Geospatial evaluation of normalized difference vegetation index (NDVI) and urban heat island: a spatio-temporal study of Gandhinagar City, Gujarat, India

Abstract

The latest Conference of the Parties (COP) demonstrated that development and 'Climate change’ are inextricably intertwined, making them the primary fields to be tackled in addressing rational global tendencies. Since the beginning of urbanization, asphalt, and concrete have supplanted natural vegetation, which has led to an increase in energy demand. This increase has accelerated the urban heat island (UHI) effect and paved the way for a rise in building energy consumption. In addition to that, the increased impervious surfaces capture more solar radiation, increasing Land Surface Temperature (LST). Increasing Greenspace, where vegetation changes have been monitored with the help of the Normalised Difference Vegetation Index (NDVI) since the early 1980s, has been suggested as a strategy for urban areas in response to increasing urbanization and forecasts of more frequent heatwaves under a climate change scenario. The present study focuses on using remotely sensed data of MODIS to evaluate the relationship between, Urban Greenspace and UHI for the city of Gandhinagar, Gujarat. For the detection of relation as well as change, Land Surface Temperature (oC) and Precipitation rate (mm/day) were incorporated. This study compared UHI and NDVI for an annual average for the years 2003 and 2018. In the entire study period, a considerable change in land use was observed with a significant increase in build-up area. Correlation among the variables depicted a significant negative relation between NDVI (r = −0.76) and LST and Precipitation (r= −0.38). The linear trend showed a significant drop in precipitation in recent years. For a better understanding of continuous time series data, cross-wavelet transformation was used. The result of the wavelet transformation revealed a substantial coherence period and phase relationship between the variables. The finding of the study states that rapid urbanization is the chief contributor to the changes in the Land Surface Temperature.