Analytical study on the relationship among land surface temperature, land use/land cover and spectral indices using geospatial techniques

Monitoring changes in Land Use/Land Cover (LULC), spectral indices, and Land Surface Temperature (LST) can help to identify the areas at risk for indefensible land use, a low-grade environment, and especially urban heat islands (UHI). This study aims to examine the changing pattern of LULC, the dynamics of geospatial indices (Normalised Difference Vegetation Index (NDVI), Normalised Difference Built-up Index (NDBI), Normalised Difference Water Index (NDWI), Normalised Difference Bareness Index (NDBaI), and Normalised Difference Latent-heat Index (NDLI)), and LST patterns with the relationship among them between 1991 and 2021 in the Varanasi City Development Region (VCDR). The LULC classification was done into seven classes (using the maximum likelihood method), the LST has been retrieved, and the above spectral indices have been calculated using Landsat 5 and 8 data. Pearson’s correlation method was used to analyse the relationship between LST and spectral indices. As per result, built-up area was increased by 507.8 per cent consequently, water bodies, agricultural, barren, fallow land and vegetation cover were declined by 4.84, 18.68, 82.41, 26.18 and 22.16 per cent respectively during 1991–2021. The maximum, minimum, and mean LST increased by 6.18, 2.28, and 2.24 °C, respectively, throughout the period. A positive relationship has been observed among NDBI, NDBaI, NDLI, and LST, whereas NDVI, NDWI, and LST have an inverse relationship. The finding explains the high number of water bodies, healthy vegetation cover, sufficient open space, and less concrete surface are necessary to maintain the LST and its related problems. So, an SPURS plan has been proposed to maintain the thermal environment of VCDR. This study can be a useful guide for planners and policymakers by providing a scientific background as well as the suggestions for sustainable urban management and development in VCDR and other cities as well.