summer cold in winter > less rain but concentrate > long 
time Sunny day and more radiation. 
• Vegetation: Grassplot is the leading vegetation,which 
mainly include hilly grassland field, high-cold grassland 
field and high-cold meadow field, hilly grassland field is 
chiefly distributed in the plain of the north bank of 
Qinghai Lake and in the edge of the south hill, and have 
less distribution in the slope to sun with 3200—3500m 
high-cold grassland field and with some plant such as 
precarious. High-cold grassland field principally spread 
in drought slope to sun of the north and middle part 
coteau and small proportion of the hill, with the altitude 
of 3300—3600m, and the vegetation in this region is 
mainly couch grass. Sub-high-cold grassland field chiefly 
distribute in the north of Gangcha and down-sun slope of 
the middle coteau, with 3400—3700 altitude, in the 
region of which vegetation is abundant, but the 
differentiation of the community is not obvious. The 
bottomland of north Molei River is the distribution of 
sub-high-mountain-swamp meadow field with 4400— 
4700m altitude, the arrangement of grassplot is 
unconspicuous with 1.95—12.1cm height of grass and the 
average bestow proportion is 71.5%. Frustex meadow 
field is mainly distributed in the downsun slope of Haixi 
Mountain and north hill with 3300—4500m height above 
sea level, but the arrangement of grassplot is conspicuous. 
• Social and economy: There are four county—gangcha^ 
gonghe > tianjun and haiyan. It has lager population 
consistency, and more developed economy, and which is 
an important pasture base of Qinghai province, and in 
1986 the Qinghai Lake is authorized as the protective 
natural region of state by the State Department. But since 
1950s, due to the change of the climate and the activity of 
the human being’s, the quality of the grass is declined and 
the productivity of stockbreeding is descended in this 
area, and which have grave effect on the sustainable 
development in this area. The status will become worse if 
nothing has been done to the Land Sandy Desertification 
in this area. 
• These characters have much impact of land sand 
desertification on 
2.2 Data 
Land sand desertification is a long-term action, so we elected 
Landsat MSS data collected in Oct, 1973 and ASTER LIB data 
collected in Sep,2003 to do the research. The Advanced 
Spacebome Thermal Emission and Reflection Radiometer 
(ASTER) is an advanced multi spectral imager that was 
launched on board NASA’s Terra spacecraft in December, 
1999. ASTER covers a wide spectral region with 14 bands 
from the visible to the thermal infrared with high spatial, 
spectral and radiometric resolution. An additional backward 
looking near-infrared band provides stereo coverage. The 
spatial resolution varies with wavelength: 15 m in the visible 
and near-infrared (VNIR), 30 m in the short wave infrared 
(SWIR), and 90 m in the thermal infrared (TIR). Each ASTER 
scene covers an area of 60 x 60 km. The ASTER instrument 
produces two types of Level-1 data: Level-1A (LIA) and 
Level-IB (LIB). ASTER LI A data are formally defined as 
reconstructed, unprocessed instrument data at full resolution. 
They consist of the image data, the radiometric coefficients, the 
geometric coefficients and other auxiliary data without 
applying the coefficients to the image data, thus maintaining 
original data values. The LIB data are generated by applying 
these coefficients for radiometric calibration and geometric 
resampling(Mei Anxin, Peng Wanglu, et al,2001, Shunlin 
Liang, 2004, Hu Peng,et al,2002). 
Other than Remote Sensed data , we also elected some climate 
data, topography data, social and economy data, etc. 
2.3 Land Sandy Desertification Classification system 
In order to simplify the classification, this paper classify the 
Land Sandy Desertification to six levels as light, low-grade, 
middle, high-grade, strong and Intensive. Table 1 is the 
classification index of the Land Sandy Desertification. 
Table 1 Classification Index of Sandy Desertification 
Grade 
Surface form 
Vegetation 
Overcast ratio 
1 light 
Fastness dene, sandlot and 
sand beach 
>70% 
2 low-grade 
Fastness dene, half-fastness 
sandlot and sand beach 
70-50% 
3 middle 
half-fastness dene and 
sandlot 
50-30% 
4 high-grade 
half-fastness dene, flowing 
sandlot and sand beach 
30-10% 
5 strong 
flowing sandlot and sand 
beach 
<10% 
6 intensive 
Large-area flowing sandlot 
and sand beach 
<5% 
2.4 process flowchart 
Figure 2 is the process flowchart used in the paper. We use 
false color image of ASTER 3N21 and false color image of 
MSS 754 for Unsupervised Classification, then with the aid of 
NDVI Retrieval result, Climate data, Topography data, Social 
and Economy data to do the Land Sandy Classification. 
Figure 2. Process flowchart 
3 RESULTS 
3.1 Land Sandy Desertification in 1973 and 2000 of 
Qinghai Lake Area. 
Figure 3 and Figure 4 are the spatial change of Land Sandy 
Desertification in 1973 and 2000 in Qinghai Lake Area.