Document Type : Research Paper

Authors

• Elham Ghasemi ¹
• Zahra Nazemi ²
• Safoura Mokhtarzadeh ³
• Mahdi Suleimany ⁴

¹ PhD in urbanism and Researcher, Academic Center for Education, Culture and Research, Isfahan, Iran

² Master of Urban Design, Department of Urbanism, Faculty of Architecture and Urbanism. Art University of Isfahan, Isfahan, Iran

³ Ph.D. in urbanism, Department of Urbanism, Faculty of Architecture and Urbanism. Art University of Isfahan, Isfahan, Iran

⁴ Master Student of Urban Planning and Management, University of Tehran; Tehran, Iran.

Abstract

Urban heat island (UHI) is one of the most critical problems of cities in the new century, which has been created as a result of urbanization and industrialization. This study aims to investigate the relationship between the various urbanization and natural factors and UHI intensity in the city of Isfahan, Iran through correlation analysis. Five scenarios were designed, changes of land surface temperature (LST) in four seasons and one scenario to study the "LST differences when the Zayandehrood river is flowing,” The variables that have been assessed in each scenario are “green structures”, “water bodies”, “density of the built environment”, and “air pollution”. The data were analyzed based on the Pearson correlation coefficient. To generate LST maps for day and night, MODIS Aqua & Terra data from 2011 to 2021 were utilized. The green structure and water bodies maps were derived based on normalized difference vegetation index (NDVI) and normalized difference water index (NDWI), using Landsat 8 satellite images processed in Envi-met 5.3. The air pollution map was prepared based on Air Quality Index (AQI) in 2020. The results show that during the night in Isfahan, in all scenarios, heat islands, and during the day, cold islands appear. The main aggravating factor of heat islands in Isfahan is the density of the built environment; Air pollution also has little effect on increasing the LST during the day. Considering Isfahan's climate, it was found that vegetation cover has a more considerable mitigating impact on UHIs than other natural factors, even water bodies.

Keywords

• Urban Heat Island
• Pearson Correlation Coefficient
• Green Space
• Blue Space
• Building Compactness
• Air Pollution
• Isfahan Metropolis

Main Subjects

• Urban Ecology