Suitable landfill site selection using GIS-based multi-criteria decision analysis and evaluation in Robe town, Ethiopia

Solid waste management is a serious problem in most cities of the world due to rapid urban expansion and it causes increasing solid waste generation. The practice of solid waste management in Robe town was very poor and it is one of the chronic problems of the town. Therefore, the town needs a suitable landfill site to properly manage solid wastes and mitigate its impacts on public health and environment. The purpose of the study is to identify suitable landfill sites in Robe town, Ethiopia, that is socially and environmentally acceptable, and economically feasible by applying geographic information system and multi-criteria decision analysis and evaluation techniques. This study was based on factor criteria thematic layers of land-use and land-cover types, groundwater depth, lineament, soil permeability, river, water pipelines, slope, main and secondary roads, and constraints thematic maps of boreholes, built-up areas, and green areas. The analytical hierarchy process pair-wise comparison model was used to compute the weight of criteria. The weighted linear combination model was also used to combine different criteria weight and produce a suitable landfill site map. Landfill site suitability map was prepared by overlaying different criteria and suitability ranks were assigned as unsuitable, low suitable, moderately suitable, highly suitable and very highly suitable. The result of the study shows that 41.02 km(2)(651.12%) of the area was unsuitable, 16.27 km(2)(20.28%) was low suitable, 10.53 km(2)(13.12%) was moderately suitable, 7.54 km(2)(9.40%) was highly suitable and 4.88 km(2)(6.08) was very highly suitable. From highly and very highly suitable sites, 7 candidate landfill sites were selected and evaluated in terms of area of the site, distance to nearby boreholes, built-up areas, green areas and distance from the center of the town to choose the most suitable site. According to the result of the study, landfill site 6 was the most suitable followed by landfill site 5 while landfill site 2 was the least suitable. The result also shows that selected suitable sites are expected to be friendly to the environment and the societies. Therefore, to have a sound environment and improve public safety, the town should need a landfill site and implement integrated solid waste management.