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SOIL AND SAND MAPPING USING REMOTE SENSING DATA
by
FAROUK EL-BAZ
National Ain and Space Museum
Smithsonian Institution
Washington, 0C, 20560 USA
The spectral signatures of desert surfaces are easily distinguishable
in remote sensing data. Landsat data, for example, clearly show differences
in the reflectance properties of limestone rock, clayey playa deposits, and
dune accunulacions of quartz sand. Parts of the Western Desert of Egypt were
mapped in this way using Landsat images coupled with field checks. In some
cases, however, a thin mantle of one-grain thick deposits may mask the nature
of the soil below. Furthermore, clay-rich desert varnish on limestone or sand-
stone may give the spectral signature of clay deposits. Such distinctions
must be made based on field observations. An experiment was recently conducted
in conjunction with the second flight of the Space Shuttle Columbia. Samples
were collected from exposed rock rubbl&, soil and sand in the Kharga Oasis in
the Western Desert of Egypt. Mylar markers were placed on the desert surface to
identify the sampling sites in remotely-sensed data for correlation. Spectral
characteristics of these vegetation-free surfaces are correlated with data from
the Shuttle Multispectral Infrared Radiometer (SMIRR) and multispectral data from
Landsat.
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