The diachronic land use analysis, performed by processing the sensor data, is based on the 10-and 30-yearchange maps. The dynamics of the vegetation is followed by the application of the NDVI. The gradual and regressive changes in the components of land use reached the rates of 44.78% and -29.21% respectively. The most reduced surfaces are the forest massifs, the steppe area and to a lesser extent the waters of the saline surfaces (dayet). Cereal crops, urban and mineral areas, on the other hand, have increased in area to the detriment of the natural plant cover. The stability of the studied area recorded only a rate of 26.01%. This rate represented only ¼ of the area of the south of Tlemcen region.

Modes of occupation of the soil of the steppe area of the department of Sidi Bel Abbes (Western Algeria) know lots of mutations during the period 1987/2013; compromising the future of pastoral activity. This dissection based on supervised classification TSAVI values (Transformed Soil Adjusted Vegetation Index) using images of remote sensing of average spatial resolution of type Landsat-TM 5 and 8. The determination of the state of occupation of the ground and validation of remote sensing map shows that the status of the halophytic/psammophytic steppes and the Matorrals are detected in 38.38 % and 55,71 % of cases, respectively. On the other hand, the steppes chamaephytic mark -9,81 % regression only, agricultural land -24,51 %, and -46,24 % dense vegetation are correctly mapped. The sensing medium resolution is therefore, in the light of these figures, a management tool of the steppe field relevant and effective, which, in addition, allows enriching the field for a proper plan for the fight against desertification.

The development of space technology has allowed a better understanding and effective use of water resources through the use of Digital Terrain Models (DTM) Mapping the river system from DTM has two objectives, namely identifying first topography descriptors like hills, ridges and valleys of watersheds and second hydrological parameters to map areas of runoff recovery for a more efficient development and also a better representation of the actual land occupation. Our work is part of a methodological approach to satellite imagery processing and mapping of topographic and hydrographic parameters of watersheds. Thus, from DTM one was able to extract the full river system of the region. The results show a remarkable evolution of human activities and especially in areas of high water recovery capacity.