A new landscape index for quantifying urban expansion using multi-temporal remotely sensed data

Landscape metrics or indices have been commonly used for quantifying landscape patterns. However, most of these indices are generally focused on simple analysis and description of the characterization of the geometric and spatial properties of categorical map patterns. These indices can hardly obtain the information about the spatio-temporal dynamic changes of landscape patterns, especially when multi-temporal remote sensing data are used. In this paper, a new landscape index, i.e., landscape expansion index (LEI), is proposed to solve such problems. In contrast with conventional landscape indices which are capable of reflecting the spatial characteristics for only one single time point, LEI and its variants can capture the information of the formation processes of a landscape pattern. This allows one to quantify the dynamic changes in two or more time points. These proposed indices have been applied to the measurement of the urban expansion of Dongguan in Guangdong province, China, for the period of 1988-2006. The analysis identifies three urban growth types, i.e., infilling, edge-expansion and outlying. A further analysis of different values of LEI in each period reveals a general temporal transition between phases of diffusion and coalescence in urban growth. This implies that the regularity in the spatiotemporal pattern of urban development in Dongguan, is consistent with the explanations according to urban development theories.