بررسی تاثیر پارامترهای محیطی و جمعیتی بر توزیع مکانی دمای سطح کلان‏شهر تهران با تلفیق مدل‏‏ های آماری و مدل تک ‏پنجره

امروزه یکی از مهم‏ترین معضلات زیست‏محیطی در کلان‏شهرها افزایش دمای سطح و در نتیجه افزایش شدت جزیره حرارتی شهری است. هدف از این پژوهش بررسی تاثیر پارامترهای محیطی و جمعیتی در توزیع مکانی دمای سطح کلان‏شهر تهران است. بدین منظور، از ده تصویر ماهواره‏ای لندست مربوط به سال‏های 2010 و 2011 برای استخراج نقشه‏های پارامترهای محیطی، کاربری پوشش سطح زمین، و دمای سطح زمین استفاده شد. برای طبقه‏بندی کاربری پوشش سطح زمین از روش بیشترین شباهت و برای محاسبه دمای سطح از مدل تک‏پنجره استفاده شد. همچنین، برای مدل‏سازی پارامترهای محیطی از شاخص‏های ndvi، ndwi، و ndbi استفاده شد. سرانجام، برای بررسی تاثیرگذاری پارامترهای جمعیتی و محیطی بر توزیع دمای سطح از تحلیل‏های آماری استفاده شد. نتایج پژوهش نشان‏دهنده آن است که ضریب همبستگی بین میانگین شاخص‏های ndvi، ndwi، و ndbi با دمای سطح به‏ترتیب 0.89، 0.8، و 0.82 است. میانگین دمای سطح برای کاربری‏های ساخته‏شده، فضای سبز، بایر، و آب به‏ترتیب 312.16، 309.36، 317.36، و 303.86 است. نتایج نشان داد که با افزایش مقادیر شاخص‏های ndvi، ndwi، و ndbi دمای سطح به‏ترتیب کاهش، کاهش، و افزایش می‏یابد. همچنین، ارتباط مستقیم با ضریب همبستگی 0.65 بین تراکم جمعیت و میانگین دمای سطح هر منطقه وجود دارد.

Investigating the Effects of Environmental and Demographic Parameters on the Spatial Distribution of Surface Temperature of Tehran by Combining Statistical and MonoWindow Models

IntroductionOne of the emerging environmental hazards arising from the expansion of urbanization is the phenomenon of urban heat island. Urban heat island is a phenomenon in which urban areas experience warmer temperatures than the surrounding countryside. This phenomenon has been studied and recorded in the world over 150 years ago and generally, along with natural vegetation changes; It usually can appear in impenetrable surfaces such as pavement streets, cement, asphalt, concrete, etc. The effects of urban heat island on human life include increased energy consumption due to increased demand for building cooling during the warm seasons, increased heat stress and reduced staffing efficiency, increased water consumption and increased urban air pollution. Also, UHI has caused a change in the urban and global climate. Given the increase in population, the importance of energy and the issue of global warming will be increased over the coming decades.The Tehran city is the capital of Iran and center of economic activity in the country. Each year, a large number of different provinces migrate to the province to work, which will destroy the green space and increase population in the city. This causes a lot of problems including increasing the surface temperature. Therefore, the aim of this paper is to investigate the effect of demographic and environmental parameters on the spatial distribution of Tehran’s metropolis surface temperature.Materials and methodsIn this study, the Landsat 5 satellite image of TM sensor has been used for the studied area. In order to complete input parameters for mapping surface temperature using satellite imagery of meteorological data, and for providing field samples, we used Google Earth images and topographic maps of Iran Cartographic Center to provide surface weather maps.At first, the preprocessing steps were applied to prepare images including atmospheric correction. Then, the images were classified using a Maximum Likelihood and were classified into four landuses, built up, fallow, water and green space. After classification, each of the images was categorized using precision classification controls. In the next step, using the Mono Window algorithm, surface temperature was obtained for each image.Results and discussionGiven the existing landuses, the area was classified by 4 types of builtup, green space, bare land, and water using the supervised classification method. The area builtup, green space, bare land and water are 37061.46, 9512.91, 11470.05 and 44.91 ha, respectively. The most of the landuse is built environment. The surface temperature values here are ranged from 294 to 328 degrees Kelvin. The lowest average temperature is for water use and natural areas such as green spaces, forest and urban parks, while the maximum temperatures are in shallow land and impenetrable lands such as asphalt, street paving and other Manmade coatings, as well as industrial and commercial lands, and the surfaces of residential and transportation facilities.Based on the total population of Tehran in 2011, the districts of 21, 22, 12 and 9 are considered as the main core of the urban heat island among the low population areas of Tehran. Due to various landuses (industrial, commercial, transportation, etc.), low population density in these areas appears natural. While the urban heat island in these areas is mainly resulted from industrial activities, airports, transportation, commercial land use, and bare land degradation. Map of surface temperature and population distribution in different regions of Tehran show that the regions with high temperatures in districts of 4, 5, 15, 2 and 14, have a high population density. Although these areas are not among the main heat islands in Tehran; however, due to high population density, high traffic volume, and air pollution from these areas is endangered by the emergence and expansion of urban heat islands. ConclusionThe purpose of this research is to investigate the effect of demographic and environmental parameters on the spatial distribution of Tehran’s surface temperature. The results of the study indicate that heterogeneous spatial distribution factors of surface temperature in Tehran are different. These factors are deliberately due to different land use and vegetation in the region. In the northern regions of Tehran, an uncompromising urban structure along with green space has caused these areas to have a low surface temperature, while it is high in the major proportion of the central part of the city with high building density and poor green space. Finally, the results of the relationship between surface temperature and population distribution in different regions of Tehran show that the regions with high temperatures in districts of 4, 5, 15, 2 and 14 have a high population density.