Proposal for a low-cost methodology for selecting areas to locate a sanitary landfill using GIS and multi-criteria analysis: case study in São Paulo, Brazil

Abstract

The municipalities in the region of Araras/São Paulo present difficulties in the adequate disposal of waste, as they do not have resources to implement individual solutions, and the existing landfills in the region have a relatively short useful life. In line with the guidelines of the National Policy on Solid Waste (PNRS), which encourages consortium solutions to optimize infrastructure and to reduce costs, an intermunicipal consortium involving Araras and adjacent municipalities was proposed and the need for a minimum area of 40 hectares for installing a new intermunicipal sanitary landfill (ISL) was estimated. This study thus presents a low-cost methodology that integrates free geographic information systems (GIS) tools with multi-criteria decision analysis (MCDA) techniques to identify areas suitable for implementing the ISL. The approach was structured into three main stages: (i) application of restrictive criteria to exclude unsuitable areas; (ii) weighting of areas previously classified as suitable by elaborating four scenarios (environmental, economic, social, and balanced); and (iii) refinement of the pre-selected areas based on additional spatial and contextual criteria. Of the 33.5% of the territory considered suitable, the balanced scenario (scenario 4) highlighted 21.17% of the area as “Excellent,” allowing the pre-selection of ten locations, of which three were prioritized after refinement, culminating in the selection of Area 5 as the most favorable. The methodology proved to be effective, efficient, and innovative, by offering an accessible, adaptable, and technically robust structure for locating projects with high potential for environmental impact. Its differential lies in the flexibility provided by the creation of multiple scenarios, allowing managers to evaluate alternatives based on different priorities and to opt for more sustainable approaches. The ease of application of the techniques involved, combined with the possibility of prioritizing the criteria and replicability in other regions, reinforces the potential of this approach as a strategic tool in territorial planning and integrated waste management.