| DATA 
t sources of data 
nterpretation and 
1ingful way. The 
tained results we 
e most important 
and TM thermal 
analysis. 
MIR wavelength 
iditions, but fore 
se as a result of 
conditions. 
S carried out on 
the places where 
depression was 
n of salt crust 
M images. Based 
urvey, the main 
re: medium soil 
soil. The water 
ned at a depth of 
n, the salt crust 
to moisture is 
salt crust, due to 
ardang and sand 
extremely arid 
nperature below 
rare and striking 
of hydroaeolian 
forms. Yardang 
iterials is one of 
' Iranian deserts. 
formed by wind 
] topography in 
ction. Yardangs 
between wind- 
vind. Wind and 
capes, such as 
cperienced great 
netic process in 
ly unstable area 
Lut Desert is surrounded by the mountain in the north, and 
south of Birjand and Nay-band mountain in the south, Kerman 
elevations in the West, Sistan and Blouchestan elevations in the 
East. In this study, the attention was mainly focused on 
Yardangs located in the southern part of Kerman city and the 
eastern part of Shahdad town. 
3. MATERIALS AND METHODS 
In this study, 7 bands of Landsat TM bands on two different 
areas of Meybod depression and Lut Desert were used to study 
the capability of Landsat TM bands in mapping surface 
condition with dry and wet surface. The dates of Landsat MSS 
data (1975) and Landsat TM data (1990) were used. Other 
information sources, such as topographic maps, geologic and 
geomorphologic maps were used. The field work as one as one 
of the most important steps were carried out. The methodology 
comprised of; 
l. Visual comparison between the standard FCC,s of MSS and 
TM images of the Meybod Depression 
2. Digital image classification 
3. Feature space analysis of the Lut area 
In this study, seven channels of Landsat Thematic Mapper dated 
24. June 1989 were used. The techniques of image processing 
such as, 1) False Color Composites (FCC), spectral rationing, 
Feature Space Analysis (Figure 1) and visual interpretation 
were used. 
4. RESULT AND DISCUSSION 
Meybod area: Visual comparison between the standard FCCs 
of MSS and TM images shows a photomorphic unit (PMU) on 
the TM FCC which could not be found on the MSS FCC . This 
PMU is characterized by a dark brownish salt crust on wet soil 
condition. In fact this visual interpretation suggests that wet 
soils has been developed in between the date of Landsat MSS 
satellite overpass (1975) and Landsat satellite overpass (1990). 
Personal interviewing with the farmers also confirmed the lack 
of a salt crust before 1975. 
Supervised classification of TM and MSS images shows some 
changes in the land cover in the period 1975-1990 (Figure 1). 
The MSS classification shows an absence of the salt crust class 
and TM classification shows its presence. This means that in 
period 1975-1990, this area is altered to salt crust and wet land 
condition. The change of the area into the wetland condition 
and then salt crust can be due to a number of reasons: Physical, 
chemical and biological agents may be the causes of wet land 
and salt crust formation in the period 1975-1990. 
Lut Desert: Figure 2 shows the feature space between TM 
band 1 and TM band 5. A close look at FS indicates the 
behavior of TM bands are different in view point of spectral 
separability. For example FS between band 2 and 5 indicates a 
fairly good spectral separability of training classes, especially 
wet salt affected area. A careful look to these FS,s shows that 
wet land classes can be separated by TM reflective bands of TM 
2, TM 5, TM 7 and TM thermal band. 
The salt crust and wet land is situated in a depression which is 
surrounded by higher land. As the DEM of the Meybod area 
shows, the developed salt crust is located in a depression lower 
than 1046 m asl. The difference between the mean elevation of 
the salt crust area and the surrounding cultivated areas is about 
20m. This shows the situation of the depression in relation to 
cultivated areas in the higher elevation. Comparison between 
the TM and MSS FCC,s (Figure la, b) shows also the 
extension of the vegetated area. Pale and pale red color shows 
the vegetated area on TM and MSS FCC,s of the Shahidieh 
Meybod area. Comparison between the TM and MSS 
classification images shows a better understanding of the 
development of urban and vegetation. It is notable that in these 
visual interpretation and comparison of the FCC,s and 
classification of TM and MSS images, the resolution 
discrepancy of the images must be taken into account. It means 
that the TM FCC or TM classified image shows some single 
pixels of the vegetation and urban classes that could not be 
found on MSS FCC or MSS classifications. This difference may 
be due to the higher spatial resolution of the TM images. But 
the aggregated pixels show that vegetation has considerably 
increased in the study period. The deep water table in the 
upland cultivated area dropped in period of 1975- 1990 
(personal conservation with expertise and farmers, 1995). This 
is due to the overdraft of the ground water table. The extension 
of the cultivated area and urban growth can have a major 
contribution to water consumption. Therefore we may conclude 
that there are some factors accelerating the drainage water and 
lateral movement toward the depression: 
l) extension of cultivated area which are irrigated by flood 
irrigation system; 
2) urban growth and increasing water consumption; 
3) precipitation, run-off, evaporation and evapotranspiration, 
deep percolation and etc. 
Some factors such as precipitation evaporation are almost 
constant in the study period and the effect of some other factors 
such as run-off seems to be less important than the increase of 
water consumption for flood irrigation and urban consumption. 
Flood irrigation is the main source of lateral water movement 
toward the depression. In places with shallow water table, the 
capillary rise plays an important role in the accumulation of 
salts on the surface. As a result of capillary action, the soil 
surface is enriched and the salt crust is formed. 
5. Conclusion 
Based on the obtained results from the visual comparison 
between the MSS and TM 
FCC,s we also concluded that visual interpretation of the FCC,s 
recorded in two different dates and field work can be very 
useful for change detection and understanding the factors 
affecting wet land alteration and salt crust formation. By 
studying the effect of micro topography and multitemporal 
analysis with more than two periods, a better understanding of 
human impact on the creation of the shallow water table and 
salt crust formation can be obtained. Using more than two 
images for alteration of the bare land to salt crust, more sound 
conclusion can be obtained. Some destructions of natural 
resources such as alteration of bare land to wet land surface 
and salt crusted area without outlet are irreversible or it is 
difficult to reclaim them. The improper management and the 
use of land unsuitable for development, may bring harm to both 
the natural environment and human lives. A proper 
management of flood irrigation is needed to prevent the 
extension of wet land and salt crust in the Shahidieh Meybod 
area. Otherwise the present condition may lead in the coming 
years to an environmental crisis. This can be a hazard and 
warning. 
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