GIS- and MCD-based suitability assessment for optimized location of solid waste landfills in Dar es Salaam, Tanzania

Despite recent advancements in waste management technologies, landfills remain the dominant approach for the final disposal of solid waste (SW) around the world. However, landfills are associated with adverse environmental and health-related impacts. This study is primarily applied to Dar es Salaam, a city in the East African region that has failed to follow appropriate approaches for site selection and that the methods used to select the current sites are manually operated. The study used a geographical information system (GIS) combined with multicriteria decision analysis (MCDA) to objectively determine the optimal landfill sites. A comprehensive list of assessment criteria was examined through a computerized site selection procedure based on GIS to analyze the ground that was surveyed and to remotely obtain data. Analytical hierarchy process (AHP)-one of the best MCDA approaches-was used to assign relative weight and evaluate each criterion. Finally, the study computed site suitability indices (SSIs), which aids in the identification of site suitability levels (SSLs) for the entire region. The final suitability map produced by overlaying the criteria map layers showed that a large part of the study area (60.92%) was completely unsuitable for landfill siting. The remaining areas consisted of land with varying suitability level, which were grouped into four classes: very low (30.92%), low (2.05%), moderate (5.65%), and high (0.46). To this end, only the high suitability class (0.46%) was of acceptable suitability levels (ASLs) (SSI ≥ 2.0). From the numerous identified sites with ASL, only three sites were suggested. Due to concerns regarding the lifespan and environment-related risks associated with these suggested sites, there is a need to further study new environmentally friendly techniques, considering the importance of circular economy agenda of waste to resource/energy for sustainable solid waste management.