Modelling the Relationship between Urban Growth Modes and the Thermal Environment - A Case Study of the Barasat Municipality, West Bengal

Abstract

The transformation of the rural landscape through industrialisation, urbanisation and rural-urban migration contributes to the physical growth of cities using ‘built-up’ development, known as urban sprawl. Urban sprawls are often associated with the increase of Land Surface Temperature (LST) in both magnitude and spatial extent which modifies the urban thermal environment, attributable to a phenomenon known as the Urban Heat Island (UHI). Not all the urban growth is sprawl, and not all urban growth is necessarily detrimental to the environment. Measuring urban growth instead of sprawl, allows us to quantify the amount of land that has been converted to urban land use. In this project, three major types of urban growth, i.e. infilling, edge expansion, and leapfrog development have been identified and quantified from the built-up dynamics. Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS) images were used to estimate LST, and to extract the built-up area for this study. To understand the impact of these urban growth modes on the thermal environment, two methodologies have been adapted: i) GIS-based sectoral-buffer analysis, and, ii) Partial Least Square Regression (PLSR). They analyse and quantify the relative importance of urban growth modes in controlling the changing pattern of LST. The methods have been applied in the Barasat municipality, West Bengal, India. The study reveals that different types of urban expansions have different effects on the thermal environment. Edge expansion is the most important factor in determining LST change. This study may provide information contributing to a better understanding of urban development. Lowering the heat island effect may be possible through well-managed urban growth.