Landfill site selection is an important environmental issue, which requires consideration of various environmental variables. In this study, seven environmental variables including soil permeability, surface water resources distribution, geographical and geological characteristics alongside with four socio-economical variables including road network, land use pattern, urban and rural populated area were decided as basic criteria to determine the sites appropriate to construct landfill installations for disposal of solid wastes materials in Sanandaj municipality, western Iran. For this purpose two different methods AHP (Analytical Hierarchy Process) and IHWP (Inversion Hierarchical Weight Process) were applied. AHP was applied to carry out pair-wise comparison and also weight assignment using eleven information layers graded from 1 (lowest suitability to 5 (most suitability) as classification of the final map indicated most suitable, moderately suitable and unsuitable places containing 3.77, 2.7 and 93.5 percent of the study area, respectively. For IHWP the same eleven information layers were also weighted according to the comments by the related experts. The exclusion of unsuitable area was conducted using nine exclusionary criteria applied to prepare the restriction map. The map from IHWP method was multiplied by the restriction map and the results was classified to determine the suitable area from landfill site selection. Classification of the final map through IHWP indicated that classes of most suitable, moderately suitable and unsuitable area for landfilling installation occupied 2.2, 4.3 and 93.5 percent of the study area, respectively.
