Geospatial Analysis of Lagos State Landfill Site Suitability and Multi-Criteria Spatial Decision Support System

Landfill siting is an extremely complex task, mainly because of the process and strict regulations engrossed. This study determined suitability of Lagos State landfill sites by combining geographic information system (GIS) and multicriteria decision-making method (MCDM) known as analytic hierarchy process (AHP). Global Positioning System (GPS) receiver was used to acquire x, y coordinates of the existing landfills. These were interpolated on the administrative map of the study area to show their spatial pattern. Environmental Protection Agency (EPA) landfill site selection criteria were afterward used to identify set standards and requirements for optimum landfill site. Landsat 7 ETM+2012 was utilized to analyze various land uses around the existing landfills in the study area while ASTER DEM was used to assess the elevation of the study site. The imageries were enhanced and geo-referenced for correct locational identity. Landsat imagery was however, classified into different land uses using supervised classification algorithm. The extracted spatial data were prepared in ArcMap 10.5, processed with AHP weighting/ranking operation and finally produced a suitability map, which was labeled as highly suitable, moderately suitable, less suitable and unsuitable. The results revealed that landfills in Lagos State were no longer suitable in their existing locations. Besides, only 0.001% of the total land area of the study area was identified as highly suitable, 0.119% as moderately suitable and 99.4% unsuitable for landfill site. In conclusion, the study generated a synthesis of knowledge valuable for the planners and stakeholders in the management of urban waste.