GIS‐based multi-criteria decision analysis for landfill allocation in a tropical metropolitan region

The increase of the urban population in the world and the associated economic expansion have accelerated municipal solid waste (MSW) production. About 40% of the world's waste is disposed of inappropriately in open dumps and/or only partially controlled landfills. Many types of waste are mixed and disposed without treatment in illegal dumpsites or non-sanitary landfills, especially in developing countries such as Brazil. This research aims to identify areas for the implementation of landfills in the tropical climate of the Metropolitan Region of Salvador (MRS), Brazil, which generates approximately 4900 tons of MSW per day. In a first step, geographic information system (GIS) is used to apply Boolean logic to 15 restrictive criteria based on Brazilian legislation. In a second step, locations found to be legally appropriate are ranked with the analytic hierarchy process (AHP) in a multi-criteria decision approach using 11 non-restrictive criteria based on technical knowledge and literature. Results show that 6% of the areas are classified as highly suitable, 16% as suitable, 9% not suitable, and 69% with legal restrictions. The result of this study serves as a guide for suitably siting landfills in the MRS and similar regions in the world, reducing costs and biased assessments potentially implied by empirical methods.