Landfill Sites Selection Using Analytical Hierarchy Process and Ratio Scale Weighting: Case Study of Al-Mahawil, Babylon, Iraq

Selecting a landfill site is an optimal solution for the disposal of solid waste in Al-Mahawil Qadhaa, both to fulfill the environmental and scientific requirements, and to comply with regulations and restrictions in this Qadhaa. Presently, there is no landfill site in the area that meets the scientific site selection criteria. Therefore, in this study, two methods of multi-criteria decision-making and Geographic Information System (GIS) were used to produce a map of candidate sites for landfill. Fifteen criteria were entered within GIS: groundwater depth, rivers, soil types; agriculture lands use, land use, elevation, slope, gas pipelines, oil pipelines, power lines, roads, railways, urban centers, villages and archaeological sites. The Analytical Hierarchy Process (AHP) is the first method that was applied to derive criteria weightings using the matrix of pair-wise comparisons. The second method was the Ratio Scale Weighting (RSW), which is based on experts’ opinion, in order to identify the criteria weightings by giving a ratio score value for each criterion relative to the other criteria. Accuracy assessment (Kappa and Overall Assessment) methods were used to compare the two raster maps which resulted from the two models, and to determine the percentage value of matching pixels for the two maps. Two suitable candidate sites for landfill were identified that satisfy the requirements with an area of 2.218 km2 - 2.950 km2 in order to accommodate the solid waste generated from the Qadhaa in the period 2020 to 2030.