multi criteria decision making based on dematel and anp techniques to select the optimum location for cemeteries, isfahan city, iran

introduction one of the major tasks of urban and regional planners is allocation of land to various urban utilizations according to the role and function of the city, urban economy, and also cross-effect of the land-uses with each other. this is the quantitative aspect of the subject, but what is more important is the qualitative aspect which means appropriate distribution and deployment of land-uses or applications on a physical level (optimal location of land-use). a planning in this way by appropriate land-uses help citizens enjoy the services and facilities offered in different parts of the city. this competent planning requires no additional commuting and will reduce environmental pollution, help to create safe urban space and acceptable environment, and provides peaceful, convenient living. cemeteries are the places where are considered as the essential services in urban areas. unfortunately, it is predicted that fullness and replenishment of cemeteries will leads to urban crisis in the next decade and finding other places for cemeteries will be unavoidable. necessity of having the second or third cemetery in urban areas is not only because of their replenishment or fullness but also it is due to their distance from the cities. this can be problematic for the citizens and make difficulties for the citizens to visit the graves. it seems that the idea of cemeteries development in different directions of the cities would makes the access to them easier for the citizens. nevertheless, urban planners still do not pay attention to establishment of new cemeteries in the cities according to the facts. due to the importance finding a suitable place for construction of cemetery in one hand and the complexity of the problem because of different effective factors on the other hand, selection of a suitable environment to model and solve the problem is very important to find the solution. according to studies and surveys conducted in geographical information system (gis) it was found that this system has excellent features and capabilities in collection, storage, retrieval, detection, integration, analysis, modeling, and displaying of geographic data. having these functionalities, gis can be used in site selection of urban centers such as cemeteries by involvement of qualitative and quantitative variables. moreover, gis can also be used as a strong decision support system in urban planning and management. therefore, to model and solve the optimization problem of finding a suitable place for a cemetery, the techniques in the mcdm is utilized in gis environment. materials in this study, environmental, social, and economic standards have been considered for finding a suitable place for constructing a new cemetery. effective criteria in locating the cemetery were identified using expert opinions and resources. included criteria are distance from city, distance from river, access to main road, slope, geology, soil, and land-use. after the criteria were identified, due to the lack of sufficient information about the amount of effectiveness and interaction of the factors with each other it was tried to make a weighting of the factors based on their relationships. distance from city: there are different reasons that the cemetery should be located away from the urban main structure. from the jurisprudential view, the maximum distance of cemetery from the city shall be such that not to break the prayer and revocation of fasting. on the other hand, given that the muslims are going to pilgrimage of the graves periodically (roughly every week), thus distance of cemetery should not be such that the citizens have access difficulties. it should not also cause transmission in many types of contaminations. however, for the favour of urbanism principles, distance between cemetery and the city is necessary, otherwise several problems such as the following will occurs: transmission of different types of pollutions including air pollutions due to burning of the dead costumes, interactions resulting from decomposition of corpses, contamination caused by burial in soil, noise pollution induced mourning and wailing voices of the survivors. psychological effects and depression of people, particularly for children who living around the cemetery, they are facing harrowing scenes of wailing every day. traffic due to mass movement of the participants in funeral ceremony. road access criteria: due to funeral ceremony and the events afterwards, commuting to the cemetery takes place in collective and group form. at specific days such as friday nights and some national religious occasions many people turn to the cemeteries. therefore, proper and safe access to these palces are very significant. it is to mention that sometimes funeral participants do not act rationally due to mental disorders. hence, if access way to cemetery is out of the town and if it consists of many intersections it may have safety issues. soil: in chemical interactions on corpse the soil type and material is highly effective. compounds that are high absorbent of water and or their absorption are very low, cause that the corpse remains in the soil for a long time. therefore, the soil material and its compounds should be such that not cause disorder in corpse decomposition. geology: in terms of permeability, the bedrock could be considered as primary necessities in selection of cemetery location. because very high permeability leads to groundwater pollution and in contrast low permeability leads to contamination of surface water. surface waters: cemetery should not be adjacent to river, fountain, and subterranean, because cemetery sewage and specially mortuary wastewater is highly contaminated and by no means should not contact the water for human, livestock, and farming consumption. land’s slope: topography of cemetery location should have suitable slope to rapid depletion of flowing surface waters, so that the water from rain and snow should not remain on the cemetery surface. the topography of the burial place should also be considered to determine the extent of required excavations and embankments for land leveling methods since finding a place for new cemetery requires criteria identification and weighting them as well, spatial multi-criteria decision making techniques in combination with gis capabilities in resolving such problems can play a key role in achieving the goal. in multi-criteria decision making there are several techniques in regards to site selection. in the current study and in order to select suitable location, anp, dematel, were used along with gis. in order to execute the site selection, fuzzy membership values determined for each phase and their corresponding fuzzy maps are prepared in arcgis software environment. in addition, for geological and soil criteria based on their types, discrete fuzzy values were devoted. in the final step, the obtained weights in network analysis process for each criterion were multiplied by the obtained fuzzy map for that criterion. results and discussion to determine an optimal location for construction of a new cemetery, after generation of the weighted fuzzy maps in arcgis environment, all proportional maps were combined in arcgis using gamma operator with the value of 0.7. the difference between suitable and unsuitable location are discerned in the operators. gamma value of 0.9 allocates greater areas to suitable location, and gamma 0.8 is also high percentage of suitable location. the results obtained from gamma value of 0.7 indicate that the area of unsuitable location is high and area of suitable location is low. as a result, the operator will assist us to determine the most suitable location. gamma operator has adjusted very high sensitivity of multiplication in fuzzy operator of fuzzy sum. the results obtained from this operator were used to execute the model for constructing cemetery. the selected locations from combination of all the effective factors give us a suitable location qualified all the hygiene and environment principles for places of the cemeteries. conclusions based on previous researches and the results of the current study, it can be argued that using spatial decision support system through dematel and anp techniques in gis environment by gamma fuzzy operators helps to execute an appropriate evaluation and the results close to the real world. dematel technique, by enjoyment of graph theory principles, can be applied to extract the relationships of cross-effectiveness and influence of the elements in the graph of the present study. thus, it can determine intense effects of the cited relations in the form of numerical scores. one of the advantages of this method compared with other decision making methods is use of feedback relationship. this means that in the structure of this technique each element can affect the same level of elements, upper and lower level elements as well, and in contrast takes effects from each of them. utilization of dematel for anp method is effective not only for calculation of influence level between different groups of factors but for matrix normalization. construction of cemetery in these places can avoid pollution emission in the city. the research suggests also the places for cemeteries in order to avoid traffic in the city.