ASSESSMENT OF SUITABLE LANDFILL SITE USING GEOSPATIAL TECHNIQUES: A CASE STUDY OF RAIPUR URBAN REGION, CHHATTISGARH, INDIA

Currently, the solid waste management work of Raipur is being done in a completely traditional way, which is very expensive and time consuming. The site selection method using Geospatial techniques can function as a decision support tool for enhanced efficient and effective management of municipal solid waste. This Study’s aim was to develop landfill siting by crossing major barriers such as political, economic and environmental pressures for the execution of a suitable site criteria by employing combination of geospatial technique and Weighted Linear Combination (WLC) of Multi-Criteria Decision Analysis (MCDA) in Raipur urban area. The preliminary step of the methodology was geospatial operation and Study that disqualified all areas unsuitable for landfill siting. The insularity of suitable criteria for landfill site was generated based on published information on solid waste management, existing laws and regulatory necessities, as well as the existing local conditions. The different suitability criteria considered are soil, land use land cover, digital elevation model (DEM), surface waters, transport network, lithology and geological structures. Criteria were mapped using the geospatial technique; each criterion was identified and weighted by score for overlay to create suitability maps using GIS. The final results showed that there are more locations for landfills for Raipur urban area. In the present Study there are sporadic areas identified as suitable sites for landfill location. In the site suitability analysis 74.79% area found not suitable for landfill siting, 20.93% least suitable and 3.25% moderate suitable. Out of the remaining area, 1.03% area is found most suitable.


STUDY AREA
Raipur Urban Region including New (Nava) Raipur area lies approximately 21°02'50'' to 21°19'50'' north latitude and 81°32'00'' to 81°53'50'' east longitude, location map is shown in Figure 1. Raipur Urban Region including New Raipur area is at an altitude of 298.15 m meters above sea level and covers an area of approximately 636.665 km2 with total Population (Census 2011) -1,123,558 inhabitants and Density -6463/km2. The urban area is bounded by geographical features; the Mahanadi river in the east, the Kharun in the west, Mahanadi Canal in the north, and Khilora Nala in the south of the urban boundary.

METHODOLOGY
As mentioned earlier, there are no specific criteria for selecting solid waste disposal sites in Raipur urban area. The criteria used in this study were based on criteria derived from literature review with adjustments to local desired priorities and requirements. Six suitability criteria: distance from transport networks, distance from Drainage network and water body, distance from faults and lithological conditions, soil characteristic, landuse landcover condition and slope, were used in this study. Transport network, Drainage and surface water bodies, geological structure and LULC data were delineated and updated from Cartosat 1 the year of 2018 having 2.5 m resolution of the Study area. The weighted linear combination (WLC) technique is a decision rule for deriving composite maps using GIS. The methodology adopted for the Study is divided into two subgroups: i) site selection criteria using Weighted Linear Combination (WLC) and ii) GIS overlay analysis(Al-Hanbali et al., 2011; Moeinaddini et al., 2010;Saeed et al., 2003;Salmon Mahini and Gholamalifard, 2006). Ancillary data were collected, maneuvered, analyzed, and overlay in the GIS environment to determine the suitable landfill sites. The methodology adopted for the present Study is shown in the flowchart (Figure 3).
Digital Elevation Model (CartoDEM 30*30 m resolution, (Source: https://bhuvanapp3.nrsc. gov.in) was used to derive slope. These criteria were divided into constraint and factor criteria where the former represents unacceptable areas, latter represented the acceptable areas for landfill siting. GIS buffering was used to screen out Amit P Multaniya, Sanju Verma, and M. K Beg International Journal of Research -GRANTHAALAYAH 135 unsuitable areas based on the defined criteria. All the constraint criterion maps were overlaid to produce the final factor map. Seven important assessment criteria were identified i.e. soil texture, land use land cover, slope, surface waters, transport network, lithology, and geological structures in the Study area.  Suitable criteria for landfill site selection in Raipur region, Chhattisgarh, India were generated based information published on landfill criteria as well as the prevailing local conditions (Central Public Health & Environmental Engineering Organization-CPHEEO Manual). Suitable areas were identified from Suitable Site maps and classified of highly suitable, moderately suitable, least suitable and not suitable and for being used as site locations. This was done by weighting processes where each map layer was both internally weighted based on the minimum and maximum distance to features (environmental judgment) and externally weighted using Multi-Criteria Decision Analysis (MCDA) based on its relative importance to the waste disposal problem (Fides K. Kirimi, 2014).

DRAINAGE AND SURFACE WATER SOURCE
Drainage delineated from Survey of India toposheets 64G11 & 64G12 and updated from Cartosta-1 imagery and created various buffer zones for assigning the influence weight in GIS environment. Drainage network map of the Study area is shown in Figure 4.

TRANSPORT NETWORK
Accessibility to landfill location must be close to road network for effortless movement and reducing comparative costs of waste material. Road and Rail network delineated from Cartosat-1 imagery and Survey of India toposheets no 64G11 & 64G12 and created various buffer zones. Transport network map of the Study area is shown in Figure 5.

LITHOLOGY AND STRUCTURE
The lithology of the Study area constitutes Arenite and Shale having low permeability due to low degree of weathering and fracture that's covers the major portion of the Study area. Other major rock type observed was Alluvium and Laterite (District Resource Map, Raipur). It is also characterized by the occurrence of geological structures within the different rock type of Study area and its great importance in landfill site investigation. Geology map of the Study area is shown in Figure 6.     Malczewski, 2006Malczewski, , 2000. It is one of the most often used decision models in GIS. The method is often applied in land use/suitability analysis, site selection, and resource evaluation problems. The primary reason for its popularity is that the method is very easy to implement within the GIS environment using map algebra operations and cartographic modeling. The method is also easy-to-understand and intuitively appealing to decision makers. WLC can be operationalized using any GIS system having overlay capabilities. The overlay techniques allow the attribute map layers (input maps) to be aggregated in order to determine the composite map layer (output map). Six suitability criteria: distance from transport networks, distance from Drainage network and water body, distance from faults and lithological conditions, soil characteristic, landuse landcover condition and slope, has been taken for Landfill suitability Study. There were many steps that were performed in GIS in order to get the final required criterion in this study (e.g., Buffer, Clip, Extract, Overlay, Proximity, Convert, Reclassify and Map Algebra, etc.). Each criterion was reclassified, and then given ranking, to comply with a specific scheme. Then, a final composite map was produced using WLC (Al-Hanbali et al., 2011; Eastman et al., 1995;Hopkins, 1977;Malczewski, 2006). The weights and scores were assigned after several discussions with the local experts, and decision makers, in addition to the previous knowledge of the study area. As a general rule, it was decided to give higher weightings to factors that affect directly on the community such as distance from urban areas, distance from agricultural lands, and distance from the faults, whereas the other factors, which have lower effects on the community or can be adjusted by engineering processes, were assigned lower weightings  Table 2.

ESTABLISHING THE THEME WEIGHTS AND CRITERIA SCORE
As indicated above, the most prevalent procedure for multi criteria evaluation is the weighted linear combination. The literature review was used to identify inconsistencies and to develop the best fit weights, the Weight linear combination comparison analysis was established by equation (1) with a weighted linear combination, factors are combined by applying a weight to each followed by a summation of the results to yield a suitability map: i.e.
Where S is the suitability, wi is a weighting of factor i, and xi is the criterion score of factor i.
Assessment of Suitable Landfill Site Using Geospatial Techniques: A Case Study of Raipur Urban Region, Chhattisgarh, India Once the value was established, the module Multi-Criteria Decision Analysis (MCDA) was used to combine the factors and constraints in the form of a weighted linear combination. Score assigned for each objective are geographically coherent and meaningful in terms of the criteria specified. The procedure is optimized for speed and has the effect of multiplying each criterion by its weight, adding the results, and then successfully multiplying the result by each of the constraints.  Figure 10: Single-Criteria overlay suitability trend graph for land suitability.

RESULTS AND DISCUSSIONS
The Study area is the capital region and one of the fast-developing townships in India. Raipur has witnessed a high growth rate in population, along with the rapid increase in infrastructure and residential colonies. At present the urban solid waste is being discarded at a site in a village called Sarona near to Kharun river which is a fifteenyear-old dump yard. The site is almost filled with solid waste and it may not be able to accommodate any further. Similarly, due to increase population, urbanization, and industrialization the quantum of Municipal Solid Waste generated increased many folds and unmanaged municipal solid waste disposal particularly has lead to serious socio-environmental problems. This Study signifies an important step in addressing a critical gap in the detection of landfill sites and to augment cost-effectiveness and efficiency of waste management efforts. Due to their ability to deal with large volumes of spatial information from various resources geospatial technology is ideal for site selection studies  (Poorna and G, 2016). In this Study, ancillary data from various parameters were obtained and after a descriptive analysis, surveyed studies are categorized based on the six criteria in a GIS environment. Then, we used MCDA to determine the relative importance of criteria to each other and WLC method to evaluate the land suitability. All digital maps of the Study area including topographical maps were registered to UTM coordinate system, zone 44N, WGS84 datum. GIS environment is able to perform suitability analysis using Multi-Criteria Decision Analysis (MCDA) and computed six (6) positive landfill site windows for overlay analysis (Karthiheyan and Yeshodha, 2016).

DRAINAGE AND SURFACE WATER SOURCE
The distance from surface water source and drainage is important criteria for selecting a suitable landfill site, because drainage has infiltration capacity. During the monsoon time water drip over drainage and contaminate the potable source of water. Solid waste disposal sites must not be located near to surface water (streams, rivers, lakes, and pond). The NGT directives stated that a 100 m buffer zone should be maintained around significant water bodies. Most of the surface water in the study area is in the form of streams and tank that occurred during heavy rains in monsoon season. Thus, a score value of 2 was given to a distance of ≤200 m, while a score value of 8 was given to distances of >600 m. A weighting value of 0.2 was given to this factor, because of its influence on the environment. Estimation of drainage distance from the stream is illustrated in Table 2 where 4 classes have been classified on the basis of relative distance from the surface water source (Poorna and G, 2016), 21.48% and 16.37% part of the Study area is highly suitable and moderately suitable respectively, whereas, 26.28% and 35.87% of the area are least suitable and not suitable respectively for landfill site.

TRANSPORT NETWORK
There is no specific rule of what should be the best distance to place the landfill site. Most studies suggested that the landfill site should be located within a 1 km buffer from the roads (Al-Hanbali et al., 2011; Chang et al., 2008;Delgado et al., 2008). The landfill sites should not be placed too far from the roads to decrease the cost of transportations. The road network in the study area was delineated from CartoSAT -1 Satellite Data and Survey of India Toposheet in GIS vector format. Using GIS spatial analysis, a buffer was created around road network at distances mentioned in Table 2. Considering the huge cost of transportation, it was decided to give a score of 4 to the a distance ranges from > 500 m, while distances of less than 500 m and more than 350 m were given a score of 8, as shown in Table 2. A weighting value of 0.2 was assigned to this factor, since this factor can be adjusted by planners and engineers based on the project conditions. According to the transportation network map for landfill sites shows in Figure 5, maximum area (45.41%) of the Study is not suitable and 27.2% of the Study area is least suitable, whereas, 18.91% and 8.48% of the area are moderately suitable and highly suitable, respectively for landfill site.

LITHOLOGY AND STRUCTURE
Lithology and structure of potential site turns out to be exceptionally remarkable part in decrease of the spread of contaminants (Şener et al., 2011) Lithology and structure shows that out of total Study area 72.92% is highly suitable and 18.43% is moderately suitable for landfill site, whereas, 7.13% and 1.52% of the Study area are least suitable and not suitable respectively and shown in Figure 6.

SOIL
Soil should be of sufficiently low permeability to significantly slow the passage of leached from the site (Fides K. Kirimi, 2014). Soil characteristics such as texture and depth shows that out of total Study area, 63.18% is highly suitable and 18.63% is moderately suitable for landfill sites, whereas, 7.17% and 11.02% of the area are and not suitable respectively and shown in Figure 7.

LAND-USE / LAND-COVER
The land-use / land-cover (LULC) map displays the land utilized by human and natural cover in the Raipur Urban Region including New Raipur area. The majority of the Study area is occupied by agriculture activity. Based on LULC suitability, out of total Study area14.26% is highly suitable and 64.07% moderately suitable for landfill sites, whereas, 0.88% of the area is least suitable. The remaining 20.80% of the Study area are not suitable for landfill sites and illustrate in Figure 8.

SLOPE
As per the new rules, construction of landfills on hills shall be avoided. However, transfer stations and processing facilities shall be operational in the hilly areas (Ministry of Environment and Forests Notification New Delhi, the 25th September, 2000). Slope map shows Study area dominated by slope of (0-2 degree) which is highly suitable region, subsequently, moderate sloping area (2-4 degree), least suitable area ( 4-10 degree), not suitable areas (>10 degree) and shown in Figure 9.

SUITABILITY ASSESSMENT
In this study, an arid area (Raipur Urban area as a case study) was selected. Presently, the landfills do not satisfy the required environmental criteria. Various criteria used in landfill site suitability analysis partially evolved and the relative importance of each parameter were determined. It is observed that the parameter used in landfill site selection have a different degree of influence. Seven of the most significant criteria were selected for this purpose. For suitable weight for each criterion, the multi-criteria decision-analysis (MCDA) methods were applied in the GIS environment. GIS-based study of spatial data has been a new specialized process, competent of analyzing complex problem of evaluating different geospatial features for targeting potential areas for siting landfills. Geospatial technique offers unique capacities for automating geospatial analysis for screening all possible sites. The suitable sites selection can be narrowed down using a prescribed MCDA process. This procedure will allow the planners and decision-makers to apply it in other areas in Chhattisgarh that have similar conditions when selecting a new landfill site.   To define the rank projection and topology creation of drainage, transport network, lithology, structure, soil, LULC, and slope were converted to separate raster files using weightage and score. For the site suitability analysis, all the raster datasets of each layer having different scores were overlaid and the scores of the individual layer were added using the raster calculator tool in GIS. The final scores were reclassified in four classes to generate a suitable map for landfill site which is illustrated in Figure 12. Finally, landfill sites were obtained for landfill in Raipur Urban Region including New Raipur area; the most potential sites are shown in Figure 13. The final results showed that there are more locations for landfills for old and new Raipur urban area. In the present Study there are sporadic areas identified as suitable sites for landfill location. In the site suitability analysis 25% area found not suitable for landfill siting, 51% least suitable and 22% moderate suitable. Out of the remaining area, 2% area is found most suitable (Table 3).
Based on the land suitability map, the existing solid waste disposal site, as illustrated in Figure 13, is located within "Least suitable" class. This gives an indication that the location of the existing disposal site is in critical situation. The presence of the existing disposal site very close to the river is not recommended, since it can increase contamination in the river water, there is the chances of the health risks to the people who are living near to the river. The areas of the selected sites were adequate to unload the cumulative quantity of solid waste for future solid waste dumping. The present waste disposal sites in Raipur Urban Region including New Raipur area do not conform to the environmental and scientific criteria, and it influences human health. In a landfill selection procedure, it becomes essential to review the reliability of the method involved in identification of the best candidate site. The study methodology was based on the experts opinion and previous studies in this field by giving proportion values for each assessment criteria according to its importance among other criteria Site selection for landfill corresponds to a complex process due to the implementation of different environmental criteria. Geospatial techniques provides statistical presumption facility in spatial environment which minimize the chances of error in work execution and corroborate that the geospatial techniques are preferable for landfill site selection which enables the identification of areas suitable to host a MSW because of their minimal effect on the environment, protect the human health and, on the other hand, respect the constraints and restrictions imposed by environmental law for landfill siting in scientific manner.
A field survey was conducted to check the conditions of the suggested alternative sites. It was found that most of the suggested sites, from environmental point of view, can be suitable for a new landfill site. But, in terms of planning and public opinion there might have different views, which might need further investigations, taking into consideration more detailed engineering, geotechnical, and hydrogeological studies.

CONCLUSIONS AND RECOMMENDATIONS
Raipur Urban Region including New Raipur area is unplanned and the city has a population density of about 6463/ km2 and generates about 600 tons of waste per day. Solid waste management and disposal in Municipal Corporation at its present status does not fulfill the required conditions (Jharia, 2014). The increasing generation of MSW in the urban area is one of the greatest challenges faced by governmental authorities. In order to mitigate the impacts on the environment and public health, a claim, which necessitates a fast decision making process for final disposal of the MSW, motivates this study. The present Study addresses landfill site management and disposal of Raipur Municipal Corporation to enhance the efficacy of landfill site management efforts. Urban wastes of the Study area consist of a highly assorted mass of pollutant from residential, commercial, and industrial activities to create an environmental problem. An assortment of disposal sites for solid wastes generated in the urban area has always been a challenging task and site selection is the complex process that should have a minimum environmental impact. Research findings show that a combination of MCDA with geospatial technique, featuring a well-structured architecture and the computational power, improves the application potential in urban and regional planning, and gives necessary support to the decision-maker in the appraisal of the waste management difficulty so that a higher level of understanding can be reached in regard to environmental decisions. It has been established beyond every reasonable doubt that geospatial technology is a very important tool for determining the most appropriate locations for setting disposal and it also helps to decide travel routes for waste transportation and disposal.
This present Study acquired data from various sources and integrated into a GIS environment to categorize suitable land for a proper selection process and suggest suitable landfill sites. The integration of GIS and multicriteria decision-making technique establish an environment for transportation and corroborating geospatial data for concern stakeholders. The Study suggests that many areas located in Raipur Urban Region including New Raipur area Urban Region can be alternate to present landfill sites might be suitable from the environment and economic point of view and it minimizes the environmental risk and human health. The present Study is useful for planner and researcher to serve as a guide for further planning, management and development of smart city waste disposals.

SOURCES OF FUNDING
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

CONFLICT OF INTEREST
The author have declared that no competing interests exist.

ACKNOWLEDGMENT
The Study is a part of experience in various project work carried out by the first author (Amit Prakash Multaniya) at Chhattisgarh Space Application Centre, CG Council of Science and Technology (CCoST), Govt. of Chhattisgarh. The authors are thankful to Mr. Mudit Kumar Singh, Director General, CCoST for encouraging and providing support to carry out this Study. Authors would also like to thank the staff of CGSAC group who was involved in this Study for their time and guidance.