Spatio-temporal evolution of urban morphology in the Yangtze River Middle Reaches Megalopolis, China

Abstract

The Yangtze River Middle Reaches Megalopolis (YRMRM) is the primary urban cluster in central China, which is of vital ecological and economic importance over the Yangtze River basin. To fill the gap on updated evidence needed to support sustainable spatial planning and development in the YRMRM, we systematically characterise its urban spatial patterns and analyse their changes from 2000 to 2015 from two levels. At the regional level, landscape indices are used to depict urban morphology from four aspects, including fragmentation, complexity, contiguity and dispersion. At the local level, spatial autocorrelation analysis is conducted to detect whether the urban morphological patterns, as described by the four landscape indices, are clustered locally. The results showed an increasingly accelerated urban expansion in the YRMRM (approximately 250 km??2/a), contributed mainly by agricultural land conversion (60-80%, depending on subdivisions). An uneven spatial development pattern is identified in the three key metropolitan areas in the YRMRM. The Wuhan Metropolitan Area develops in a continuous and less fragmented fashion, with increased shape complexity and local dispersion. The spatial pattern of the Changsha-Zhuzhou-Xiangtan Metropolitan Area seems to be increasingly fragmented, complex and dispersed. The spatial development pattern in the Poyang Lake Metropolitan Area is overall continuous with an increasingly complex shape and severe local dispersion. Using landscape indices as indicators of sustainability, we discuss the potential environmental and climatic challenges in the YRMRM and the three metropolitan areas. Our results could help to raise awareness and concern for well-targeted management and planning in specific areas.