چکیده:
افزایش سرعت شهرنشینی و همچنین مهاجرت به شهرها در چند دهه اخیر، الگوی توسعه فیزیکی شهرها را دچار تغییرات گستردهای کرده است. به منظور کاهش و کنترل اثرات نامطلوب توسعه کالبدی شهرها بر محیط زیست لازم است تا با برنامه ریزی دقیق، عرصههای مناسب توسعه شهری با توجه به توان اکولوژیکی سرزمین تعیین گردد. پژوهش حاضر با هدف ارزیابی توان اکولوژیکی شهرستان بم به منظور تعیین عرصههای مناسب جهت استقرار کاربری توسعه شهری با رویکرد استفاده از روشهای تصمیمگیری چند معیاره، سامانه اطلاعات جغرافیایی و منطق فازی به انجام رسیده است. با مرور پژوهشهای پیشین و استفاده از نظر نخبگان، 9 معیار و 13 زیرمعیار جهت انجام پژوهش تعیین گردید. تمامی معیارها و زیرمعیارها پس از وزندهی، با استفاده از روشهای تصمیمگیری چند معیاره و نرم افزار Expert Choice مقایسه شدند. از نرم افزار Arc GIS 10. 3 به منظور استاندارد سازی نقشهها و از روش ترکیب خطی وزندار جهت روی همگذاری لایههای اطلاعاتی استفاده شده است. نتایج نشان داد، بیشترین ارزش پیکسلی مناطق برابر با 481/0 و کمترین ارزش نیز برابر با 07/0 است. با طبقهبندی نقشه نهایی در چهار طبقه، مشخص 24% از مساحت منطقه معادل 2/189965 هکتار دارای توان متوسط، 34% معادل 3/268854 هکتار ضعیف، 22% معادل 7/178695 هکتار بسیار ضعیف و 20% معادل 3/160762 هکتار غیرقابل توسعه است. پراکنش مناطق با توان اکولوژیکی متوسط عمدتا در قسمتهای شرق، شمالغرب و به میزان کمتر در مرکز منطقه و پراکنش مناطق با توان بسیار ضعیف و غیرقابل توسعه در محدوده غرب و جنوب منطقه قرار دارند. با توجه به نتایج بدست آمده میتوان بیان کرد به دلیل شرایط خاص منطقه و پتانسیل لرزه خیزی بالا ناشی از وجود شبکه گسلی و عوامل زمین ساخت، منطقه مطالعاتی از پتانسیل متوسطی جهت استقرار کاربری توسعه برخوردار است.
Background and Objective In recent decades, with the acceleration of urbanization and the growth of migration to cities, the physical structure of cities has undergone extensive changes. To implement these changes, regardless of the ecological capacities and requirements of sustainable urban development, cities are facing many challenges. One of these challenges is determining the appropriate areas for the physical expansion of the city for the establishment of urban development. One of the most reliable methods to determine the appropriate directions and areas for urban development by considering environmental conditions and characteristics is the land suitability assessment. Such an assessment greatly contributes to sustainable land use and solving environmental problems caused by rapid urban development. Land suitability assessment aims to identify the most appropriate spatial pattern for future land uses considering the ecological potential of the area. Since many criteria need to be considered and analyzed in the selection of appropriate lands for urban development, it is necessary to use the most effective techniques to identify the best locations for future urban expansion. The Geographic Information System is such a technique, having its most useful application in the land suitability assessment method. In setting the importance of the criteria used and computing the weights of factors, GIS tools must be integrated with other methods to improve the results. Given that, the present study attempted to evaluate the land suitability to determine suitable areas for the establishment of urban development of Bam city through the integration of the Multi-Criteria Decision-Making approach, Fuzzy Logic, and Geographic Information System.Materials and Methods To achieve the objectives of this study, with the help of a group of experts, and an extensive review of the related literature, all the criteria and sub-criteria essential to the establishment of urban development were identified as the first step. To this end, a questionnaire was designed and distributed among the group of experts and they were asked to express their opinions on the identified criteria and sub-criteria. To determine the required sample size and population, Morgan’s sampling table was employed. Consequently, 9 criteria and 13 sub-criteria were selected for the land suitability assessment in this study. Multi-Criteria Decision-Making method and Expert-Choice software were used to compare and weigh the previously determined criteria and sub-criteria. As the next step, all the data layers were standardized by the fuzzy logic method using ArcGIS software. The scale of the maps used in this research is 1:100000 and the resolution of digital layers is 90×90 meters. After assigning calculated weights to each data layer, they were overlaid using the Weighted Linear Combination method and fuzzy sum technique.Results and Discussion The results from MCDM analysis revealed that three sub-criteria namely distance from major faults, distance from drinking water wells, and soil texture had the highest weights among other factors at 0.235, 0.117, and 0.114, respectively. The inconsistency calculated for the pairwise comparison in this study was 0.07, which is below the 0.1 thresholds. Analysis of the final raster suitability map, resulting from overlaying data layers, showed that the highest and the lowest pixel values were 0.481 and 0.07, respectively. To perform a more accurate analysis, the final suitability map was classified into four suitability classes (medium, low, very low, and undevelopable) indicating that 24% of the studied area equivalent to 189965.2 hectares, categorized as having medium suitability, 34% low equivalent to 268854.3 hectares, 22% very low equivalent to 178695.7 hectares, and 20% undevelopable equivalent to 160762/3 hectares for the establishment of urban development. The medium suitable areas are mainly located in the east, northwest, and to a lesser extent in the center, mostly away from the major fault lines, while the areas of very low suitability and undevelopable are mainly located in the west and south of the area studied. Due to their proximity to protected areas, mountainous, fault lines, and hills, these areas do not demonstrate the appropriate suitability for the establishment of urban development.Conclusion This study was conducted to identify and determine suitable areas for the establishment of urban development in Bam city using a combination of the Multi-Criteria Decision-Making approach, Geographic Information System, and Fuzzy Logic technique. All the criteria and sub-criteria, used to conduct this study, have been determined using a questionnaire and considering the environmental conditions and socio-economic characteristics of the studied area. As a result, 9 criteria including water resources, climate, topography, geology, soil, areas under the Department of Environment Management, roads, population centers, and land use, and 13 sub-criteria including distance from surface and groundwater resources, climate, wind speed, slope, altitude, distance from the main faults, geology, soil texture, distance from protected areas, distance from roads, distance from built-up urban areas and land use were selected for this study. Expert Choice and ArcGIS software were employed for pairwise comparison and standardization and overlaying data layers. It was found that 24% of the studied area equivalent to 189965.2 hectares can be categorized as medium suitability for the establishment of urban development. Based on the final results, it is concluded that the integration of the Multi-Criteria Decision-Making approach, Fuzzy Logic, and Geographic Information System can provide sufficient tools to determine the areas suitable for urban development and present a detailed analysis of these areas according to the characteristics of the area for future planning.