TM data from 1986 to 2000 covering Shaanxi Province

Gansu Province

Ningxia Hui Autonomous Region

Qinghai Province

Xinjiang Wei Autonomous Region and western Inner Mongolia Autonomous Region were digitally interpreted to determine land use/cover modification.Remote sensing image processing software and Geographic Information System software were used in the research.Analysis methods included image enhancement

pseudo color composite

geometric rectification

mosaic and subset

and graphic database and attribute database establishment.The TM interpretation results for each county in the six regions were added.Three classification levels were adopted for land use/land cover.At the first level six classes were used including cultivated field

forest

grassland

water body

urban and unused land.In 1986

the area of desert

sand field and desertified land across the six regions was 85425467hm2( 26% of the total area)

which was found mostly in Xinjiang

western Inner Mongolia

Qinghai and Gansu.Xinjiang was most severly affected

with 52035232hm2( 32% of the region) affected.In 2000

the area of newly desertified land across the six regions had increased by 1610062hm2 and redesertified land covered 291776hm2

resulting in a net increase of 1318286hm2(0.4% of the total region).Of the six land cover classes

grassland was most severly affected(797081hm2)comprising 50% of the newly desertified land.