A quantitative analysis of urban growth and associated thermal characteristics using Landsat satellite data

Abstract

Urbanization transforms the natural landscape to anthropogenic urban land use and changes surface physical characteristics. Accurate information on the extent of urban growth and its impacts on environment are of great interest for diverse purposes. As a result, increased research interest is being directed to the mapping and monitoring of urban land use using remote sensing techniques. However, there are many challenges in deriving urban extent and development densities quantitatively. This study utilized remote sensing data of Landsat TM/ETM+ to assess urban sprawl and its thermal characteristics in Changsha of central China. A new approach was proposed for quantitatively determining urban land use extents and development densities. Firstly, impervious surface areas were mapped by integrating spectral index derived from remotely sensed data. Then, the urban land extents and development densities were identified by using moving window calculation and selecting certain threshold values. The urban surface thermal patterns were investigated using Landsat thermal band. Analysis results suggest that urban extent and development density and surface thermal characteristics and patterns can be identified through qualitatively based remotely sensed index and land surface temperature. Results show the built-up area and urban development densities have increased significantly in Changsha city since 1990s. The differences of urban development densities correspond to thermal effects where higher percent imperviousness is usually associated with higher surface temperature. Remotely sensed index and land surface temperature are demonstrated to be very useful sources in quantifying urban land use extent, development intensity, and urban thermal patterns.