Data-driven landfill suitability mapping in Lagos State using GIS-based multi-criteria decision making

Abstract

Careful selection of landfill sites is essential because improper dumping of wastes can negatively impact health and degrade the environment. Therefore, this research presents a Geographic Information System based—Fuzzy Analytic Hierarchy Process multicriteria decision-making approach for landfill zonation in Lagos State, Nigeria. Due to the rapid urbanisation leading to urban expansion and conversion of the landfills to built-up areas in Lagos State, the functioning landfills have been reduced. After a comprehensive literature review, this study considers nine factors: slope, elevation, land use and land cover, lithology, soil type, Normalised Difference Vegetation Index, the distances to roads, distance to settlements, and distance to water bodies. From the decision matrix, the distance to water bodies, distance to roads, distance to settlements, and land use and land (LULC) cover were ranked with percentage weights of 22%, 19%, 17% and 11%, respectively. Afterwards, potential landfill sites were mapped and classified into five classes: very low (626.48 km2, 16.66%), low (1277.56 km2, 33.97%), moderate (1227.97 km2, 32.65%), high (500.52 km2, 13.31%), and very high (128.13 km2, 3.41%). The low and moderate suitability classes have the highest areal coverage due to the state's increased population and urbanisation. A large percentage of the high to very high suitability classes are located in Epe, Ikorodu, and Ibeju-Lekki local government areas (LGAs) which have lower urbanisation levels compared to most of the other LGAs. Therefore, governments and stakeholders should explore these areas for siting of landfills.