Impacts of Urban Expansion on Urban Heat Island - A Geospatial Approach

Abstract

Growing urbanisation has led to increase in the built up area, reduction in open and green spaces with in the cities and the periphery. The urban saturation and the enlargement of the built space have determined environmental changes, increasing the already precarious condition of the natural systems in these spaces of high saturation. It results in to the formation of Urban Heat Island (UHI). Over the last few years, Ahmedabad has experienced rapid urbanization and associated Urban Heat Island (UHI) effects. This study aims at analysing spatially and temporally, the impact of urban form expansion on UHI in Ahmedabad using Landsat thermal images. The Mono Window Algorithm has been used to retrieve Land Surface Temperature (LST) from the thermal bands of LANDSAT-5, 8 TM satellite data. Various spatial analysis techniques were used to explore the relationships between area, compactness ratio, the gravity centers of urban land, and UHI. Under the similar urban land area condition, UHI and compactness ratio of urban land were in positive correlation. The moving direction of the UHI gravity center was basically in agreement with urban land sprawl. The encroachment of urban land on suburban land is the leading source of UHI effect. The results suggest that urban design based on urban form would be effective for regulating the thermal environment.