Acta Geographica Sinica ›› 2023, Vol. 78 ›› Issue (7): 1641-1658.doi: 10.11821/dlxb202307006

• Academician Forum • Previous Articles     Next Articles

Green water in China: Geological structure and its significance

WANG Guangqian1,2,3(), ZHANG Yu1,2,3, XIE Di1,2,3, ZHONG Deyu1,2,3,4()   

  1. 1. State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China
    2. Key Laboratory of Hydrosphere Sciences of the Ministry of Water Resources, Tsinghua University, Beijing 100084, China
    3. Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
    4. State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China
  • Received:2023-03-06 Revised:2023-07-02 Online:2023-07-25 Published:2023-08-01
  • Contact: ZHONG Deyu E-mail:dhhwgq@tsinghua.edu.cn;zhongdy@tsinghua.edu.cn
  • Supported by:
    National Natural Science Foundation of China(52209026);The Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0208)

Abstract:

Terrestrial recycling of green water, which is created through a continuous cycle of evapotranspiration, atmospheric transport, and terrestrial precipitation, serves as bridges connecting hydrosphere, atmosphere, biosphere, and anthroposphere. Limited knowledge of terrestrial recycling may underestimate the impact of human activities on water and ecology. This study focuses on the structure of China's green water recycling (CGWR) and quantifies the contributions of natural and human ecosystems. Results indicate a high green water recycling ratio (50.4%) and a large recycled amount (2.75 trillion m3/a) over China, with significant south-to-north transport structures over eastern China, southwest-to-northeast transport structures from southwestern China to northern China, and high self-recycling structures in western China. The grassland-dominated Qinghai-Tibet Plateau provides the largest amount of green water (about 800 billion m3/a) and serves as the most critical region for CGWR. The forest-dominated southern hilly region and Yunnan-Guizhou-Sichuan region play a crucial role in supplying green water to a wide area of China. The cropland-dominated Middle-Lower Yangtze Plain and the grassland-dominated Loess Plateau are the key hubs for south-to-north and southwest-to-northeast transport of green water. The structure of CGWR is driven by large-scale geosystems such as ecosystems and atmospheric circulation systems, and has strategic implications in the following three aspects. First, CGWR serves as the "domestic cycle" of water, based on which a general domestic-level water governance framework can be established. Second, CGWR is a representative picture of the water-related processes in the Mountain-River-Forest-Farmland-Lake-Grassland-Desert (MRFFLGD) system and serves as a critical pivot to actualize the conservation and improvement of the MRFFLGD system. Finally, CGWR, together with inter-basin water resources transfer and virtual water transfer, forms a complete picture of China's inter-basin water transfer. The scientific coordination and integration of the three processes present a new approach for achieving spatial equilibrium between China's water resources and economic development.

Key words: green water, water cycle, China, Mountain-River-Forest-Farmland-Lake-Grass-Desert system, systematic governance