Transformation of Urban Surfaces and Heat Islands in Nanjing during 1984-2018

One of the many consequences of urbanization is the expansion of cities into rural areas, which leads to the transformation of lands from natural surfaces to developed surfaces. It is widely considered an established fact that urbanization generally increases the heat island effect. The objective of this study is to understand the pattern of urban surface transformation in the city of Nanjing since 1980 and to find, if any, the correlation between such transformation and the urban heat island effect. The supervised classification technique was used to analyze the remote sensing data obtained from Landsat to identify the different kinds of underlying surfaces. Land surface temperatures were calculated using a subset of Landsat data. The correlation between the transformation of underlying surfaces and the heat island effect was established through analytical and statistical approaches. The results clearly show that the proportion of developed surfaces has been steadily rising in Nanjing in the past 30 years and that the urban heat island effect is positively correlated with the expansion of hard pavement and the deterioration of green surfaces and water bodies considering the general trend.