
the place under consideration and knowing the composition of
gases emitted by a car we can approximate their concentration
for 1 hour, for 24 hours etc.
For instance on the basis of the satellite image in Universitätii
Square we made an inventory of 103 cars. Given the calculation
basis we have proposed it results that every minute 412 cars go
through the intersection and in an hour 12360 traverse the
crossroads (considering that 30 minutes per hour represent
overall car stop time) (Figure 3). This situation refers to the
most intense traffic period of the day, between 7.00 a.m. — 7.00
p.m. These cars produce in this square over 3 times the CO
maximum admissible concentration.
Figure 3. A possible evaluation of the pollution degree based on
traffic intensity in a determined place such as University Square
(Piata Universitatii), viewed from a satellite image.
- the repartition of oxygenated areas (especially of green areas)
and their relation to residential areas
The analysis of the IKONOS image allows us to calculate the
parameters concerning green areas reported to the entire city, to
sectors or to constructed areas: the weight of green areas, the
surface of green areas per inhabitant. These data are reported to
the standard values for an urban environment that would be
optimal from an ecological point of view (25-4 m°/ inhabitant:
25 m/ inhabitant — ideal; 4 m?/ inhabitant = minimum
admissible for the great metropolis ; WHO recommends 50 m?/
inhabitant). These values lay at the basis of the definition and
delimitation of the quality areas in the urban environment. The