Publications

Xu, RH; Hu, YH; Gao, H; Pan, ZR (2017). Derivation of fractional urban signals in better capturing urbanization process. ENVIRONMENTAL EARTH SCIENCES, 76(12), 412.

Abstract
Rapid urbanization has changed land use and urban structure in China and therefore greatly modified land surface properties and land-atmosphere interactions, causing further local and regional climate change. Climate model simulation and urbanization process analysis are usually limited by poor accuracy of coarse-resolution land use/cover products employed in regional climate models. This study sought to identify better urban representation from Landsat images and monitor urban expansion by change detection of spatial patterns and urban fractions in southeastern coastal region of China. We used the improved normalized indices-based method to classify urban and built-up areas from Landsat images in Jiading District, Shanghai. Classification results were evaluated at both the pixel scale and the model grid scale, with overall accuracy of 88% and k coefficient of 0.76. Moreover, urbanization process over the Guangzhou-Foshan-Dongguan area was examined from 2000 to 2009. We aggregated the original results of urban classification data from Landsat images as fractional cover information in 1-km grids. The total fractional urban change in 2000-2005 (10.65%) was approximately three times greater than in 2005-2009 (3.38%). We also compared the fractional cover of urban expansion with the corresponding period of MODIS land cover products. It showed that existing land cover products in models had deviations and could not capture well the underlying conditions and urbanization process. Different fractional covers of urban scenarios were expected to provide better inputs for accurate modeling of critical environmental feedbacks over expanding urban clusters.

DOI:
10.1007/s12665-017-6747-x

ISSN:
1866-6280