Aerial Photographic Techniques in
Pollution Detection
JAMES P. SCHERZ, Assistant Professor
WILLIAM C. BOYLE, Associate Professor
Civil Engineering Department
The University of Wisconsin
Madison, Wisconsin
DONALD R GRAFF, Photogrammetrist
ITEK Corporation
Lexington, Massachusetts
INTRODUCTION
Water pollution, which looms as one of the major domestic problems today in
this country, has prompted extensive studies on the economical treatment of waste
water from both municipalities and industry. In addition, there have been a
number of studies conducted to evaluate the cause and effect relationships related to the pollution of our water courses. In any comprehensive pollution
abatement program, it is essential that guidelines for water quality be established
and enforced.
Effective enforcement of water quality standards requires extensive surveillance which represents the expenditure of a great deal of time and money. Aerial
photography represents a potential technique to assist in the surveillance program.
With inexpensive cameras, films and filters, it is possible to fly over a river and
detect and permanently record on film major sources of pollution and their influence on the watershed.
Standberg (16, 20), of ITEK Corporation showed that by use of various combinations of filters and special tilms it is possible to photograpn and record various
pollutants entering water bodies. He also indicated that in some cases there may
be a correlation between photo imagery and dissolved oxygen concentration (20).
Oswald (14) indicated that the amount of infrared energy that is reflected from
algae ponds is a function of the oxygen content within the algae waters. Fraga (7)
described aerial photographic techniques being used to find pollution in Lake Ta-
hoe.
Although remote sensing of water pollution will not replace ground surveys it
is almost certain to be a very useful tool in more effective ground work.
THEORETICAL BACKGROUND
Since aerial photographic imagery is caused by reflected light, it is necessary
to consider the nature of the sun's energy as it reaches the earth's surface. Although dust and various chemicals in the atmosphere absorb a significent proportion of the energy, a wide spectrum of energies do reach the surface (Figure 1).
The visible light of wavelengths 0.4 to 0. 7 microns is subdivided into the colors
of blue, red, green while wavelengths shorter than 0.4 are ultraviolet and longer
than . 7 are infrared energy.
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