Analysis of Urban Heat Island Effect in Rajkot City Using Geospatial Techniques

Abstract

Rapid urbanization and unsustainable industrialization have shown negative impact on climate, which has led to climate change and ultimately leading towards global warming. It is estimated that presently global warming is increasing at the rate of 0.2 °C per decade, eventually making urban areas warmer. Haphazard development in the Indian cities have made them prone to urban heat island (UHI) phenomenon. Higher temperature in core urban areas due to concretization and excessive energy usage in comparison to its rural surroundings is known as the UHI effect. Higher UHI intensity in certain urban core areas put the population at a great risk of morbidity, and mortality makes the UHI assessment prerequisite during current times. This study has assessed the spatiotemporal effect of UHI in Rajkot city using LANDSAT5TMand LANDSAT 8 OLI remote sensing data. The study distinguished the Land use/ Land cover (LULC) using Landsat images for the year 2009 and 2017 in order to perform maximum livelihood classification. Utilizing classified results and Normalized Difference Vegetation Index (NDVI), land surface temperature (LST) was derived using mono-window algorithm. Subsequently, ambient air temperature was scrutinized and isotherm was derived for three locations in Rajkot city such as Madhapar chowk, Trikon Baugh and Atika industrial area of different typology. Later on, discrepancy between LST and Ambient air temperature was figured out. Some environmental factors such as the concentrations of carbon dioxide and carbon monoxide, which contribute in UHI effect, were also analysed for the above-mentioned locations. On the basis of various results derived and analysis of temperature trend of past 60 years, it was determined that UHI effect was more prominent in the central business district (CBD) area of the selected regions. The results also revealed that the study region has experienced an increase of 0.3 °C in ambient air temperature in past 60 years. The built-up area and LST for LULC classes have also increased by 8.42% between 2009 and 2017 in Rajkot. The reasons behind increment in temperature can be: Rajkot, being the largest city of Saurashtra region has experienced rapid urbanization, higher energy consumption, rural to urban migration, which has modified the LU/LC of the city and eventually resulted into haphazard development that subsequently increase land surface temperature (LST).