A Combined GIS-AHP Approach for Sanitary Landfill Selection in Tangub City, Philippines

Abstract

Solid waste management remains a major challenge in the Philippines, particularly due to the limited availability of sanitary landfills that meet environmental and regulatory standards. According to recent records, 210 local government units (LGUs) still lack access to sanitary landfill facilities. This study applies an integrated Geographic Information System (GIS) and Analytic Hierarchy Process (AHP) approach to identify suitable sanitary landfill sites in Tangub City, Southern Philippines. GIS-based spatial analysis excluded environmentally, and socially constrained areas based on proximity to built-up areas and water bodies, ecological sensitivity, elevation, slope, road accessibility, and minimum land area requirements. From the city’s total land area of approximately 17,899.8 hectares, only 230 hectares (1.28%) were identified as suitable, yielding ten candidate sites. These sites were evaluated using AHP, with six criteria weighed based on expert judgment. Proximity to water bodies (0.38) and built-up areas (0.23) received the highest weights. The results indicate that San Vicente achieved the highest overall suitability score (0.234), followed by Capalaran (0.124) and Bintana (0.116). Consistency ratios for all pairwise comparisons were within acceptable limits (CR < 0.10), confirming the reliability of expert judgments. Sensitivity analysis further demonstrated that San Vicente remained the top-ranked site under most weighting scenarios, indicating strong robustness. The findings provide a data-driven and replicable framework to support sustainable landfill siting decisions for Tangub City and similar LGUs in the Philippines.