تحولات کالبد شهر و بازتاب حرارتی آن بررسی موردی: اصفهان
Urban Change and Its Thermal Impacts Case Study: Isfahan
اشتراک گذاری
اشتراک در شبکه های اجتماعی :
گزارش خطا
گسترش شهرها و افزایش شهرنشینی تبعات بسیاری به همراه دارد. از آن جمله افزایش دمای بسیاری شهرها نسبت به حوزههای پیرامونی آنها است. این افزایش دما تبعاتی از تهدید سلامت شهروندان بهدلیل افزایش تنش حرارتی و آلودگی گرفته تا بازتاب اقتصادی بهدلیل افزایش نیاز به انرژی را دربر میگیرد و ضرورت تحقیق را پررنگ مینماید. طراحی شهری میتواند با ابزارهای متعدد از جمله کالبد شهری در تعدیل حرارتی غیرفعال تأثیرگذار باشد. این پژوهش با تأکید بر شاخصهای طبیعی و کالبدی به ریشهیابی ارتباط آنها و حرارت پرداخته و به مقایسه سالهای 2000 و 2014 اصفهان میپردازد. هدف اصلی پژوهش نشان دادن ارتباط تحولات شهری و افزایش دمای سطح و دمای هوا است. مقایسهها بر تنش حرارتی بازتاب شده از دمای سطح مبتنی است و شناسایی حوزههایی با بیشترین تغییر دمای سطح و ریشهیابی علل آن در این پژوهش صورت گرفته است. بهعلاوه در مقایسه گرمترین و خنکترین حوزهها از دادههای برداشت شده میدانی نیز استفاده گردید. این تحقیقات تأثیر خشکسالی و کاهش سبزینگی را هم بر دمای سطح و هم بر دمای هوا نشان میدهد و یکی از مهمترین عوامل مؤثر بر دمای هوا را سایهاندازیها و ضریب آسمان قابل رؤیت برپایه محصوریت کالبدی و فضای سبز معرفی مینماید.
Increased speed of life has changed the cities in different ways and has caused many consequences. One of them is heating intensity in the cities compared with their surroundings. Heating stress has some different impacts on residents, from residents’ health to economic consequences. Their health is in danger because of thermal stress, greenhouse gasses, and pollution, and there would be economic consequences upon people’s life, due to increasing energy consumption. Thus, controlling urban temperature is an important factor in the design process. Urban design with its tools including urban morphology can play an imperative role in the passive cooling design. Isfahan has been selected with regard to its climate and hot summers, its urban changes in recent years and droughts. The thermal impact of changing urban morphology is an object of this study. Two phases have been designed in this study. In the first phase, comparison of land surface temperature, LST, were conducted in years 2000 and 2014 in Isfahan. In this regard, satellite images of Landsat 7, ETM in Envi 4.7 were used. Six districts were selected with maximum differences in LST between the years of 2000 and 2014. The changes in the natural environment have been studied by urban greenery and water, and built environment including sky view factor, closeness and materials. In the second phase of the study, a field measurement was conducted in the coolest and the hottest districts. Selecting a base point in each area and comparing the measurement points with this reference point illustrated the morphological impact in each point. The increasing of 562 ha of the hot spaces of the city (>40°C) in 14 years of study illustrated that the city had clearly become warmer. Furthermore, the maximum alterations were seen in urban greenery (NDVI) and water, which emphasizes their impact on heating of the city. Due to drying up the main river of the city, i.e. Zayandeh Rood, and its branches, i.e. Madies, the thermal surface has increased dramatically. Besides, decreased water has affected different parameters in thermal comfort. Moreover, 14% decrease of urban greenery has an important role in increase of surface and air temperature. The consequence of changing urban greenery and its thermal impact in some districts with more vegetation in 2014 than 2000 and some districts with less greenery have been approved in this study. In-built environment parameters, the vacant land or a large areas of asphalt like large squares were two important factors, especially in surface temperature. These impacts in the historical district of Isfahan, created very hot points in this areas. Inferior materials for insulations were another factor which has affected the LST. Sky view factor as an undeniable factor in thermal comfort has been changed between 2000 and 2014. Although in some districts the SVF has decreased, mainly by increasing the height of buildings, in other districts the SVF have increased due to cutting the shading trees. Decreasing SVF especially by shading trees is recommended in this study. The most important result of this study is showing the impact of urban designer’s role in heat mitigation in the cities by controlling urban morphology.
(2.2 مگابایت)
دانلود مقاله
مشخصات مقاله
- Ai, Z. & Mak, C. (2015) "From street canyon microclimate to indoor environmental quality in naturally ventilated urban buildings: issues and possibilities for improvement," Building and environment, 94, 489-503.
- Akbari, H.; Pomerantz, M. & Taha, H. (2001) "Cool surfaces and shade trees to reduce energy use and improve air quality in urban areas," Solar energy, 70(3), 295-310.
- Buyadi, S. N. A.; Mohd, W. M. N. W. & Misni, A. (2013) "Green Spaces Growth Impact on the Urban Microclimate," Procedia-Social and Behavioral Sciences, 105, 547-557.
- Correa, E.; Ruiz, M. A.; Canton, A. & Lesino, G. (2012) "Thermal comfort in forested urban canyons of low building density. An assessment for the city of Mendoza, Argentina," Building and environment, 58, 219-230.
- Dow, C. L. & DeWalle, D. R. (2000) "Trends in evaporation and Bowen ratio on urbanizing watersheds in eastern United States," Water Resources Research, 36(7), 1835-1843.
- Fouillet, A.; Rey, G.; Laurent, F.; Pavillon, G.; Bellec, S.; Guihenneuc-Jouyaux, C.; ... & Hémon, D. (2006) "Excess mortality related to the August 2003 heat wave in France," International archives of occupational and environmental health, 80(1), 16-24.
- Givoni, B. (1998) Climate considerations in building and urban design, John Wiley & Sons.
- Grimmond, C. & Oke, T. R. (1999) "Heat storage in urban areas: Local-scale observations and evaluation of a simple model," Journal of Applied Meteorology, 38(7), 922-940.
- Hajat, S.; Kovats, R. S. & Lachowycz, K. (2007) "Heat-related and cold-related deaths in England and Wales: who is at risk?" Occupational and environmental medicine, 64(2), 93-100.
- Jacob, D. J. & Winner, D. A. (2009) "Effect of climate change on air quality," Atmospheric Environment, 43(1), 51-63.
- Kolokotroni, M.; Giannitsaris, I. & Watkins, R. (2006) "The effect of the London urban heat island on building summer cooling demand and night ventilation strategies," Solar energy, 80(4), 383-392.
- McKibben, B. (2007) "Climate Change 2007: The Physical Science Basis: Summary for Policymakers. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change," New York Review of Books, 54(4), 44.
- Nations, U. (2015) Adoption of Paris agreement, Framework convention on climate change (FCCC 12-12). Paris.
- Oke, T. R. (1987) Boundary layer climates, Vol. 5, Psychology Press.
- Rizwan, A. M.; Dennis, L. Y. & Chunho, L. (2008) "A review on the generation, determination and mitigation of Urban Heat Island," Journal of Environmental Sciences, 20(1), 120-128.
- Santamouris, M. (2013) Energy and climate in the urban built environment, Routledge.
- Schwarz, N.; Schlink, U.; Franck, U. & Großmann, K. (2012) "Relationship of land surface and air temperatures and its implications for quantifying urban heat island indicators—an application for the city of Leipzig (Germany)," Ecological Indicators, 18, 693-704.
- Shashua-Bar, L. & Hoffman, M. (2000) "Vegetation as a climatic component in the design of an urban street: An empirical model for predicting the cooling effect of urban green areas with trees," Energy and buildings, 31(3), 221-235.
- Shashua-Bar, L.; Pearlmutter, D. & Erell, E. (2009) "The cooling efficiency of urban landscape strategies in a hot dry climate,"Landscape and Urban Planning, 92(3), 179-186.
- Shen, T.; Chow, D. & Darkwa, J. (2013) "Simulating the influence of microclimatic design on mitigating the Urban Heat Island effect in the Hangzhou Metropolitan Area of China," International Journal of Low-Carbon Technologies, ctt050.
- Srivanit, M. & Kazunori, H. (2011) "The Influence of Urban Morphology Indicators on Summer Diurnal Range of Urban Climate in Bangkok Metropolitan Area, Thailand," International Journal of Civil & Environmental Engineering, 11(5), 34-46.
- Takebayashi, H. & Moriyama, M. (2007) "Surface heat budget on green roof and high reflection roof for mitigation of urban heat island," Building and environment, 42(8), 2971-2979.
- Weaver, C.; Cooter, E.; Gilliam, R.; Gilliland, A.; Grambsch, A.; Grano, D.; ... & Winner, D. (2009) "A preliminary synthesis of modeled climate change impacts on US regional ozone concentrations," Bulletin of the American Meteorological Society, 90(12), 1843-1863.
- Wong, S. L.; Wan, K. K.; Li, D. H. & Lam, J. C. (2010) "Impact of climate change on residential building envelope cooling loads in subtropical climates," Energy and buildings, 42(11), 2098-2103.
- Yuan, F. & Bauer, M. E. (2007) "Comparison of impervious surface area and normalized difference vegetation index as indicators of surface urban heat island effects in Landsat imagery," Remote Sensing of Environment, 106(3), 375-386.
- Zhang, Z.; Lv, Y. & Pan, H. (2013) "Cooling and humidifying effect of plant communities in subtropical urban parks," Urban forestry & urban greening, 12(3), 323-329.
مسابقات
جوایز
نشریات
http://aup.journal.art.ac.ir
