Choosing a suitable location for the disposal of municipal solid waste is an important environmental problem. Thus, locating a municipal solid waste landfill has been very important. Leachate from the solid waste landfill causes the contamination of groundwater. However, the process is complicated and is based on qualitative and quantitative criteria. Therefore, in this paper, a hybrid approach for determining the optimal location of a municipal solid waste landfill has been presented. Additionally, the present study attempts to evaluate the potential of aquifer contamination vulnerability on the proposed landfill sites using a DRASTIC model of Plain Zanjan and provide a zoning map of vulnerable areas. In this study, the DRASTIC model for aquifer vulnerability mapping is used. This model consists of seven hydrogeological parameters effective in contaminating the aquifer. The parameters appear in the GIS software as seven layers on which the analysis is performed. Considering the map of aquifer vulnerability and with regard to the potential aquifer contamination at various areas, it is possible to determine a suitable site for the landfill. At present, about 49.03% of the aquifers are in average vulnerability situation; by considering them, a suitable site for the landfill can be determined. Accordingly, the considered criteria were determined by AHP method; the weights of the layers were determined, and then the appropriate places were classified into three classes, high, moderate or low, using GIS software. Finally, zones located in the high classes were selected as the best locations for waste disposal by the PRPMOTHEE method, by taking into account the scientific limitations and conditions of the area. The results showed that proposed methods in this paper can be suitable to determine appropriate option for waste disposal. In the future, there can be a lot of studies for modeling to choose a suitable landfill due to some soil characteristics and applying other models of pollution to groundwater in the region.

Abstract:Groundwater pollution caused by human activity is a serious environmental problem in cities.Pollution vulnerability assessment of groundwater resources provides information on how to protect areas vulnerable to pollution. The present study is a detailed investigation of the potential for groundwater contamination through construction of a vulnerability map for the study aquifer in Zanjan plain. The parameters used in the DRASTIC model are depth-to-water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity. The overlying index, GIS and AHP were used with the modified DRASTIC model to evaluate the vulnerability of the alluvial Zanjan aquifer to nitrates. AHP was used to determine the rate coefficient of each parameter. The correlation coefficients were produced by comparing the vulnerability index with the nitrate concentrations in the groundwater. The results show that the DRASTIC index values for the study area ranged from 82 to 186 and were divided into low, medium, and high vulnerability classes. GIS was found to provide an efficient environment for such analyses. The DRASTIC aquifer vulnerability map indicates the dominance of the medium vulnerability class in the most parts of the study area (49.033%). The high correlation coefficient for the modified DRASTIC index (0.92) and nitrate layer than for the standard DRASTIC model (0.74) suggests that the actual condition in the study area can be better explained by the modified DRASTIC model.