New method for residential land suitability modeling using fuzzy IOWA group decision making method

Introduction During recent years، employing GIS and combine it with multi criteria decision making (MCDM) methods، have been extensively utilized to model land use suitability. However these models are mainly based on individual decision making approach and group based decision making methods have rarely been developed for land use suitability analysis. To model land use suitability، usually different factors such as climate، existing land cover/land use type، access to infrastructure such as road، gas and power، latitude، distance from earthquake hazard zones، access to water resources and etc should be considered. Due to the various stakeholders in this process، it is necessary to integrate the difference of opinions of different groups in the model. As a result، land use suitability analysis should be done based on group decision making approach involving various groups of experts. In this paper a group decision making model based on fuzzy-IOWA method is developed for residential land suitability analysis. This model is implemented in Kermanshah province. 2- Theoretical bases In this study، Fuzzy OWA and Induced OWA (IOWA) utilized in GIS environment to model land suitability in residential areas in Kermanshah province includes Kermanshah، Harsin، Kangavar، Sahneh and Songhor cities. Based on interview with four experts (an environmentalist، a civil engineer، an agronomist and an irrigationist) ten main criteria have been determined. Then، each expert determined the importance of each criterion individually. Next، factor maps related to each criterion were aggregated based on the preferences of each expert using of IOWA method. Some experts are optimistic and accept risk and others have opposite opinion. Fuzzy OWA method due to quantify linguistic variables allows to adopt different decision strategies of experts. As well as the IOWA make it possible to filter expert preferences that are incompatible with the opinion of the others. 3- Results and Conclusion Each criterion defines a factor map. Based on the expert’s preferences the weight of each factor map was calculated. Fig. 1 illustrates hierarchical structure of various criteria. Fig. 5 demonstrates the results of the model in the case study area. This figure presents the suitability maps related to the preferences of each expert as well as final suitability map resulted from the developed group decision making model. The figures show clearly the difference of opinions of experts. For example، Sahneh city is classified as high suitable in some individual maps but medium suitable in final group map. This city is in an earthquake zone with very high risk and has weak access to infrastructures، so considering this city as very high suitable is not reasonable. Using of the developed group based model، this city is classified as moderate as a result of assigning high weight to similar experts’opinions using of IOWA method. With review the final suitability map، can be observed that Bisetoon and Kermanshah are classified as high suitable، because of their good situation to access to roads، energy network and water resources، as well as placed far from the earthquake hazard zones. According to the results، in the case study area 59249، 358502، 439642، 175302 and 124902 hectares are defined as high suitable، suitable، moderate، pretty unsuitable and unsuitable، respectively.