تعیین مکانهای بهینۀ دفن نخاله‌های ساختمانی در شهرهای هموار و بیابانی با استفاه از سیستم اطلاعات مکانی و تکنیک شباهت به گزینۀ ایدئال (مورد مطالعه: شهر یزد)

نخاله‌های ساختمانی یا زباله‌های ساخت‌و‌ساز و تخریب به‌عنوان زباله‌های جامد تعریف می‌شود که بر اثر ساختمان‌سازی، بازسازی، تخریب ساختمان‌های مسکونی و غیرمسکونی و زیرساخت‌هایی از‌قبیل جاده‌ها، پل‌ها و غیره به وجود آمده و به‌عنوان یکی از موضوعات مهم و حیاتی در‌سطح جهانی شناخته شده است. این نخاله‌ها از وجوه مختلف اقتصادی، محیط زیستی و تکنولوژیکی نیازمند ملاحظات بیشتری است. هدف از پژوهش حاضر مکان‌یابی دفن ضایعات ساختمانی در شهر هموار و بیابانی یزد (شهری که با سرعت در‌حال توسعۀ کالبدی و بازسازی و نوسازی بافت‌های قدیمی آن است) با استفاده از سیستم اطلاعات مکانی و تکنیک شباهت به گزینۀ ایدئال است. به‌علاوه، وجود صنایع کاشی و سرامیک، کوره‌های آجرپزی و سفال‌سازی، معادن متعدّد شن و ماسه، سنگ‌های ساختمانی و موارد متعدّد دیگر سبب تولید حجم انبوهی از ضایعات ساختمانی شهری در سال‌های اخیر شده است که این ضایعات به شکل قانونی و غیرقانونی در مناطق پیرامونی شهر یزد تخلیه و رها شده و علاوه‌بر ایجاد مناظر بسیار زشت و ناپسند در حومۀ شهر آثار و پیامدهای زیست‌محیطی زیادی را بر‌جای گذاشته است. از‌جمله پیامد‌های زیست‌محیطی می‌توان به وارد‌شدن حجم زیادی از این رسوبات به معابر شهری پس از بارندگی‌های رگباری دو-سه سال اخیر و یا ایجاد گردو‌غبار و آلودگی هوا اشاره کرد. برای انجام‌دادن این پژوهش در ابتدا شاخص‌های بیست‌گانه‌ای بر‌پایۀ نظر‌های کارشناسان (ارتفاع، شیب، پوشش گیاهی، مرتع، منابع آب‌های سطحی، آب‌های زیرزمینی چشمه، چاه، قنات، خاک، مناطق شهری و روستایی، مراکز فرهنگی، فرودگاه، راه‌آهن، خطوط انتقال آب، گاز و برق، راه‌های ارتباطی و مناطق صنعتی و معادن) انتخاب و سپس این داده‌ها در سامانۀ اطلاعات جغرافیایی به شکل لایه‌های اطلاعاتی در‌آمد و در‌نهایت، هر‌یک از این شاخص‌ها بر‌پایۀ نظر متخصصان حریم و چارچوب لحاظ شد. در پایان، همۀ لایه‌ها روی‌هم‌گذاری شد تا نقشۀ مکان‌های بهینه برای دفن ضایعات ساختمانی مشخص شود. در‌ادامه، مناطق پیرامونی شهر یزد که شهرداری آنها را به‌عنوان مکان‌های مجاز دفن نخاله‌ها معین کرده بود، بر‌اساس تکنیک چند‌شاخصۀ تاپسیس ارزیابی و به‌دنبال آن مکان‌های بهینۀ دفن ضایعات ساختمانی اولویت‌بندی شد. بر‌اساس نتایج حاصل از روش شباهت به گزینۀ ایدئال چهار منطقۀ مجاز تعیین‌شدۀ شهرداری شامل شحنه، خلدبرین، گود محمودی و محدوده پارک کوهستان به‌ترتیب 0.402، 0.612، 0.403 و 0.443 امتیاز گرفتند. بدین ترتیب، بر‌مبنای همۀ شاخص‌های زیست‌محیطی، اقتصادی و زیبایی‌شناسی منظر مناطق شمال شرق شهر یزد برای دفن نخاله‌های ساختمانی شهری بر سایر گزینه‌ها ارجحیت دارد.

landfill site selection for construction and demolition waste in plain and desert cities using spatial information system and topsis (case study: yazd city)

abstractconstruction and demolition (c&d) waste is a significant urban solid waste issue arising from the construction, renovation, and demolition of buildings and infrastructure. this study focused on the optimal location for c&d waste disposal in yazd, a rapidly developing city facing challenges related to urban waste management. the flat desert landscape of the area had become a common site for both legal and illegal dumping, leading to unsightly scenes and environmental consequences, including the influx of fine-grained materials into the city from floods and winds.through a combination of library and field studies, we identified 20 critical criteria for locating c&d waste disposal sites, including distance from residential areas, water sources, land use, and soil conditions. these criteria were processed using geographic information systems (gis) to create layered information for analysis. the topsis multi-criteria decision-making technique was then applied to prioritize potential landfill sites.findings indicated that proximity to residential centers and water sources were crucial in the short term, while long-term considerations included the impact of wind and drainage patterns. the northeastern areas of yazd were identified as the most suitable places for c&d waste disposal, with 4 legal sites—shehneh, kholdebarin, gawd-e-mahmoudi, and kouhistan park area—scoring the highest based on the evaluation. the results underscored the need for effective waste management strategies to minimize environmental pollution and enhance urban aesthetics. future research could explore the application of this model in other regions facing similar challenges. keywords: siting, construction & demolition (c&d) wastes, landfill, yazd, environment.introductionconstruction and demolition (c&d) waste is classified as urban solid waste generated from the construction, renovation, and demolition of both residential and non-residential buildings, as well as infrastructure, such as roads and bridges. this issue is recognized as a significant global concern that requires careful consideration from economic, environmental, and technological perspectives. the purpose of this study was to identify optimal locations for c&d waste disposal in yazd, a rapidly developing city that was simultaneously undertaking the renovation of its older structures. the flat terrain surrounding yazd had made it a common site for landfilling urban solid waste, particularly c&d waste. the presence of local industries, including tile, ceramic, and brick manufacturing, along with numerous sand and stone quarries, had contributed to a significant increase in urban construction waste in recent years. unfortunately, this waste was often dumped both legally and illegally in the areas surrounding yazd, resulting in unsightly landscapes and various environmental repercussions. one notable consequence was the infiltration of fine-grained materials into the city due to floods and strong winds, which posed additional challenges for urban management and environmental sustainability. materials & methodsthis research involved a comprehensive approach that included both library and field studies, as well as direct observations of various construction waste landfill sites. in the initial phase, we identified key criteria for locating urban solid waste, specifically focusing on plain and desert cities, drawing on the insights of experts and existing research. we established 20 critical indicators, which included elevation, slope, vegetation, pasture, surface water sources, underground water sources (such as springs, wells, and qanats), soil type, urban and rural land use, cultural centers, airports, railways, and the locations of water, gas, and electricity transmission lines, as well as communication roads, industrial areas, and mines. these data were then transformed into informational layers using geographic information systems (gis) for processing. each indicator was analyzed and standardized based on expert opinions. the layers were subsequently overlaid to create a map indicating optimal locations for the landfill of construction and demolition waste. to combine the maps, we assigned weights to each layer, determined their boundaries in the gis, and then overlaid the boundary layers. following this, we evaluated the areas surrounding yazd that had been designated by the municipality as legal disposal sites for construction waste using the topsis multi-criteria decision-making technique. this process allowed us to prioritize the most suitable locations for waste disposal. research findingsthe findings indicated that all 20 parameters evaluated in this study played a crucial role in determining the optimal locations for urban c&d waste disposal. however, some parameters were particularly significant and warranted greater attention. for instance, the distance to residential centers—both urban and rural—as well as the proximity to surface and underground water sources, land use, geology, soil type, and suburban communication roads were more favorable in the short term. in contrast, factors, such as the direction of the dry river network and the orientation of both primary and secondary winds were more critical for long-term site selection. c&d waste could weather relatively quickly and was susceptible to wind and heavy rainfall, especially during monsoon seasons, leading to flooding in dry riverbeds. as a result, substantial amounts of this material could be transported back into the city. based on the analysis of various human and natural factors influencing the siting of c&d waste disposal and the results obtained using the topsis method, 4 legally designated areas identified by the municipality—shehneh, kholdebarin, gawd-e-mahmoudi, and kouhistan park—were evaluated, yielding scores of 0.402, 0.612, 0.403, and 0.443, respectively. consequently, the northeastern areas of yazd city emerged as the most suitable locations for the disposal of urban construction waste, considering the environmental, economic, and aesthetic indicators. discussion of results & conclusionthe significant production of construction and demolition (c&d) waste in yazd city could be attributed to rapid urban development, extensive reconstruction and renovation of old buildings and infrastructure, and the presence of nearby tile, ceramic, and brick factories. additionally, most of the surrounding land was flat and desert-like, encouraging residents and factory owners to dispose their construction waste in the nearest available locations. this tendency was further exacerbated by the desire to reduce transportation costs. consequently, both legal and illegal dumping of construction waste had marred the aesthetics of the city’s surroundings, particularly along the main access roads.dumping c&d waste in natural environments leads to significant alterations in the landscape and geomorphological features. these changes disrupt natural processes, including drainage systems, soil permeability, and vegetation levels, while also increasing erosion rates and affecting wind patterns and land subsidence. such alterations pose risks to environmental stability, including changes to ecosystems, increased vulnerability of aquifers, heightened flood risks, and exacerbated dust production. therefore, selecting suitable locations for landfill sites is crucial to mitigate environmental degradation and pollution (paz et al., 2020). failure to address the environmental impacts of construction waste can lead to severe air, water, and land pollution (chen et al., 2018; moustakas et al., 2023).to identify optimal locations for burying c&d waste, all areas surrounding yazd city were evaluated, including those legally designated by the municipality for waste disposal, as well as those used illegally by residents. while the land around yazd was predominantly desert and deemed unsuitable for many uses, numerous areas were found to be unfavorable for landfilling c&d waste. according to the results obtained through the topsis technique, which guided the creation of a final location map, the central urban areas were unsuitable for waste disposal due to the presence of residential buildings, surface and underground water sources, and power transmission lines. greater emphasis was placed on factors, such as proximity to urban and rural areas, water resources, and power transmission lines when determining suitable sites for c&d waste. additionally, other influencing factors, including the presence of mines, industrial sites, roads, topography, vegetation, rural settlements, soil type, and sediment characteristics, ruled out the western, eastern, and southern regions of yazd as viable landfill sites. for instance, the west and southwest areas were characterized by numerous suburban roads, an airport, and both urban and rural residential zones, alongside mining and industrial facilities. these regions were also subject to prevailing winds from the west and northwest, as well as the drainage patterns of several dry rivers oriented south-north and southeast-northwest. consequently, the northeastern parts of yazd emerged as the preferred locations for c&d waste landfilling. the findings of this research highlight the effectiveness of multi-indicator evaluation techniques in identifying suitable sites for urban solid waste disposal, a strategy supported by similar studies conducted in various regions worldwide (banias et al., 2010; aragones et al., 2010; araiza et al., 2019; yuan et al., 2022).