تبیین چگونگى تاثیر فرم شهرى بر تاب آورى در برابر سوانح در سطح محلات کلان شهر تهران

فرم شهری به عنوان الگوی توزیع فضایی فعّالیّت های انسان می‌تواند نقش مهمی در ارتقا و یا کاهش تاب‌آوری شهری در برابر سوانح ایفا کند. یکی از سوالاتی که در مورد نحوه ارتباط این دو موضوع مطرح می شود این است که آیا فرم شهری در یک مقیاس خاص که متشکل از مولفه‌ها و شاخص‌های مختلف است، می تواند به عنوان یک بعد از تاب‌آوری در کنار دیگر ابعاد آن از قبیل بعد اجتماعی، اقتصادی، زیست‌محیطی، زیرساختی، جامعه‌ای و نهادی در نظر گرفته‌شود و یا فقط برخی از مولفه‌های فرم شهری بر ابعاد تاب‌آوری تاثیر دارند. ازآنجایی که مدل‌سازی این امکان را فراهم می کند که متغیرها از چه مسیرهایی بر یکدیگر اثر می گذارند و اینکه اثرگذاری با چه شدت و جهتی است، در این پژوهش کلانشهر تهران و 368 محله آن به عنوان محدوده مطالعاتی انتخاب شد. پس از تبیین مولفه‌‌ها و ابعاد فرم شهری و تاب‌آوری با استفاده از تحلیل عاملی اکتشافی در سطح محلات،  با تدوین دو مدل معادلات ساختاری، ارتباطات میان فرم شهری و تاب‌آوری و مولفه‌های آنها تبیین شد. نتایج حاکی از آن است که با وجود اینکه شاخص ترکیبی فرم شهری ارتباط معنی داری با تاب‌آوری ندارد، مولفه‌های فرم شهری در سطح محلات بر ابعاد تاب‌آوری تاثیرات متفاوتی می‌گذارند.

assessing how urban form effects on disaster city resilience: at tehran metropolis neighborhoods

urban form as the physical structure of the city, directly affects its ability in confronting natural disasters. besides, as the spatial and physical presentation of human activities is the main context for various social, economic, and environmental aspects of urban resilience. nevertheless, resilient urban form is still unknown in city resilient literature and despite the abundance of studies on urban resilience, research on the link between this quality and urban form is limited and fragmented. resilience literature has defined resilient city charactresics and has set social, economic, infrastructural, institutional, environmental and community domains to achieve disaster resilient city. in order to understand how urban form can affect city resilience, this research based on resilient city characteristics, redefines urban form qualities such as robustness, redundancy, modularity, diversity, and efficiency as resilient urban form qualities. thus, this study sheds more light on the relationship between urban form and resilience by assessing the relationship between these two phenomena to find out whether urban form can be one of resilience domains or only resilience domains can be affected by urban form’s components, based on explanatory, experimental and exploratory methodologies. the study area is tehran metropolis and explicitly focuses on its 368 neighborhoods. for this purpose, first, community disaster resilience in tehran metropolis is assessed. in this regard, a set of resilient indicators extracted from three evaluation models (bric، cri و cdri) were used to evaluate and construct a resilient composite index for tehran metropolis. by using exploratory factor analysis, the resilience dimensions are shown in four social, infrastructure, economic performance, and community domains. second, urban form components are evaluated in the scale of a neighborhood, explaining six factors of denseness, green and vacant area accessibility, non-permeability, retail accessibility, plot accessibility and transit accessibility. then, to achieve the main objective of this research, evaluation of the relationship between urban form and resilience, structural equation modeling (sem) are applied. therefore, in the present study, to find the relationship between resilience and urban form, two structural equation models are designed in amos software and analyzed by path analysis method. in the first model, urban form and resilience were considered as hidden variables, each of which was introduced based on its respective components and dimensions. as this relationship wasnot significant, the urban form cannot be considered as one of the dimensions of resilience. then, the relationship between the components of the urban form and the resilience dimensions in the second model was analyzed to obtain the relationships between them. the results show that (1) none of the urban form components has significant effect on community resilience, (2) urban form components play different roles on various domains of urban resilience, in which denseness component as a major component of urban form has positive impact on infrastructure resilience but access to plot has significant impact on social resilience as a main domain of resilience. the other two urban form components such as transit and retail accessibility have positive impact on three social, infrastructure and economic performance. in sum, however urban form cannot be defined as an individual domain of urban disaster resilience, its elements and components have a significant impact on different aspects of resilience and resilient policies.