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Alavipanah, Seyedkazem 
  
The Use of Remote Sensing and GIS to Detect Salt Crust 
in the Iranian Deserts 
S.K.Alavi Panah * 
* Iran Desert Research Center, University of Tehran, Iran 
Salavipa @ chamran. ac. ut. ir 
Introduction 
The presence of surface crust is an obvious phenomenon seems indicative of soil 
degradation ( Stoops, 1984 ). The desert crusts in Iran are mainly situated in the salt 
lakes of the playas. Goudharzi ( 1970 ) showed that playa are the site of chloride, 
sulfate, nitrate and borate. Some studies showed the predominance of salt crust and salt 
flat zone in the Iranian playas. All the Iranian playas with different surface 
characteristics exist in areas where the annual evaporation is considerably greater than 
annual precipitation. With evaporation of water from the flooded playa, salt 
concentration increases until crystals of salts begin to be precipitated at its saturation 
point. The following types of crusts have been recognized in the Iranian deserts: 
a) desert crust or soil crust with a bright surfaces that are usually up to 3 to 5 mm thick, 
b) Salt crust is as a result of evaporation from shallow water table. 
Alavi panah S.K. et al, 1999 reported that the desert crusts are characterized by a very 
high reflection and the more the desert crust is destroyed, the more the reflection of the 
original material will dominate the overall reflection and mainly this correspond with a 
lower reflection. The salt lakes as a source of non- metallic materials have not 
received much attention. The main reason may be attributed to the limitations of 
trafficability and harsh climate. The current study is concerned with salt crust types and 
the capability of remotely sensed data ( Landsat TM data ) for delineating of salt crust 
from desert crust. Because the capability of Landsat TM data for detection of the salt 
crust diversity and purity is not well known, we attempted to use the remotely sensed 
data from Landsat TM on Qom and Ardakan salt zones . 
Materials and Methods : 
Landsat satellite images and other ancillary data are used for the study of salt crust 
in the Ardakan and Qom salt lakes. The 7 TM bands dated from September 1991, have 
been used for this study. To study the information content of TM band on the two 
studied areas, the following attempts were made ( Figure 1 y 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 
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