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145 Groundwater as an Element in the Hydrological Cycle

Part 13. Groundwater

  1. William M Alley1,
  2. James W La Baugh2,
  3. Thomas E Reilly2

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa153

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Alley, W. M., La Baugh, J. W. and Reilly, T. E. 2006. Groundwater as an Element in the Hydrological Cycle. Encyclopedia of Hydrological Sciences. 13:145.

Author Information

  1. 1

    United States Geological Survey, Office of Ground Water, San Diego, CA, US

  2. 2

    United States Geological Survey, Office of Ground Water, Reston, VA, US

Publication History

  1. Published Online: 15 APR 2006


Groundwater commonly is portrayed in diagrams of the hydrological cycle as a single pool of water with simple transfers of water to and from the land surface, oceans, and atmosphere. In reality, groundwater is an integral part of a complex hydrological cycle that involves the continuous movement of water on Earth. We begin with a global perspective on the importance of groundwater in the hydrological cycle and then address the importance of understanding the dynamics of groundwater-flow systems. We next turn our attention to groundwater budgets and the effects of humans and climate on these budgets. The final section is devoted to a discussion of interactions between groundwater and surface water, and we highlight the importance of these interactions in the hydrological cycle.


  • groundwater;
  • hydrological cycle;
  • water budgets;
  • surface-water/groundwater interactions;
  • groundwater depletion;
  • groundwater-flow systems;
  • wetlands;
  • streams