The two periods of Landsat TM/ETM+ images in 1990 and 2000 are used to dynamically monitor the ecological environment of Dingxi

Weiyuan

Longxi

and Tongwei counties. The background data are obtained through screen visual interpretation. The construction

traffic

and mining land increase by 14.97%. The farming land increases by 8.02%. The woodland increases by 11.23%. The bare land

which is suitable for forest and grassland

and floodplain land decrease correspondingly. In the later 10 years

some measurements are carried into execution

for example

small basin integration control

transferring from cultivated land to forestland and grassland

the balance between grass and animal

and rotation grazing and closing of vegetation

which are results of the rationalization of land use and land cover. But there still consists of some problems such as low land use rate

higher ratio of agriculture land

low ratio of stockbreeding land

low ratio of the trees surviving.