Evaluation of spatial restriction for the urban sanitary landfill along the Mazandaran province using GIS and analytical hierarchy process

Introduction: Today, solid waste management is an important problem for urban planners all over the world. The landfill, which is a site for the safe disposal of waste materials by burial, considered to be the core of an integrated waste management strategy in modern cities, when it is accompanied by other methods. Selecting a suitable site for landfilling is the first and most important phase in the process of waste disposal. Geospatial Information Systems (GIS) became a common tool for the selection of landfill sites. In this research by integrating spatial information systems and a multi-criteria decision-making model, spatial limitations for siting sanitary landfills along the province of Mazandaran were evaluated based on the regulatory compliance mentioned by the Iranian Department of Environment.
Material and methods: Municipal solid waste disposal is one of the major problems of the urban environment in almost all northern states of Iran, especially in Mazandaran Province. In this paper, using the analytical hierarchy process a spatial information system has been developed for siting urban waste burial landfills in Mazandaran province. In this study, ArcGIS 10.4.1 software was used to create an information database for spatial analysis and integration of map layers. The AHP model and Expert choice software were also used to compute the weight of criteria.
Results and discussion: In this study, first, according to the regulatory requirements of the Iranian Department of Environment, the effective factors for siting urban landfills were extracted. These criteria are slope, distance from fault, flood plain, distance from the sea, distance from rivers, distance from lakes and wetlands, distance from groundwater wells, groundwater depth, distance from the protected areas, distance from urban areas, distance from rural areas, distance from educational and medical centers, distance from historical and ancient centers, distance from local and international airports, distance from industries and also having access to roads. Considering the elimination criteria and by classification and scoring them, maps of the layer of each criterion were produced in the GIS system. As the role of each criterion is different, at the next step, the relative weights of criteria were calculated using AHP and Expert Choice. Finally, by integrating the map layers of each criterion and by deleting layers of limitation, the suitable areas have been classified into three categories. The results show that 16156 KM2 of Mazandaran province (about 68 percent of the total area) is forbidden for any landfilling based on the national regulations of DOE and only 32 percent of the total area has the initial conditions for any disposal. The initial candidate landfill sites were separated into 3 categories, high suitability, moderate suitability and low suitability. So the 2405 KM2 of the province's area has low suitability, 4914 KM2 with moderate suitability and 281 KM2 has high suitability conditions.
Conclusion: The comparison of results show that only 2 percent of the province has essentially the optimal conditions for proper landfilling and Mazandaran province is a region with strict restriction from this aspect. This study shows that the combination of GIS and AHP methods for application of regulatory requirements for limitation zone and the priority setting criteria can be considered as a suitable approach for siting urban landfills.