فهرست مطالب

  • سال بیست و سوم شماره 4 (زمستان 1398)
  • تاریخ انتشار: 1398/09/10
  • تعداد عناوین: 7
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  • هاشم داداش پور*، محمد قضایی صفحات 1-35

    در مطالعات شهری، پدیده ها به طور عمده با یک نگاه کمی گرایانه مورد توجه قرار گرفته اند که در آن ها به مطالعه پدیده پرداخته شده و بررسی رابطه بین پدیده و سوژه فراموش شده است. این درحالی است که شهر و پدیده های آن دارای لایه های گوناگونی هستند که دستیابی به تمام آنها با بهره مندی از رویکرد کمی گرایانه امکان پذیر نیست. چراکه محققان کمی گرا به عنوان کسانی که نقش اصلی را در این پژوهش ها برعهده دارند، پدیده مورد نظر را تجربه و فهم نکرده اند و نتایج آنها به محاسبات کمی و آماری آنها محدود می گردد. حال آنکه فهم عمیق پدیده های شهری و پیامدهای آنها، جز با درک تجربه افرادی که آن پدیده را از نزدیک و برای سال ها درک کرده اند؛ امکان پذیر نیست. مبانی فلسفی و روش شناسی چگونگی درک این تجربه که به پارادایم پدیدارنگاری معروف است و  چگونگی به کارگیری آن در مطالعات شهری؛ هدف مطالعه حاضر است که بخش اول با بهره مندی از مطالعات کتابخانه ای و تحلیل اسنادی و بخش دوم با استفاده از مطالعات میدانی محقق شده است. نتایج نشان می دهد که پدیدارنگاری به دنبال کشف و توصیف پدیده ها با تکیه بر تجربه زیسته مردم است که این کار با بهره مندی از مطالعات میدانی و ابزار مشاهده مصاحبه نیمه ساختاریافته انجام می دهد. هم چنین در به کارگیری پدیدارنگاری برای بررسی تجربه زیسته مردم از پیامدهای زندگی در محله جداافتاده (رضویه) روشن گردید که افراد ساکن در این محله پیامدهای زندگی در این محله را در ابعاد متفاوت مدیریتی، اقتصادی، اجتماعی، کالبدی و عملکردی تجربه کرده اند و پیامدهای مدیریتی و اقتصادی را به عنوان علت سایر پیامدها می انگارند

    کلیدواژگان: پدیدارنگاری، تجربه زیسته، فضای نتیجه، پدیده شهری، جدایی گزینی
  • سحر درویشی، سید علی جوزی*، سعید ملماسی، سحر رضایان صفحات 37-61

    پروژه های سد سازی اثرات جدی بر پارامترهای محیط زیستی وارد می نماید. بنابراین ارزیابی ریسک محیط زیستی سد از مهمترین جنبه های مدیریت ریسک محیط زیستی در این پروژه ها می باشد. پژوهش حاضر با هدف ارائه مدل نوین ارزیابی ریسک محیط زیستی سدها در مرحله ساختمانی انجام شده است. بدین منظور، پس از شناسایی ریسک های محیط زیستی و بهره گیری از روشEFMEA ، عدد اولویت ریسک مربوط به هر یک از جنبه های محیط زیستی محاسبه و طبقه بندی شد. سپس جهت ارزیابی و اولویت بندی ریسک های محیط زیستی شناسایی شده از روش VIKOR استفاده گردید. نتایج نشان داد در روش EFMEA و با مقایسه اعداد ریسک محاسبه شده، ریسک آلودگی آب رودخانه بالارود با عدد اولویت ریسک 125 در اولویت اول قرار دارد. در روش VIKOR ریسک های آلودگی آب در شرایط توافق (بالا، متوسط، پایین) با وزن های (1.300، 1.000 و 0.700) به عنوان مهمترین ریسک شناسایی شد. در مقاله حاضر، استفاده از روش EFMEA و VIKOR در ارزیابی ریسک محیط زیستی سد مهمترین ریسک ها تعیین شد. مهمترین اقدام اصلاحی پیشنهادی  برای کاهش ریسک های محیط زیستی احداث و تکمیل تصفیه خانه فاضلاب برای واحدهای صنعتی می باشد.

    کلیدواژگان: پسا ارزیابی اثرات محیط زیستی، فاز ساختمانی، تکنیک EFMEA، تکنیک VIKOR.، ریسک محیط زیستی، مدل VIKOR، مدل EFMEA، سد
  • گلنار مخفی، کامران شایسته* صفحات 63-85

    شهر همدان در زمره شهرهای در حال توسعه چه از لحاظ صنعتی و چه از لحاظ گردشگری قرار دارد، لذا به منظور مدیریت بهتر و برآورد هزینه ها و امکانات، مدیران می بایست تصمیم گیری های خود را در این رابطه مبتنی بر ظرفیت برد قرار داده، تا در نهایت مبنای علمی و واقعی برای تصمیم گیری در رابطه با زیرساخت های شهری به دست آید. در این پژوهش از مدل عدد فشار ظرفیت برد شهری با استفاده از چهار نمایانه شامل تراکم ناخالص جمعیت، مصرف آب، تولید زباله و میانگین انتشار منواکسید کربن، به بررسی ظرفیت برد و میزان فشار وارد شده بر اکوسیستم شهری همدان استفاده گردید.با توجه به نقشه همپوشانی نمایانه ها می توان نتیجه گرفت در مجموع حدود 3/23 درصد نواحی دارای ظرفیت برد درجه 1 می باشد که اغلب در حاشه جنوب غربی شهر قرار گرفته اند و حدود 29 درصد دارای درجه ظرفیت برد 2 می باشندکه عمدتا در مناطق 3 و 4 قرار گرفته اند. 5/14 درصد نیز در درجه 3 ظرفیت برد قرار گرفته اند. حدود2/17 درصد  نواحی در ظرفیت برد آستانه می باشند. همچنین حدود 7/15 درصد دارای ظرفیت برد بحرانی هستند.

    کلیدواژگان: ظرفیت برد، شهر همدان، فشار بحرانی، آستانه، نمایانه، نماگر
  • حجت رضایی، مهران فاطمی*، محمدصادق طالبی صفحات 87-121

    امروزه مقوله امنیت شهری بویژه در فضاهای عمومی مانند پارک ها و فضاهای سبز که همواره مامنی برای آرامش، آسایش و تفریح شهروندان است، حائز اهمیت بسیاری است. در این زمینه  پژوهش حاضر با نظر به اهمیت و جایگاه بحث امنیت و احساس آن در عرصه های مختلف زندگی اجتماعی به عنوان مقوله بنیادی نیاز انسان، ضمن مشخص ساختن سطح احساس امنیت از نظر جامعه میزبان به مطالعه رابطه این موضوع با گذران اوقات فراغت شهروندان در سطح پارک های ناحیه ای شهر یزد پرداخته است. پژوهش حاضر از لحاظ روش تحقیق، توصیفی- تحلیلی و از نظر ماهیت، از نوع پژوهش های کاربردی است. نحوه گردآوری داده ها و اطلاعات نیز در پژوهش حاضر کتابخانه ای و میدانی است. جامعه آماری تحقیق را 384 شهروند یزدی تشکیل می دهند که به صورت تصادفی ساده در سطح پارک های ناحیه ای شهر یزد انتخاب گردیده اند. برای تجزیه وتحلیل داده ها از آمار توصیفی (شامل فراوانی، انحراف معیار و میانگین) و آمار استنباطی (آزمون اسمیرنوف، آزمون خی دو و ضریب همبستگی پیرسون) استفاده شده است. نتایج پژوهش نشان می دهد میزان احساس امنیت در پارک های ناحیه ای شهر یزد در سطح نسبتا مطلوبی (متوسط) قرار دارد.

    کلیدواژگان: احساس امنیت، اوقات فراغت، امنیت انتظامی، فضای سبز، پارک های ناحیه ای
  • محمود علیزاده، علی جعفر موسیوند*، سمیه سیما صفحات 123-145

    سری‏های زمانی داده‏های سنجش از دوری نقش مهمی در مدلسازی و پایش تغییرات عوارض و پدیده‏های سطح زمین در گذر زمان دارند. با این وجود، در حالی که سری زمانی تصاویر سنجنده های با قدرت تفکیک مکانی پایین (بیش از 100 متر از قبیل مادیس) در دسترس می‏باشند امکان تهیه سری زمانی منظم از داده‏های ماهواره‏های اپتیک با قدرت تفکیک مکانی مناسب (بهتر از 30 متر از جمله لندست) با توجه به پیکربندی مداری ماهواره‏ها و همچنین ابرناکی، بخصوص در مناطق مرطوب و مرتفع، چالشی اساسی در استفاده از این داده‏ها می‏باشد. یکی از روش های مرسوم برای برطرف ساختن این چالش، تولید تصاویر لندست-مانند با استفاده از ریزمقیاس‏نمایی تصاویر مادیس با استفاده از مدلهایی نظیر، مدل ESTARFM است. این تحقیق به ارزیابی کمی مدل ESTARFM به منظور ریزمقیاس‏نمایی تصاویر مادیس جهت تولید تصاویر لندست-مانند در مناطق غیرهمگن با استفاده از سه روش بازنمونه گیری تصویر، پوشش های زمینی مختلف و اختلاف زمانی بین تصاویر ورودی و شبیه‏سازی شده پرداخته است. نتایج نشان داد که استفاده از مدل با روش بازنمونه‏گیری خطی دوسویه با اختلاف جزیی عملکرد بهتری نسبت به سایر روش های بازنمونه‏گیری دارد. همچنین مدل ESTARFM قادر به تولید تصاویر لندست-مانند با RMSE بهتر از 0.02 بازتابندگی سطحی و ضریب تعیین بالاتر از 90 درصد در پوشش های مختلف زمینی می باشد. علاوه بر این، با افزایش اختلاف زمانی بین تصاویر ورودی و تصویر شبیه سازی شده دقت مدل به صورت معنی داری کاهش پیدا می کند.

    کلیدواژگان: ریزمقیاس سازی، ESTARFM، تصویر لندست-مانند، شبیه سازی بازتابندگی، تصاویر مادیس
  • ایرج اسدی، پریسا ملکی* صفحات 147-191

    هدف این تحقیق کشف ترجیحات مردم نسبت به فضاهای پیاده مدار و سنجش قابلیت پیاده مداری ذهنی و عینی و تبیین ارتباط مکانی آنها در محلات مناطق4، 8 و 13 شهر تهران است. این پژوهش از نظر روش شناسی در دسته تحقیقات توصیفی و اکتشافی قرار دارد که با رهیافت پژوهش های کمی انجام شده است. از داده های سرشماری، کاربری زمین، شبکه ارتباطی و داده های حاصل از نظرسنجی بهره گرفته شده است. جامعه آماری پژوهش حاضر کلیه جمعیت و همه محلات مناطق 22 گانه شهر تهران است. نمونه های آماری آن که به روش هدفمند انتخاب شدند شامل 31 محله هستند. یافته های این تحقیق در ارتباط با ترجیحات مردم نسبت به فضاهای پیاده مدار همسو با سایر تحقیقات بوده است و ساکنان شهر تهران در ارتباط با موضوع پیاده روی همانند مردمان سایر نقاط دنیا فضاهای دارای دسترسی مناسب به خدمات، امکانات و زیرساخت های مورد نیاز زندگی روزمره، محیط های ایمن، جذاب، سرزنده، شاداب، عاری از آلودگی و ترافیک، وجود فضاهای مناسب و تعریف شده برای پیاده روی را برای پیاده روی مناسب می دانند. یافته ها در ارتباط با شکاف بین پیاده مداری عینی و ذهنی نشان داد که به غیر از مولفه مکان هایی برای پیاده روی و دوچرخه سواری بقیه ابعاد مطالعه شده از جمله مدت زمان دسترسی به مغازه ها یا فروشگاه ها، تسهیلات و غیره، دسترسی به خدمات؛ خیابان های محله؛ محیط محله؛ امنیت ادارک شده از ترافیک؛ امنیت ادارک شده از جرم؛ و میران رضایت از محله در ارتباط با سنجش پیاده مداری ذهنی میانگین بالاتری در محلات با پیاده مداری عینی بالا در مقایسه با محلات با قابلیت پیاده مداری عینی پایین داشته اند.

    کلیدواژگان: پیاده مداری عینی، پیاده مداری ذهنی یا ادارک شده، واحد همسایگی، محله، تهران
  • راحله قره لو*، الهام قاسمی فر صفحات 193-212

    چکیدههدف از مطالعه حاضر پاسخ به این سوال است که تحت شرایط حدی دمایی، میزان تبخیر و تعرق در گستره ایران چه تغییراتی می کند. بدین منظور طی بازه زمانی 30 ساله مشخص شد که ماه ژانویه سال 2008 و ماه ژوئیه سال 2010، شرایط حدی دمایی سرد و گرم را ثبت کرده اند. سپس برای این دو ماه از داده های دمای هوای 55 ایستگاه، رطوبت خاک بازتحلیل شده NCEP/NCAR، دمای سطح زمین، پوشش گیاهی و تبخیر و تعرق سنجنده مادیس با وضوح فضایی پنج کیلومتری بهره برده شد. ابتدا ریسک رخداد دماهای حدی این دو ماه با توزیع خطر تجمعی و گامبل مشخص شد و نتایج نشان داد رخداد دماهای حدی بالای 50 درجه در ماه ژوئیه 06/0 و دماهای بالای 22  درجه در ماه ژانویه 008/0 است.  همچنین احتمال رخداد دماهای بالای 5 درجه در ماه ژانویه 50/0 است. بطور کلی و بدون در نظر گرفتن آستانه دمایی،  در هر دو ماه ارتباط منفی بدست آمد اما در ماه ژانویه بدلیل ثبت دماهای بیش از 5 درجه به احتمال رخداد 50 درصد، ارتباط منفی ضعیف نزدیک به صفر مشاهده شد. عامل رطوبت نشان می دهد که هر دو ماه از آستانه رطوبتی مشخصی بدلیل سرمایش و گرمایش بیش از حد رنج برده اند و هرگاه محدودیت رطوبت وجود داشته باشد این ارتباط منفی است در نتیجه توجیه کننده ارتباط کلی منفی (بدون در نظر گرفتن آستانه دمای هوا) ماه ژانویه نیز می باشد.

    کلیدواژگان: تبخیر و تعرق، دماهای سطحی حدی، پوشش گیاهی، سنجنده مادیس
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  • Hashem Dadashpoor*, Mohammad Ghazaie Pages 1-35
    Introduction

    Urban studies have often investigated phenomena through quantitative approaches. They have just studied the urban phenomena solely, and their relationships with the subjects have been discounted. That is while urban, and its phenomena usually have different layers which cannot be understood only through quantitative approaches. Because, quantitative researchers who play the most prominent role in these studies, have not experienced and understood the phenomenon and their results are often restricted to their statistical and quantitative analysis. While the deep understanding of urban phenomena and their consequences is only possible through understanding the experiences of those who have experienced and understood those phenomena for many years. The philosophical and methodological literature of understanding these experiences which is called phenomenography and the way it can be used in urban studies are the aims of the current study.

    Methodology

    Thus, to understand the philosophical, epistemological and methodological principles of phenomenography library research and documentary analysis has been used and for the application of phenomenography in urban studies a field study has been conducted. To do this, at first, one of the segregated neighbourhoods (Razavieh) of Tehran as the capital of Iran has been selected, and then through a phenomenographic paradigm, it has been tried to understand how residents in that neighbourhood experience segregation and how segregation has affected their quality of life. Consequently, an unstructured interview has been done by 23 of residents through a snowballing and purposeful sampling. Interviews have been recorded, and then they have been typed and finally through the phenomenographic strategy which has got seven different steps, the manuscripts have been analysed.

    Results and discussion

    The documentary analysis’s results indicate that qualitative research methodology and phenomenography can be considered as an indispensable methodology in urban studies because phenomenography aims to explore and describe phenomena with an emphasis on individuals’ lived experiences. With regarding the fact that phenomenographer should make friend with interviewee he/she would be able to get the sheer feeling of residents about a specific phenomenon which can help experts avoid from skin-deep decision making and face them with the reality what is usually hindered from them through quantitative methodologies. It should be taken into account that a phenomenographer usually reflects individuals’ feelings and they usually try not to make interventions while they are analysing the manuscripts.
    Results which have been gathered through field study indicate that consequences which are imagined for living in a segregated neighbourhood and are usually extracted from quantitative analysis, are far beyond that we may imagine. Segregation’s consequences affect individuals’ lives through managerial, economic, social, physical and functional dimensions. In case of functional consequences, results indicate that residents’ lives are accompanied by a feeling of inequality. In case of physical features, negative consequences could be considered in three main groups which are the neighbourhood's distance from city centre, the quality of neighbourhood's landscape and urban fabrics. Social negative consequences could be divided into four main categories which are related to the impacts that living in a segregated neighbourhood has on demographics, society, households, and Individuals. In case of economic, residents’ job opportunities are affected, and it usually leads to their inability for affording their lives. Moreover, managerial consequences usually increase the distance between residents and managers which corruption and the lack of sense of belonging to the neighbourhood and its people are among the most significant ones.

    Conclusion

     In general, it can be declared that reaching to a pure understanding of urban phenomena especially those which are more complex, needs investigating of residents’ lived experiences what has been considered less in recent studies not only in Iranian contexts but also in all over the world. Phenomenography which makes understanding individuals’ lives possible is one of the qualitative ways which here is suggested. It can be used for those phenomena which are complicated and are dealing with individuals. Since it studies the relationships between the phenomenon and individuals, it can provide sheer results of what is going on. It should be taken into consideration that phenomenography is different from phenomenology which is more famous among scholars. With regarding these features which were counted for phenomenography and with considering the fact that urban phenomena are thoroughly in contact with individuals; it can be understood that phenomenography could be really helpful because it considers the relationship between the phenomenon and the subject rather considering the phenomenon solely. Through using phenomenography for investigating the negative consequences of living in a segregated neighbourhood not only it has been revealed that consequences are way more than those which are extracted through quantitative analysis, but it has been understood that residents consider managerial and economic consequences as the main ones and they believe that these consequences give rise to other ones. Moreover, based on the lived experiences it has been revealed that social consequences of segregation are more profound than the rest.

    Keywords: Phenomenography, Lived experience, Outcome space, Urban phenomenon, Segregation
  • Sahar Darvishi, Seyed Ali Jozi*, Saeed Malmasi, Sahar Rezaian Pages 37-61

    Dam construction and development projectshave serious effects on environmental parameters. Therefore, environmental risk assessment of the dam is one of the most important aspects of environmental risk management in these projects. The purpose of this study is to provide a new model for assessing the environmental risks of dams during the construction phase. To this end, after identifying environmental risks and using the EFMEA method, the RPN for each environmental aspect was calculated and classified. The VIKOR method was used to assess and prioritize identified environmental risks. The results show that in the EFMEA method and by comparing the calculated risks, the risk of pollution of the Balarood river with, RPN 125 is the first priority. In the VIKOR method, the risk of water pollution (high, medium, low) with weight (1,300, 1,000 and 0,700) was identified as the most important risk. In this paper, EFMEA and VIKOR methods are used to assess the environmental risk of the dam. The most important modified action to reduce environmental risks is the construction and completion of wastewater treatment plants for industrial units.

    Keywords: post environmental impact assessment, Construction phase, EFMEA technique, VIKOR technique, Environmental Risk, VIKOR model, EFMEA model, Dam
  • Golnar Makhfi, Kamran Shayesteh* Pages 63-85
    Introduction

    Hamedan is among the developing cities both in terms of industry and tourism, therefore, in order to better manage and to estimate costs and facilities, and on the other hand, due to the growing urbanization rate and the increasing population of the city, managers should make their decisions based on the carrying capacity of the city.

    Methodology

    In this research, based on Urban Carrying Capacity load Number Model, and Using four Indicators including population density, water consumption, waste production, and average carbon monoxide emissions, the Carrying Capacity and the amount of pressure imposed on the urban ecosystem of Hamadan were investigated.

    Results and discussion

    According to the results, 23.3% of the study area, with the first-class of Carrying Capacity are located in the southwest of the city. 29 % have grade 2 of Carrying Capacity, often located in areas 3 and 4. 14.5% have been ranked 3. About 17.2% of the areas are in the Carrying Capacity of the threshold. Also, about 15.7 percent have a critical Carrying Capacity and it can be concluded that no place in Hamadan has been in the desired state.

    Conclusion

    Forasmuch as no region is in optimal condition and about 32% of the area is past the limit of the carrying capacity threshold, Therefore, the situation in the city of Hamedan seems to be Instability and the conditions will eventually lead to a reduction in the urban carrying capacity.

    Keywords: Carrying Capacity, Hamadan City, Critical Pressure, Indicator, Thresholds
  • Hojjat Rezaie, Mehran fatemi*, Mohammad Sadegh Talebi Pages 87-121
    Introduction

    The existence of security in a place of recreation is considered as one of the most important parameters in decision making for visiting and spending leisure time in that location. On the other hand, the lack of security not only does not lead people to public places, promenades and walkways, but because of the lack of presence and isolation of these places, crime and its dimensions are spreading in these places, and therefore it is said that between security and leisure mutual and complementary relationship exists. Therefore, considering the importance of the subject, this study aims to investigate the relationship between the sense of security and spending leisure time in the public spaces of Yazd (regional parks in Yazd city). Because parks are one of the most prominent public spaces in the city and the most important components of the urban, human and natural body, which, taking into account the conquest of the green space element, attract the population and provide the ground for social interaction and spending leisure time in terms of recreation, entertainment, sports, Studying and relaxing nature-based recreations.

    Methodology

    The present research is descriptive-analytic in terms of applied purpose and is based on observation, interview and questionnaire. The dominant view in the methodology of the present study is the systematic approach based on the structural-functional approach, which is carried out in a deductive-inductive method, considering the combination of natural formations (green spaces-parks) and human formations (security and Feeling of security). To collect information in this study, two methods of library and survey using a questionnaire have been used. Its content validity has been confirmed by the opinion of 10 specialists in urban planning, social sciences and law enforcement and necessary corrections. The population of the study consisted of citizens of Yazd city, which according to the Cochran formula, 384 citizens at 0.05% error rate were randomly selected in 7 parks under study for two consecutive weeks. Data analysis in this research has been carried out in two descriptive and inferential sections. In the inferential part of the test, Smirnov test, Chi square test and Pearson correlation coefficient have been used to answer the research questions. It should be noted that in this study, in order to measure the level of feeling of security and to clarify its relationship with spending leisure time in the parks, according to the opinion of the panel of 10 experts from among the security dimensions in view of the impact of the high level of human, financial, and moral security And law enforcement on the mental and psychological health of citizens in the city; these four dimensions of security have been selected for research.

    Results and discussion

    The results of the Smirnov test at 99% confidence level show, firstly, the data are normal and then indicate that the sanity, financial, ethical, and law enforcement in the parks are inappropriate. Because Z score has been evaluated, four security dimensions below the average level have been evaluated. Among the four dimensions of the security feeling studied, law enforcement with a 3.11 test statistic at the highest level and moral security with the 2.98 statistics was at the lowest level.The results of the general Chi-square test showed that the society of citizens, respectively, had a sense of security with a 255,487 statistics, a security sense of 249,321, a sense of moral security with a 229,189 statistics, and a sense of financial security of 220,979 with a statistically significant effect on increasing leisure time of citizens In the Regional parks in the Yazd city.The results of Pearson correlation coefficient at 99% confidence level for the citizens of the community indicate that there is a direct relationship between the feeling of security and the leisure time of citizens in the parks. The correlation coefficient between the sense of human security and the leisure time of citizens equal to 0.953, between the feeling of financial security and spending leisure time 0.712, between the sense of moral security and spending leisure time 0.806 and between the sense of security and leisure time spent 0.950 was assessed. This the coefficients show the severity of the relationship between these two variables and the impact of the feeling of security on the leisure time of citizens in the parks.

    Conclusion

    The results of this study indicate that the safety of the studied parks is relatively desirable and not quite desirable. According to the results, security at the highest level of moral and moral security has been at the lowest level. There is a significant safety effect on leisure activities in Yazd parks. Among the dimensions examined, the feeling of personal safety has the greatest impact on the quality of leisure time and the feeling of financial security. Finally, it was found that in the parks in Yazd there is a significant and direct relationship between safety and leisure time; it was also found that there was a significant relationship between the four security dimensions studied, and these four dimensions Have a positive and significant impact on each other, and as the community of citizens has pointed out, security law enforcement plays a more important role in creating the moral, financial, and moral security. Therefore, it is suggestes that through the provision and provision of military and security infrastructures at the level of parks in the region, such as the establishment of regular military, security and ethical patrols, the establishment of a police station, and the continued establishment of park ranger , will enhance the sense of security in urban parks in Yazd.

    Keywords: Feeling of security, free time, Security guard, green space, Regional parks
  • Mahmood Alizadeh, Ali Mousivand*, Somayeh Sima Pages 123-145

    Satellite time series data play a key role in characterizing land surface change and monitoring of short and long-term land cover change processes over time. While coarse spatial resolution optical sensors (e.g. MODIS) can provide appropriate time series data, the temporal resolution of high to intermediate spatial resolutions sensors (1-100 m e.g. Landsat) does not allow for having temporally frequent measurements because of the orbital configuration of such sensors and cloud contamination. A promising approach for addressing this challenge and producing Landsat-like imageries is the blending of data from coarse spatial resolution sensors like MODIS. Among different approaches proposed in the literature, the ESTARFM model has been reported to outperform other models in generating Landsat-like imageries with reasonable accuracy over heterogeneous areas. Despite the large body of studies implementing ESTRAFM for downscaling MODIS data, quantitative evaluation of the model under different conditions has not yet been investigated. This study quantitatively evaluates model performance over different land cover types, resampling methods and time-difference analysis between input and synthetic images. The results demonstrated that employing bilinear resampling in the ESTARFM produces results slightly better than nearest neighbor and cubic resampling methods. Moreover, the ESTARFM model accurately predicts Landsat-like surface reflectance images with RMSE better than 0.02 and correlation more than 90% over different land cover types. However, the model performance significantly degrades as the time difference between the input and synthetic images increases.

    Keywords: ESTARFM, downscaling, Landsat-like imageries, MODIS data, Reflectance simulation
  • Iradj Asadi, Parisa Maleki* Pages 147-191
    Introduction

    A large number of researches demonstrated that built environment attributes affect the walking and cycling for transportation (Ewing & Cervero, 2010; Bauman et al., 2012). Studies examining the potential effect of the built environment on physical activity have employed objective and/or perceived (self-report) measures to assess characteristics of the neighborhood environment. Findings illustrated people who live in neighborhoods with traditional or walkable designs report about 30 minutes more walking for transportation each week and more total physical activity, compared to those who live in neighborhoods with less walkable suburban designs (Frank, et al., 2006). Therefore, the association between the built environment and walking activity are complicated due to spatial heterogeneity, self-selection issues such as attitudes and perceptions on walking behavior, and methodological differences (Lee, et al., 2017). Some evidence shows that residents’ self-reports of their neighborhood environment may be less revealing than are objective assessments. However, other studies suggest that perceived neighborhood environment exerts a unique effect and may be a more telling indicator for individual health than objective neighborhood characteristics (Wen et al., 2006). So, the aim of this research is discovering the preferences of the residence towards the walkable spaces and explaining spatial association of the perceived and objective measures of neighborhood walkability in district of 4, 8 and 13 of Tehran.

    Methodology

    This research is a descriptive and exploratory research that has been conducted with quantitative research approach. In this regard, GIS software were used to mapping the neighborhood walkability criteria. Network analyst functions, also, was used in order to service area determination and accessibility to public services. Exploratory factor analysis and multiple regression were cooperatively employed with regard to reduce the set of variables and extract variables that explain the objective and perceived measures of neighborhoods walkability at a 95% confidence interval in Tehran metropolitan. In relation to perceived measure of neighborhoods walkability, we used the standard questionnaire developed by Saelens et al. (2002), as well as Cerin et al. (2006), has been developed as Neighborhood Environment Walkability Scale (NEWS). The questionnaire has the following dimensions: Time taken to get from residence home to the nearest businesses or facilities, Access to services, Streets condition or quality in the neighborhood, Places for walking and cycling, Neighborhood surroundings, Safety from traffic, Safety from crime neighborhood satisfaction. In the present study for each neighborhood, walkability index, which is the sum of the standard Z score of four urban form metrics, is defined as a function of net residential density (ratio of the number of residential units to residential areas in each neighborhood per hectare), sum of the ratio of floor area of retail units to their parcels in each neighborhood, Land-use mix index (entropy coefficient) and street connectivity (Number of intersections with 3 or more legs per km2). Also, census data, land use and road layers and survey data were used. The statistical population of the present study is the population of all districts of the 22 districts of Tehran. The statistical samples which selected by purposeful method were 31 neighborhoods.

    Results and discussion

    Findings revealed that the gap between the objective and the perceived walkability, except the component of walking and cycling places, the rest of the studied dimensions, including the time of access to shops or stores, facilities, etc., access to services; neighborhood streets; neighborhood environment; perceived security of traffic and crime; and the satisfaction of the neighborhood in relation to subjective pedestrian assessment have a higher mean in neighborhoods with high objective walkability compared to those with low walkable neighborhoods. Research findings in regard to the people preferences about the walkable spaces are in line with other studies. Residents of our case study in connection with the issue of walking, as well as people from other parts of the world, prefer spaces with appropriate access to services, facilities and infrastructure needed for everyday life, and safe, attractive, lively and free of contamination and traffic environments as well as well-defined spaces for walking. The point that needs to be mentioned is the population density, the density of residential units, as well as the density of activities (commercial and service as well as offices or administrative activities). In most previous investigations, mainly in link to walking, built environment with urban sprawl form are compared to more compact cities or so-called smart cities with mixed and diverse land uses, and the result is typically that urban environments which have a dense and smart urban form that are high in density of population, activity and residential are reported proper for walking behavior. In this regard, although the urban form of the studied neighborhoods of this research compared to many previous case studies in terms of those variables, is still more compact, according to the participants’ opinion, they prefer to walkability of their residential spaces, neighborhoods that have diverse land uses (cloth stores, food markets, supermarkets, juices and ice cream shops, home appliances malls and etc.), as well as green and open spaces and environments that have more attractive facets.

    Conclusion

    In order to achieve the appropriate developmental model to increase the subjective and objective walkability of urban neighborhoods, some steps must be taken to increase the green and public open spaces and redistribute the land uses in accordance with the urban smart growth pattern, by through less dependence on the personal car usage, many challenges of Tehran metropolitan will reduce in line with sustainable development.

    Keywords: Perceived walkability, Objective walkability, neighborhood, Quarter, Tehran
  • Raheleh Ghareloo*, Elham Ghasemifar Pages 193-212
    Introduction

    According to the Intergovernmental Panel on Climate Change (IPCC) in 2012, globally, a large number of climatic events have increased in recent decades such as extreme temperatures, floods and etc. That’s the number of warm days and nights has increased, and climate models predict extreme temperature by the end of the 21st century (IPCC, 2012). Ecosystems, the global economy and public health are highly vulnerable to these extreme events, especially extreme temperatures (Kunkel et al., 1999). Generally, in Iran, the regionalization of extreme temperatures has been studied. For example, Rezaei et al. (2015) examined the extreme temperatures in two months with extreme temperature and identified different areas for Iran. Masoudian and Darand(2008) also studied extreme cold temperature in Iran and regionalized six areas for Iran. Considering the studies that indicates the occurrence of extreme temperatures for different parts of the world, it is interesting to note the role of these extreme temperatures on evapotranspiration difference between extreme cold and warm temperatures. Evapotranspiration is the water loss from the ground to the atmosphere and defined as a key process in the water cycle (Wang and Dikeson, 2012), which is related to plant growth (Alberto et al., 2014), drought (Anderson et al, 2011), greenhouse gas (Balogh et al., 2015) and climate change (Abtew and Melesse, 2012). The purpose of this study is to answer the question of what is the changes in evapotranspiration under extreme temperature conditions in Iran.

    Methodology

    For answer the research’s question it found clearly that January 2008 and July 2010 had recorded extreme cold and warm temperatures during the period of 30 years. For these two months, 55- air temperature stations data, soil temperature from NCEP / NCAR reanalysis database, land surface temperature (LST), vegetation cover, and evapotranspiration from Moderate Resolution Imaging Spectroradiometer (MODIS) were utilized in five kilometer or 0.05 degree resolution. At first, the risk of occurrence of the extreme temperatures was determined by the distribution of the cumulative risk and the Gumbel distribution during these two months. The land surface temperature data product (LST) namely MOD11C3, which has 0.05 degrees (approximately 5 kilometers or 5600 meters) and with a monthly and global time scale was used. To investigate the changes in evapotranspiration, the MODIS evapotranspiration product namely MOD16 was utilized (Mu et al., 2012). The data is available on an annual, eight-day and monthly basis. In this process, evapotranspiration is provided globally and with a resolution of one kilometer covering 109 million square kilometers of the land’s surface. The algorithm used the Penman-Monteith equation to produce this product (Monteith, 1965). Then for the analysis Pearson’s correlation and coefficient of determination were used. 

    Results and discussion

    The results showed that the occurrence of extreme temperatures above 50 degrees Celsius is 0.06 in July and temperatures higher than 22 degrees Celsius is 0.008 in January. Also, the probability of temperature higher than 5 degrees Celsius is 0.50 in January. Correlations results indicated that the two factors of energy (air temperature) and soil moisture are the main controller of the relationship between these parameters (LST and evapotranspiration), so that when the air temperature was above 5 degrees Celsius, a significant negative correlation was observed (-0.24 in January and -0.64 In July) and when the air temperature is below than 5 degrees, it will be positive (0.23 in January). Generally, regardless of the threshold, a negative correlation was obtained for every two months, but a weakest negative correlation (close to zero) was observed in January, due to the recording of temperatures exceeding 5 ° C with an incidence of 50%. The humidity factor shows that every two months have suffered from a certain moisture threshold due to extreme cold and warm temperatures, and if there is a moisture limit, this relation will be negative, thus it’s a determination factor for the overall negative relationship (regardless of the temperature threshold) in January.

    Conclusion

    The extreme temperatures showed the highest impact on evapotranspiration so that air temperature was identified as a trigger for the relationship between LST and evapotranspiration.

    Keywords: evapotranspiration, extreme LST, NDVI, soil moisture, MODIS