تحليل شاخص‌هاي آسيب‌پذيري مساكن شهري در برابر خطر بلاياي طبيعي (مطالعه موردي: مساكن شهر اصفهان)

Analyzing the Vulnerability Indices of Urban Dwellings to the Natural Disasters Danger (Case Study: Isfahan’s Dwelling)

امروزه در كشور ما شهرنشيني رشد فزاينده‌اي يافته و هر ساله در كشور شاهد پيدايش شهرهاي جديدي هستيم. نظر به اين كه ايران به دليل شرايط خاص طبيعي و جغرافيايي خود، همواره در معرض خطر بلاياي طبيعي بوده و حوادث ناگواري را تجربه كرده است، به نظر مي‌رسد كه برنامه‌ريزي جهت مصون‌سازي هرچه بيشتر مساكن شهري ضرورت دارد. هدف پژوهش حاضر شناسايي وضعيت آسيب‌پذيري مساكن شهر اصفهان در برابر خطر بلاياي طبيعي و اولويت‌بندي شاخص‌هاي مورد بررسي بوده است. نوع تحقيق به صورت پيمايشي، تحليلي و مبتني بر مشخصات كمّي و كيفي مساكن شهر اصفهان است و جامعه آماري را مساكن شهر اصفهان تشكيل داده و روش و طرح نمونه‌برداري به صورت نمونه‌برداري احتمالي بوده است. در اين راستا مساكن مناطق 14گانه شهر اصفهان به عنوان حوزه آماري انتخاب گرديد و داده‌ها‌ي مورد نياز جهت مطالعه شامل داده‌هاي فضايي (شبكه معابر محدوده به تفكيك عرض، واحدهاي تفكيكي در مقياس قطعات ملكي، انواع كاربري‌ها شامل اطلاعات لازم از جمله مساحت قطعات، نوع كاربري و...) و داده‌هاي آماري و توصيفي (نوع كاربري، تعداد طبقات، نوع سازه، تراكم ساختماني، تراكم جمعيّتي تعداد خانوار در واحد مسكوني، تعداد جمعيّت هر واحد مسكوني، كاربري‌هاي خطرناك، عمر سازه‌ها، سال تاسيس بنا و...) بود. پس از جمع‌آوري داده‌هاي مورد نياز، پايگاه اطلاعاتي لازم در محيط نرم‌افزاري SPSS تشكيل شد. حجم نمونه به صورت نمونه‌گيري احتمالي با استفاده از فرمول كوكران با سطح اطمينان 5/95، تعداد 340 نمونه محاسبه شد و در نهايت با مقايسه آسيب‌پذيري وضع موجود در مناطق 14گانه شهر، شاخص‌هاي آسيب‌پذيري مسكن اولويت‌بندي گرديد. نتايج پژوهش نشان داد كه ميزان آسيب‌پذيري مساكن شهر در برابر خطر بلاياي طبيعي زياد است و مشخص شد كه متغيرهاي «دسترسي به ساختمان»، «دسترسي به طبقات ساختمان» و «قدمت بنا» بيشترين تاثير را در آسيب‌پذيري مساكن شهر دارند.

Introduction Nowadays, the vulnerability of human’s dwellings to the natural disasters has been steadily increasing as the results of the population centralisation. Economic activities in vast and dense regions and disorganised and irregular conditions of dwellings in which the low-income dwellers of urban and rural areas live. The scale of damage caused by a crisis is not only related to its destructiveness power but largely to the quality of infrastructural structures exposed to the incident. With respect to the size, population and economic, political and social importance of Isfahan and potential and actual threats, the vulnerability of the city dwellings to the natural disasters crisis is completely tangible and evidence when compared with equipment and facilities corresponding the world standards, population threshold features and the range of various dangers. The aim of this article is to identify and prioritize the dwellings vulnerability indices in Isfahan’s 14-fold zones. The spatial domain of this survey is the 14-fold zones of Isfahan based on the following hypothesis: Dose the structural architecture of Isfahan dwellings have a suitable performance against the natural disasters crisis? What are the initial zones and indices need to be considered? Study Area The study covers Esfahans Fourteen zones. Esfahan, in the center of Esfahan Province, has been located on one of the central thoroughfare of the country. This city is filled with a set of valuable historic monuments which distinguish it from other cities; Therefore, it necessitates more attention to it from a geologically. Esfahan plain has been situated in the Sanandaj _ Sirjan zone. Material and Methods The studying variables are quantitative and qualitative characteristics of Isfahan dwellings and the measurement of their vulnerability rate. Sample size has been accounted for 340 samples as probability sampling using Cochran formula with a confidence level of 95.5. In addition to the available statistics about the qualitative and quantitative characteristics of dwellings and vulnerability conditions of Isfahan, data collecting tools as well as other tools such as observation, questionnaire, map, field work, Internet resources and library resources have been utilised. To determine the reliability of the data collecting tools, the superficial reliability technique has been applied. To study the group vulnerability, “dwellings qualitative and quantitative indices” have been analysed using statistical models and methods. Results and Discussion Initially, the proportion and the rank of each different variable on vulnerability rate of the city dwellings have been analysed. To do this work, regarding the score of responders to each class of variables and then summing the resulting scores, the score of any variable was identified and finally each of their rank determined. From the view of variables vulnerability rank of 1, accessibility to the building stories 2 and the building age 3” has the highest effect on the vulnerability of the city dwelling. Regarding the regression test, determination coefficient (R. Square) between two variables “qualitative and quantitative conditions of dwellings” in any urban zone and “vulnerability to the natural disaster” is %65, that is, “qualitative and quantitative conditions of dwellings” only verified %65 of the resulted variance in dependent variable and the reminded %35 are predictable by other factors. After studying total scores of the city zones, vulnerability rate was classified based on a range from 1 to 14 in which number 1 means the highest vulnerability and 14 the lowest vulnerability. Total scores of the whole variables were studied and each of the zones and scores were studied separately from 100 and then the zones ranked based on it. Zones 12, 3 and 4 have the highest rate of vulnerability and zone 5, 10, 7, 6, 13, 2, and 8 the moderate, respectively. IT means that with respect to the whole studied variables about natural disasters vulnerability, these zones are in planning priority about the crisis management. Conclusion In this survey, the following findings are to be studied and described: 1-when studying the urban vulnerability to the natural disaster, quality and quantity knowledge of the city dwellings has priority. 2-prioritising the urban zones from the viewpoint of quality and quantity vulnerability are possible using regression and Person analyses as well. 3-All of the variables studied were 24 ones classified to five basic elements. 4-The proportion and rank of any different variables on vulnerability rate of city dwellings were analysed. The results show that “accessibility to the building, accessibility to the building stories and building age” variables have the highest impact on the vulnerability rate of the city dwellings. 5- Finally, based on the whole variables analysis the vulnerability rate of dwellings obtained for the whole city and separated zones in which the zones 4, 3, 1 and 8 are the most vulnerable zones of the city, respectively.