ias first 
hematic, 
used to 
ind out 
lerstand 
ution 
ons and 
tisource 
à into a 
analyse 
re used 
WH 
WY i 
  
5. METHODOLOGY ADOPTED 
This study is based on the analysis of the spatial pastoral 
resources. This makes to an interaction between the physical 
factors. Remote sensing and data base were used to characterise 
the grassland 
degradation. The study region is a semi-arid area of 5000 km? 
situated in the Northwest of Laghouat (Algeria). 
6. RESULTS 
e a land cover map was obtained after treatment of TM images 
196/36 of April 8, 1995. This map shows the different species 
and their level of degradation(see Figure 1). 
Figure 1 : land cover map. 
  
  
  
  
    
three maps of changes were obtained : 1976-1986, 1986- 
1995, 1976-1995; they illustrate an analysis of the evolution 
of grasslands(see Figures 2, 3, 4). 
a vectorial database taking into account the plurithematic and 
multisource data used in a GIS. Although, raster data were 
treated and integrated in the data base. 
  
  
  
  
Legend 
dry culture 
irrigated culture 
sand 
soil 
shadow 
grassland (b) 
‘cours (b) (Nonsa Mucronata & Stipa Tenacissima) | 
grassland (a) 
CCUSIDS (djixupe 1€0ocispme er »upa Perviflara) 
“cours al Stipa Tenacisstma 
Püpa 
   
    
  
  
  
ou 
tanacissiime &rschismue Barbatuis 
grassland en montain 
arr muet. 
grassland (b) 
grassland (a) 
a : fairly degraded 
b : very degraded 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 681