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173 Global Water Cycle (Fundamental, Theory, Mechanisms)

Part 15. Global Hydrology

  1. Thomas C Pagano1,
  2. Soroosh Sorooshian2

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa179

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Pagano, T. C. and Sorooshian, S. 2006. Global Water Cycle (Fundamental, Theory, Mechanisms). Encyclopedia of Hydrological Sciences. 15:173.

Author Information

  1. 1

    Natural Resources Conservation Service, Department of Agriculture, Portland, OR, US

  2. 2

    University of California, Department of Civil and Environment Engineering, Irvine, CA, US

Publication History

  1. Published Online: 15 APR 2006


Water cycle is the never-ending movement of water on Earth. Water continuously cycles through various reservoirs in the ocean, sky, and soil. A variety of measurement systems are necessary to quantify the fluxes between reservoirs, ranging from simple buckets to measure rainfall to sophisticated satellites orbiting the Earth. The hydrologic cycle is mainly characterized by its variability in space and time. The Earth contains an incredible diversity in climates, including rainforests, parched deserts and frozen tundra. Water cycle at any given location changes both rapidly and slowly, with the passing of flash floods to the decadal shifts in ocean patterns. Anticipated impacts of human-induced climate change on the hydrologic cycle are as yet unknown, but the consequences are potentially severe. Nonetheless, humans have a long history of altering the hydrologic cycle including the diversion and impoundment of streamflow, pumping of groundwater, irrigation of fields and management of forests. While the water cycle has been recognized for ages, many interesting fundamental research questions remain.


  • water cycle;
  • precipitation;
  • evaporation;
  • streamflow;
  • hydrologic data;
  • simulation models;
  • climate change and land use