GIS‐based multi-criteria decision analysis for suitable locations of landfills and protection of peri-urban groundwater catchments: a case study in northeastern Brazil

Groundwater located in peri-urban areas may be impacted by many pollutants from different types of point or diffuse sources. About 40% of Brazil's waste is disposed of inappropriately in open dumps and constitutes a risk of contamination for aquifers. In the metropolitan region of the city of Salvador in northeastern Brazil, approximately 9,800 tons of solid waste are generated daily. This research aimed to delineate areas for the implementation of landfills and protection of peri-urban groundwater in Salvador and other catchments in northeastern Brazil. An integration of Boolean and fuzzy logic was performed using GIS, while the Analytic Hierarchy Process was used in a Multi Criteria Decision Analysis technique to generate the weights of the factors and criteria for the fuzzy model. From this methodology, two preliminary models were generated, one using the Boolean logic and the other the fuzzy logic. The first used restrictive criteria established by Brazilian legislation applied to fifteen factors/themes. In the second model, non-restrictive criteria were applied to eleven factors/themes based on technical knowledge and literature. The integration of the maps and the crossing of the models demonstrates that 6% of the studied areas are classified as highly adequate; 16% as adequate; 8% not suitable; and 70% are areas with total restrictions for locations of landfills and protection of aquifers.