Analysis of spatial- temporal variation of urban thermal islands and landuse based on an environmental approach in Shiraz

Today, increase in the land surface temperature and the formation of heat islands in the metropolis areas has become one of the environmental problems. The aim of this research is spatial- temporal analysis of urban heat- island, vegetation, landuse and to identify the critical environmental zones of Shiraz urban thermal islands. For that purpose, the first 8 images were downloaded from landsat satellite including sensors of TM (Landsat 5), ETM+(Landsat 7) and TIRS/OLI (Landsat 8) for the warm period of the year during 1986 - 2015. Then, the required pre-processing schemes, land surface temperature (LST) and normalized difference vegetation index (NDVI) and landuse patterns for monitoring of the landuse changes in Shiraz were calculated. Then, the environmental criticality index (ECI) was used to identify and analysis of the sensitive regions. The results illustrated that barren lands surrounding the city in continuous and dense have the largest urban thermal islands and forming very hot temperature limits. These thermal centers in urban settlements correspond to the boundaries of the urban decay and dense context areas. At the same time, analyzing the land surface temperature maps in Shiraz indicate the coordination between the lowest class of temperature and vegetation landuse. The landuse maps also show the reduction of barren lands, vegetation and increasing the urban landuse. Thus, about 10.1 km2 of barren lands and 19.7 km2 of vegetation have been converted to urban landuse. This indicates that the decrease in vegetation cover(%36) was the most important factor in development of the heat islands in Shiraz. The highest environmental sensitivity (Crtical region, 29.7 Km2, 14.2% of studied region) is observed around the city due to existence of barren lands and in to the city around the industrial centers, around the international airport, passenger terminal(Karandish), around the metro stations, the highways and streets of heavily congested areas and urban decay context areas. Hence, the development of green roof vegetation and tailored to the indigenous climate is proposed as solution to mitigate urban thermal island and dealing with environmental crisis.

Keywords:

جزیرة حرارتی شهری , دمای سطح زمین (LST) , شاخص تفاضل به‌هنجارشده پوشش‌گیاهی (NDVI) , کاربری اراضی , حساسیت محیطی , شیراز