Fuzzy MCDA and GIS application to sitting landfill with emphasis on wind properties and fuzzy operators’ comparison in the Gharehchai basin, Hamedan province, Iran

The study of landfill sites is one of the most important subjects in engineering geology. The landfill site selection involves various elements such as engineering, science, and politics. In this case study, landfill site selection was performed by developing a multi-criteria decision analysis (MCDA) method in the Gharehchai basin, Hamedan province, west of Iran. Fuzzy membership functions (FMFs) resultant from GIS analysis are base of this method. Twelve different criteria including surface water, water table, geologic unit permeability, soil type, slope, distance to faults and sinkholes, main roads, residential areas, distance from water well and Qanat, Normalized Difference Vegetation Index (NDVI), wind speed and direction and distance from special land use were used to landfill site selection. The fuzzy-based MCDA technique can help the decision-makers to understand the complete estimation process and make a better decision to select a proper site for landfills. FMFs were used to standardize the criteria to be applied in the development of a landfill site suitability map. Lastly, a suitability map was prepared by fuzzy overlay analyses (Gamma operator), and appropriate areas were recognized and checked. The results comparison indicated that among the Fuzzy Gamma values, the value 0, gives a more conservative area of the most suitable class that is much more limited than the other Fuzzy Gamma values. The results by Fuzzy Gamma value equal to 0 shows that 97.51% of the study area is unsuitable, 1.91% least suitable, 0.54% moderately suitable and 0.15% is most suitable for landfill construction.