Assessing Land Suitability for Sanitary Landfill Siting Using GIS–MCDA in Zamboanga City, Philippines

Zamboanga City is one of the fastest-growing cities in the Philippines. With its potential for physical and environmental development, it is currently facing increasing air and land pollution as major environmental concerns. The city is also nearing the full capacity of its existing sanitary landfill, making it necessary to identify suitable areas for future municipal solid waste (MSW) disposal. This study aims to assess land suitability for sanitary landfill site selection using Geographic Information System (GIS)-based Multi-Criteria Decision Analysis (MCDA). Selecting a suitable landfill site is a complex process due to the need to consider multiple environmental, economic, and social factors. In this study, several criteria were evaluated in accordance with NSWMC Resolution No. 64, Series of 2013, including groundwater and surface water, geology, soil properties, built-up areas, flood vulnerability, fault lines, land use, and road networks. GIS was used to manage and process the spatial data, while the Analytical Hierarchy Process (AHP) was applied to determine the relative importance of each criterion through pairwise comparison. These were then integrated using weighted overlay analysis to generate a land suitability map. The results show that approximately 1.31% of the study area is classified as most suitable, while 16.12% is suitable for landfill development. Two potential landfill sites were identified after considering additional factors such as minimum required area, buffer distances from residential areas, and accessibility to major roads. The findings indicate that improper landfill siting may lead to negative environmental, economic, and ecological impacts, highlighting the importance of systematic and evidence-based site selection for sustainable waste management planning.