Land use/land cover change and surface urban heat island intensity: source-sink landscape-based study in Delhi, India

Urbanization-induced rapid land use/land cover change (LULCC) modifies the thermal characteristics of a region at local scale and often creates urban heat island (UHI) effects. Delhi also experiences such enhancing UHI scenario. In present study, LULCC was linked with the land surface temperature (LST), and surface urban heat island intensity (SUHII) was measured at the sub-district level. Landsat imageries and MODIS LST product for 2001, 2009 and 2017 were main data sources. LULC classification and LST were derived using maximum likelihood classification and single-channel algorithm techniques, respectively. Proposed LULC classification scheme was built-up, current fallows land, bare land (or source landscape); and crop land, vegetation and water bodies (or sink landscape). SUHII was calculated using the contribution index of both source and sink landscapes and landscape index (LI). Results from LI also supported with temperature vegetation feature space index, transformed difference vegetation index, enhanced vegetation index, diurnal temperature range, population density and transect analysis. The result showed that sub-districts of North, North-East, East and West Delhi were more prone to SUHII due to the highly dense built-up area and industrial area. SUHII was comparatively low in the sub-districts of South and South-West Delhi because of less built-up area as well the presence of greenery. Not only built-up but also fallow land and barren land contributed significantly in some places, i.e. South and South-West Delhi. Besides, urban green space and green crop field reduced the LST sufficiently in some areas, i.e. Najafgarh and New Delhi. Again, this study could help to understand UHI in Delhi at sub-district level.