Urbanization and Land surface temperature changes over Hyderabad, a semi-arid mega city in India

Abstract

Developing/developed cities have resulted in massive anthropogenic modifications of the environment through replacement of natural land cover with concrete, bricks, asphalt and metal. This reduces evapotranspiration, increases the heat storage and alters air movement. Consequently, many urban areas experience temperatures higher than their surrounding rural areas, turning them into Urban Heat Islands (UHI). Hyderabad, a Tier-1 Indian city has experienced significant land use land cover (LULC) changes during the last two decades (2001–2020) owing to rapid urbanization. This study investigates the urban growth and consequent changes in surface UHI (SUHI) intensity over this period using Landsat LULC, and Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) and Normalized difference vegetation index (NDVI). Substantial LULC changes were observed during this period with the urban area increasing by 108.8%, but barren and grasslands decreasing by 27.2% and 27.0%, respectively. Vegetation showed a decreasing trend by 19.0% from 2001 to 2015, but an increase by 24.8% during the 2015 to 2020 period. Comparison with surrounding rural areas led to the conclusion that Hyderabad urban behaved as an surface Urban Cool Island (SUCI) during the daytime and as SUHI during the nighttime with higher LST regions concentrated within 0–15 km from the city center. The area from 20 to 25 km from the city center experienced the highest urban expansion in the last two decades.