Analysis of land surface temperature trend and climate resilience challenges in Tehran

Abstract

Urban heat island is one of the most important consequences of climate change in cities. Various factors accelerate temperature increase in urban surfaces. Widespread use of impermeable materials with high heat capacity; albedo and trapping of incoming solar radiation in urban structure which prevents reflection; reduction in cooling at night due to increased building heights; and changes in the complex urban geometry are among these factors. The aim of this study is to investigate the surface temperature of Tehran in a 30-year period (1984–2014). The required images and land surface temperature maps were prepared using a split-window algorithm on thermal bands of landsat images for four periods. All images had been taken at 11:00–14:00 in summer. Temperature factors were calculated for different neighborhoods, and two patterns were obtained. One pattern showed the formation of urban heat island in barren lands, large workshop areas, and areas with military land use, and the other one showed the formation of urban heat island in dense building population areas with limited green space. The results indicate an increase in the area of the regions with a higher temperature in the city. In 1984, the smallest area belonged to the above 48 °C temperature category (1.8 ha), while in 2014 the below 25 °C category had the smallest area (0 ha). It was observed that the area of the former category reached over 1740 ha in 2014. Neighborhood temperature factors show that 17 Shahrivar and Khajeh Nasir–Hoghoughi neighborhoods are the hottest neighborhoods in Tehran. The findings in this study may persuade urban managers scientifically to make preparations for changing the life style focusing on urban macro-scale planning which is a widely emerging issue resulted from recent effects on Tehran’s climate resilience. Considering the importance of urban planning priorities in urban ecosystem services, it is essential to make use of all urban elements and fill the empty gap between urban ecosystem services production and their consumption in the city by wise and smart urban management.