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Land Cover Atlas Sheds Light on 20-Year Environment Change of China
 Date: 2017-11-16  Page Views:

Land cover, as a geographical feature, is a synthesis of observable natural and artificial objects on the surface of the Earth. The dynamics of land cover change on the planet is a record of how mankind interacts with the Nature and their arduous efforts to improve living conditions since the primitive age of "slash and burn”.

At the country level, land cover changes over time can be regarded as indicators that shed light on its natural environment, ecosystem, economic development, and the livelihood of the people on this land.

The world's first land cover atlas “Land Cover Atlas of the People’s Republic of China (1:1,000,000)” has been published in September, 2017 in both Chinese and English. This atlas is designed according to international map sub-division standard. That atlas provides the most comprehensive look at land-surface conditions across China, and records its land cover changes in 1990, 2000, and 2010, a period witnessing rapid economic growth of China.

The land cover data (ChinaCover) used in this atlas has the following unique characteristics:

The classification system with six primary classes and 40 secondary classes was established, which conformed both to international classification criteria and the land cover features of China, and assured comparability and convertibility to other commonly used classification systems.

Chinese environmental satellite data (HJ-1A/B) was used for the land cover mapping for the year 2010, supplemented with synthetic aperture radar (SAR) data to improve recognition of water body and built-up surfaces.

A total of 111,356 ground samples were used for establishing the classification training sample dataset, creating classification criteria, controlling quality and revising misclassified pixels.

The automatic pre-processing of huge amount of remote sensing data was accomplished using a high performance computing platform. An object-oriented based classification method was employed to produce the ChinaCover2010. A change detection algorithm was used to generate the ChinaCover2000 and ChinaCover1990, thus ensuring data comparability over the three time periods.

A quality control specification (QCS) system was established for data processing, segmentation, classification and mosaicking. Validation was carried out for ChinaCover2010 using 31,658 independent ground-surveyed samples, which showed an average accuracy of 94% for the primary classes and 86% for the secondary classes.

The atlas is produced to meet a wide variety of national spatial needs for the agriculture, forestry, water conservation and environment protection. It provides access to the application of these land cover data, which can be used to study a wide range of fields such as global change, biodiversity conservation, and to assess the rates, trends, causes and consequences of contemporary China’s land cover change.

The land cover types such as forest lands, grasslands, and wetlands are important participants in the process of carbons cycle. Therefore, related data offered by the atlas also provides important reference for Chinese government to make carbon-budget policy by assessing the capacity of carbon sequestration based on the land covers, and therefore facilitate China to achieving its carbon-dioxide emission goals on the Paris Climate Change meeting.

It takes six years to complete the work from the data production in 2011 to the atlas publication in 2017. The atlas compilation, which is led by the Institute of Remote Sensing and Digital Earth (RADI) under the Chinese Academy of Sciences (CAS), involves collaborative efforts of over 240 scientists and technicians from CAS institutes, other research, education and government agencies.

This work is mainly supported by CAS Strategic Priority Research Program “Climate Change: Carbon Budget and Relevant Issues” and the Ministry of Environment Protection (MOST) / CAS joint project on “Monitoring and Assessment of National Ecosystem Changes between 2000 and 2010”.

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