2.2.2. Global artificial impervious areas
Artificial impervious areas are
predominant indicators of human settlements. Timely, accurate and
frequent information on the artificial impervious areas is critical for
understanding the urbanization process and the land use/cover change, as
well as their impacts on the environment and the biodiversity. Based on
the full archive of the 30-m resolution Landsat images on the Google
Earth Engine platform, the annual
global artificial impervious areas
(GAIA) are mapped from 1985 to 2018 (Gong, Li et al. 2020). With the
ancillary datasets, including the nighttime light data and the
Sentinel-1 Synthetic Aperture Radar data, the performance of our
previously developed algorithm is improved in arid areas. The GAIA
dataset can be freely downloaded from http://data.ess.tsinghua.edu.cn.
The GAIA data with a spatial resolution of 30 m from 2000 to 2018 are
used in this study to investigate the urbanization development over the
LP during this period (He, Yang et al. 2020). According to the GAIA data
in 2018 and 2000, there are six
UAs over the LP, including Xi’an,
Taiyuan, Luoyang, Hohhot, Yinchuan and Xining-Lanzhou (Fig. 1). The
artificial impervious area in Xi’an, Taiyuan, Luoyang and Hohhot reached
1400
km2,1700
km2, 1000 km2 and 1000
km2 in 2018, which is 2 times, 2 times,1.5 times and
1.5 timesthat in 2000, respectively (Fig. 2). Due to the relatively slow
economic development, the artificial impervious area in Yinchuan, Xining
and Lanzhou only increased by 100–200 km2 in 2018
compared to 2000.