BEIJING, May 6 (Xinhua) -- Chinese researchers used satellite remote sensing data to record 40 years of human settlement changes in China, providing data support for urban planning and management.

Impervious surfaces are the most significant feature of human settlements and mainly include artificial structures that eliminate water infiltration, such as roads covered with asphalt and concrete, parking lots and buildings.

Timely, accurate and frequent information on impervious surfaces is critical in both social-economic and natural environment applications. However, annual maps of impervious areas in China with high spatial details are lacking.

Researchers from the Department of Earth System Science at Tsinghua University and the Department of Geology and Atmospheric Sciences at Iowa State University completed the mapping of China's human settlements in 1978, and from 1985 to 2017, the researchers annually tracked changes based on remotely sensed images of impervious surfaces from a series of Landsat satellites.

Rapid automatic mapping of human settlements was realized in the cloud computing platform of the Google Earth Engine. After temporal consistency testing, information on 40 years of China's settlements was finally obtained, which filled the gap of dynamic monitoring of human settlements with high spatial resolution and temporal frequency.

According to the results of this study, impervious surface areas in China have grown rapidly in the past 40 years. In 2017, China's urban settlement area was about 146,000 square kilometers. The top five provinces in terms of urban expansion area were Shandong, Jiangsu, Guangdong, Hebei and Henan.

Since the reform and opening up in 1978, China has experienced rapid economic development and urbanization, and its land cover types have also changed dramatically.

Gong Peng, the leading researcher, said as urbanization has brought many problems and challenges, data from long-term monitoring of China's human settlements is very important in studies of socio-economic development and protection of the natural environment.

"Studies on regional urban planning and management, air and water pollution, climate change and biodiversity also require human settlement data with higher spatial resolution and temporal frequency," Gong said.

Gong said that with the acceleration of urbanization it is expected that the expansion trend of China's human settlement areas will continue until 2030.

"As continuous monitoring is crucial, we hope the mapping can provide data support for urban planning and management and can be applied to climate change, environmental protection, energy conservation and other related fields," Gong said.

In addition, the method used in this research lays a good foundation for future global-scale human settlement mapping.

The research was published in the journal Science Bulletin, and the mapping data can be downloaded at no cost.