The appropriate site selection is an important issue for waste management activities in developing countries. An inappropriate landfill site may cause negative environmental, economic, and ecological impacts. Sanandaj city, western Iran, with a population of 370, 000 people faces daily production of 330 tons of solid wastes. Current landfill site of the city has caused environmental problems, while losing its capacity. This study attempted to determine appropriate landfill sites for municipal solid wastes in Sanandaj city through combination of Geographic Information System (GIS) and Multi-Criteria Decision Making (MCDM) techniques. For this purpose, nine information layers were weighted according to Analytic Hierarchy Process (AHP) and Inversion Hierarchical Weight Process (IHWP) methods. The final suitability maps for a landfill construction in both methods obtained by using overlay function and seven exclusionary criteria, which were used to prepare the restriction map. The result of this study showed that IHWP method increased the accuracy of the final decision for identifying best quality landfill sites and provided better results in comparison with AHP. Finally, an area with the extent of 87 ha, located approximately 5 km north-west of the Sanandaj, was identified as priority number one to establish a landfill site.
