drying

drinking

wasting

watering

Landsat images

vegetation 

Landsat

sand

Landsat images are the first and foremost inventions of the last 25 years because they help us understand the process and problems of desertification

Remote-sensing systems, land-monitoring networks, and global data bases of field observations are what evidently caused the problem of desertification.

Such global monitoring systems are necessary to better understand desertification because no other system, network or database could be less accurate than Landsat images.

Landsat images may help understand the processes and problems of desertication, but more remote-sensing systems, networks and databases are needed before the matter could be properly and completely understood.

removing shrubs and trees planted within the grids

covering the dunes with large boulders or petroleum to interrupt the wind regime

placing vegetation inside the grids

by placing straw grids

desertification

transition zones

productive land

local climate

refusal

agreement

denial

dissension

flat

humid

dry

boring

they have stable and delicately imbalanced ecosystems with a variety of microclimates 

they have unstable and carefully balanced ecosystems with a variety of microclimates

they have unstable ecosystems with a variety of macroclimates

they have carefully balanced ecosystems with a variety of microclimates

a flat area of desert covered with wind-swept sand with little or no vegetative cover

large sand areas that are now inactive to stablilized vegetation

large sand areas that are still active due to stabilized vegetation

a flat area of desert coverred with little or no vegetative cover

Great deserts were created by natural processes over long time intervals, and their development has been independent of human influence

Great deserts were created by natural processes over long time intervals

Great deserts were created by natural processes and human activities

Great deserts have grown and shrunk with the help of human intervention and other natural processes