By using digital method of remote sensing and geographical information system techniques

TM images of 1996 and 2000 have been interpreted to establish the database of sandy land of two periods in Shaaxi

Gansu

Ningxia and Qinghai Provinces. Through the study practice and analyzing of sandy land databases

the following points can be concluded:In the study area there is as much as 7

910

807hm 2 sandy land in 2000 and more 6

424hm 2 than in 1996. The percentage of sandy land area over the whole area change from 5 733% in 1996 to 5 737% in 2000

and increases 0 004% in 4 years. In different regions

the change of sandy land is various

such as

it increased 0 004% in Shaanxi Province

decreased 0 017% in Gansu Province

decreased 0 479% in Ningxia Region and increased 0 051% in Qinghai Province. And then based on the change types of sandy land

the factors affecting sandy land changes were analyzed according to the situation of different regions.