Ali Farrag, Farrag
The Role of SPOT Satellite Images in Mapping Air Pollution Caused by Cement Factories
Dr. Farrag Ali FARRAG
Assistant Prof. at Civil Engineering Dept.
Faculty of Engineering
Assiut University
Assiut, Egypt.
farrag(@acc.aun.eun.eg
Working Group IV/4
KEY WORDS : Image Processing, Mapping, Monitoring, Remote sensing, SPOT
ABSTRACT
Environmental analysis and monitoring of pollution are important tasks in Egypt and all over the world. In this study,
temporal SPOT satellite multispectral images were used for locating the horizontal dispersion of air pollution caused by
a cement factory that was constructed near Assiut City in Egypt. Two different working conditions of the factory were
analyzed. In the first one (1995), with average production rate 8341 Ton/day, the dust emission from the factory was not
properly controlled, while in the second one (1998), with average production rate 10577 Ton/day, the factory applied
optimum control on dust emission due to the constrains of the environmental lows which are taking place in Egypt
nowadays. The techniques of image interpretation, unsupervised classification, and image thresholding were used. This
approach allowed us to map the source of pollution and its aerial extent and to identify different degrees of
contamination intensities under the different working conditions. This study proved that multispectral SPOT images can
be used as a global tool for locating and monitoring air pollution phenomena caused by uncontrolled industrial pollution.
1. INTRODUCTION
The cement industry contributes to the economical growth, as an essential material for constructing different types of
buildings. However, in spite of the economical importance of this industry, it can be considered as one of the biggest
contaminators of the surrounding environment. The optimum technique for monitoring and modeling the behavior of the
environment should be based on the use of best available sources of information.
This study investigates the role of SPOT satellite images for mapping air pollution caused by cement factories. Although
the potential of using satellite data for mapping air pollution has been analyzed by some authors, the present study
concentrate on the practicality of analyzing the spectral information of temporal SPOT multispectral images to detect
and locate the air pollution around a cement factory under different working conditions. Two working conditions were
analyzed, the first one (1995) with average production rate 8341 Ton/day where the dust emission from the factory was
not properly controlled, while in the second one (1998) with average production rate 10577 Ton/day, the factory applied
optimum control on dust emission due to the constrains of the environmental lows which are taking place in Egypt
nowadays.
2. STUDY AREA AND DATA
The study area is located around a cement factory that was constructed in the west desert about 17 km to the west of the
center of Assiut City (Egypt). A location map showing the relative position of the cement factory and the surrounding
environment is given in Figure 1. This map is a part of topographic map, produced in 1991 by the Egyptian General
Surveying Authority (EGSA). Two SPOT multispectral images with 20 m ground resolution were the main data source
for this study. The SPOT images correspond to column 113 and row 296 of SPOT Grid Reference System (GRS). The
first image was captured by SPOT-2 on 25 July 1995, and the second image was captured by SPOT-4 on 11 August
1998. SPOT-1, 2, 3 and 4 are equipped with High-Resolution Visible (HRV) sensor that recording three bands in the
multispectral mode with 20 m ground resolution. Band 1 (the green band) covering the spectral band from 500 nm to
590 nm, band 2 (the red band) covering the spectral band from 610 nm to 680 nm , and band 3 (the near infra red band)
covering the spectral band from 790 nm to 890 nm [Michele 1981 and SPOT Magazine No 28 ( January 1998)].
Field measurements were carried out in order to determine the ground coordinates of the control points using Global
Positioning System (GPS) with differential correction technique.
46 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.
