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2 The Hydrologic Cycles and Global Circulation

Part 1. Theory, Organization and Scale

  1. Taikan Oki

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa001

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Oki, T. 2006. The Hydrologic Cycles and Global Circulation. Encyclopedia of Hydrological Sciences. 1:2.

Author Information

  1. University of Tokyo, International Center for Urban Safety Engineering, Institute of Industrial Science, Tokyo, Japan

Publication History

  1. Published Online: 15 APR 2006


The role of hydrological cycles in earth system, the amount of water on the Earth's surface and its distribution in various reserves are first introduced together with the water cycles on the Earth. The concept of mean residence time, water stored in various parts over the Earth surface as various phases, such as glacier, soil moisture, water vapor, and water flux among these reserves, such as precipitation, evaporation, transpiration, and runoff, are briefly explained with their role in global climate system, and their quantitative estimates are presented. Detailed annual water balances over land estimated by land surface models are introduced, as well. Water balance requirements over land, atmosphere, and their coupled system are explained with some application of the concept, and the role of rivers in the global hydrological cycle is quantitatively shown. Finally, the impact of increasing magnitude of anthropogenic activities on global water system and its relationships with global changes are briefly discussed.


  • global energy and water cycles;
  • mean residence time;
  • atmospheric water balance;
  • freshwater transport;
  • land surface model;
  • global change;
  • anthropogenic impact;
  • virtual water trade