Geo-spatial Technique Combined With AHP, SRS, and RSW Methods for Suitability Analysis of Landfill Site in Durgapur Municipal Corporation


 Durgapur, an industrial city, is the second and third-largest city in West Bengal in terms of population and area respectively. The city is suffering from an enormous generation of waste and improper waste management. The wastes are dumped in an unscientific and unplanned way, negatively impacting the environment and public health. Hence, the National Green Tribunal has advised the city planners to find new landfill sites following the Central Pollution Control Board's guidance. This paper focuses on the new landfill site selection of Durgapur city using the Multi-criteria Decision Making (MCDM) methods with Geographic Information System (GIS). The methodologies used for the site selection processes are GIS (for mapping the 14 criteria and overlay analysis) and MCDM methods: Analytical Hierarchy Process, Straight Rank Sum Method, and Ratio Scale Weighting Method (to derive the weights). Finally, the five landfill sites are selected after calculating the change detection.


Introduction
The suitability analysis requires spatial data with respect to sitting rules, regulations, factors, and 142 constraints for landfill site. The Multi-criteria Decision Making (MCDM), a decision support 143 system, calculates the relative weights from the criteria. Furthermore, the relative weights are 144 applied on the map layer in GIS to determine the suitable area for landfill sites. The MCDM 145 methods, combined with GIS, pave a significant path for the researcher to find out a suitable site 146 for landfill (Malczewski 2006, Gorsevski et al. 2012). Therefore, this combination is a well-147 known tool in detecting suitable landfill sites (Kao et al.1996; Kontos et al. 2005; Delgado et al.  It is the second planned city in India after Chandigarh. Geographically Durgapur is "Rurh of 168 Bengal" because the western side of the city is full of resources (coal and iron ore); 169 consequently, heavy industries are concentrated in its surroundings. This city is also known as    193 Toposheet no: F45D, and the GPS are used for coordinating the existing dumping ground.     Groundwater potential: 223 The input layer of the groundwater potential map is prepared through the District Planning Map 224 Series. We obtain two zones of potential: one 1-5 yeild in litre/sec and the other one 5-10 yeild in 225 litre/sec shown in Fig.4a. The aforesaid two zones have given rating 7 and 3 respectively. We 226 have given the lowest (highest) yield of groundwater potential area the highest (lowest) rating.

227
The groundwater contaminated from the pollutants of landfill depends upon the soil porosity and 228 the permeability of the rock. Here, we only study the potential layers of groundwater.  249 The topography and geology are considered as the essential appraisals to control leachate,   Table 1). interval for airport, and then converted into Raster layer (Fig 6). According to CPHEEO 2000, 297 landfills cannot be suitable within 200m buffer zone on both sides of road and railway network.

Criteria for topography and geology
The four layers (highway, major road, railway, and airport) are reclassified in GIS and the 299 corresponding rating of the buffer zones are given in Table 1.   348 Malczewski, in 1999, has described the straight rank sum method. It is a simple ranking .

Straight Rank Sum Method (SRS)
(1) 356 The calculated value of relative weights of 13 criteria are shown in Table 2 357 358 The Ratio Scale Weighting Method is also applied in this study. The weights of the criteria are  Table2    produced the pair wise comparison matrix. Relative weight, derived from the pair-wise comparison matrix for each criterion, allows the decision makers to choose the best criteria. In 382 the next paragraph, we elaborately discuss the methodology to construct the matrix C.

383
Let C is a matrix of dimension × with elements , which satisfies the following condition:  Table 4 where, upper row is the random matrix order and lower row (RI) is the 393 corresponding index of consistency for random judgment.  12 1.24 1.32 1.41 1.45 1.49 1.51 1.48 1.56 1.57 1 proportional to the degree of consistency of the judgments, i.e., lower values of CR are 397 indicating more consistent judgments (Setiawan et al., 2014). In this study, adopting 14 = 398 1.57, the calculated value of CR is 0.072< 0.1 = Acceptable, which further implies that there is 399 reasonable consistency level in the pair wise comparison, and it is elaborately shown in Table 5.

404
The weighted overlay analysis is the most applied approach to solve multi-criteria problems in 405 GIS. In order to draw the final suitable maps from the multi-criteria, we use the weighted overlay  Table 6.  Fig. 9). The landfill sites are always selected from 453 the most suitable and the suitable areas in the matching pixel regions. All the methods are 454 overlaid to determine the intersecting area within the map (Fig. 10a) The author thanks Anupam Ghosh for several discussions and help in writing the paper. The

Author Contribution 490
It is a single author paper.