تبيين ارتباط فرم‌‌شهري با تاب‌آوري در برابر سوانح در سطح محلات كلان‌شهر تهران

Analyzing Relationship between Urban Form and Disaster Resilience at Tehran Metropolis Neighborhoods

درك فرم‌شهري تاب‌آور بسيار مهم و ضروري است زيرا در فرايند برنامه‌ريزي شهري، مصرف منابع، پويايي و حتي حيات شهر پس از مواجهه با سانحه تحت تأثير تصميمات پيشين در زمينه ساختار كالبدي شهرها است. فرم‌شهري به‌عنوان ساختار شهر بر فروپاشي و يا پايايي سيستم شهري در برابر سوانح مي‌تواند تأثير بگذارد. ازسوي‌ديگر، فرم‌شهري به‌مثابه نمود فضايي و كالبدي فعاليت‌هاي انساني، بستر و زمينه‌اي براي ابعاد مختلف اجتماعي، اقتصادي، زيست‌محيطي تاب‌آوري است. با وجود تأثير فرم‌شهري بر تابآوري، فرم‌شهري تاب‌آور همچنان به‌عنوان يك موضوع اكتشاف‌نشده تاب‌آوري شهري است. در اين پژوهش با تكيه بر ويژگي‌هاي شهر تاب‌آور، ويژگي‌هاي فرم تاب‌آور همچون استحكام، تنوع، ارتباطي، كارآمدي، افزونگي و مدولاريتي معرفي‌ شده‌‌است. سپس با هدف شناسايي مؤلفه‌هاي فرم‌شهري كه ويژگي تاب‌آوري را دارند، ارتباط معني‌دار شاخص‌ها و مؤلفه‌هاي فرم‌شهري با تاب‌آوري و ابعاد آن تبيين شده‌است. براي اين كار، در اين پژوهش با انتخاب محلات كلان‌شهر تهران به‌عنوان محدوده موردمطالعه (368 محله)، پس از تعيين و سنجش ابعاد تاب‌آوري و مؤلفه‌هاي فرم‌شهري با استفاده از تحليل عاملي، از تحليل رگراسيوني جهت تبيين ارتباط ميان مؤلفه‌هاي فرم‌شهري و تاب‌آوري و ابعاد آن استفاده شده‌است. نتايج حاكي از آن است كه مؤلفه‌هاي مختلف فرم‌شهري بر عوامل مختلف تاب‌آوري تأثير متفاوت گذاشته و در برخي موارد، رفتار متضادي بر مؤلفه‌هاي تاب‌آوري داشته‌اند. در ميان ابعاد تاب‌آوري، تاب‌آوري جامعه‌اي هيچ تأثيري از مؤلفه‌هاي فرم‌شهري نمي‌گيرد. بيشترين ارتباط ميان مؤلفه متراكم بودن با تاب‌آوري زيرساختي مشاهده شده‌است. بعد اجتماعي و تاب‌آوري كل بيشترين ارتباط را با مؤلفه دسترسي به قطعات داشته‌اند. درمجموع ارتباط مستقيم مؤلفه‌هاي دسترسي به حمل‌ونقل عمومي و دسترسي به قطعات و ارتباط معكوس مؤلفه‌هاي دسترسي به مراكز تجاري و ميزان فضاي باز و سبز با تاب‌آوري و ابعاد آن، نشان از تأثير مؤلفه‌هاي فرم‌شهري بر افزايش يا كاهش تاب‌آوري در برابر سوانح دارد.

While it has been only two decades since resilience as a concept entered the field of urban planning, there has been an increasing interests and a wide range of studies surrounding the issue in this short span of time. Considering this fact, surprisingly a few passionate endeavors have attempted to assess "urban resilient form" as the subject, while urban form as the structure of the city can directly influence its collapse or resistance in facing the disasters. In fact, variation in the form of a city can have a negative or positive influence on its resilience. Moreover, urban form as the spatial and physical embodiment of social and economic interactions of cities is the context of various social, economic, and environmental aspects of resilience. So it is a bit of a surprise that despite this undeniable influence of urban form on resilience, their relationship has not been thoroughly explored. Thus, by considering the features of resilient city this research has attempted to embark on redefining the urban structure from the resilient point of view and determined certain characteristics of 'urban resilient form' such as robustness, connectivity, redundancy, modularity, diversity and efficiency. Then, for obtaining the qualities of resilient urban form, it is tried to analyze a meaningful relationship between the indicators and factors of urban form and the extent of resilience, in order to specify urban resilient form together with the contributing factors affecting its resilience. Multi-dimensional urban form and resilience together with the impact of the scale on the components and parameters make it necessary to investigate the phenomenon and their relationship in a specific scale. This research takes neighborhoods’ scale to look at its case study, Tehran metropolitan area, in order to assess its resilience in the face of disasters, in addition to specify the modifier indicators of urban form in the neighborhoods of Tehran metropolitan city and examine the relationship between the components of the urban form and resilience. For achieving the aim of the study, initially the indicators and the scale of resilience in 368 neighborhoods have been evaluated to access the relation between the urban form and resilience scale. It benefits assessable indicators suggested by three resilience assessment approaches; CDRI, CRI, and BRIC, in the scale of neighborhood units. By taking the advantage of exploratory factors analysis, four domains of infrastructure, economic performance and community have been specified and then according the points which the factors obtained, the resilient degree of the neighborhoods were specified. Furthermore, the collection of six factors including denseness, green and vacant area accessibility, non-permeability, retail accessibility, components and transit accessibility along with 22 indicators are introduced as factors and indicators for urban form in the neighborhoods of Tehran metropolitan city. Finally, for obtaining the main goal of study which is illuminating the relation between urban form and resilience indicators in the neighborhoods of Tehran metropolitan city, linear regression analysis has been applied. The results of this analysis show that different urban form components have various and even contrasting influences on resilience. The strongest relationship can be found between infrastructure resilience and density, as the main component of urban form. The economic performance aspect is also, like infrastructure resilience feature, has been most positively influenced by density factor. Among all of urban form factors, accessibility to components has the most powerful bond with social aspect and the whole resilient composite index. Community resilience is not influenced by urban form components at all and there is no relationship between them whatsoever. There is a direct relationship between accessibility to public transportation and components availability with resilience. On the other hand, factors such as accessibility to business centers and the amount of open and green spaces have a reverse relationship with it. Overall, the influence of urban form components on increasing and decreasing the degree of resilience can clearly be demonstrated. However, the results of the effects of urban form components on resilience pose challenges for future studies. Economic performance dimension aside, these challenges include the negative impact of the density component on social resilience, the negative impact of the permeability component on infrastructure resilience and the negative impact of access to business centers on the dimensions of resilience.