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109 Reservoirs

Part 9. Ecological and Hydrological Interactions

  1. G Richard Marzolf1,
  2. Dale M Robertson2

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa115

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Marzolf, G. R. and Robertson, D. M. 2006. Reservoirs. Encyclopedia of Hydrological Sciences. 9:109.

Author Information

  1. 1

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

  2. 2

    United States Geological Survey, Water Science Center, Middleton, WI, US

Publication History

  1. Published Online: 15 APR 2006


Reservoirs are surface water impoundments that result from the construction of dams on streams and rivers. Limnological principles are applicable to understanding reservoir functions and the processes that control them because they exhibit lake-like characters (see Lake Ecosystems – Lake Ecosystems (Stratification and Seasonal Mixing Processes, Pelagic and Benthic Coupling). The basic water qualities of reservoirs are dependent, however, on the river that was impounded in their formation. The river's inflow dominates the upstream reaches of reservoirs. Lacustrine processes become more controlling as advective forces diminish and wind-mixing and solar heating become influential forcing factors and as the cross section of the basin widens and deepens downstream. This transition from riverine to lacustrine imposes longitudinal gradients in reservoirs that emerge as their central feature. Designs of dams and their operating schedules have considerable influence on these in-reservoir patterns and on the effects of the dam in the downstream river downstream. Various models have been developed to describe the physical, chemical, and biological processes in reservoirs. Additional studies will lead to further information to improve the models, which in turn will lead to a better understanding and management of reservoirs.


  • eutrophication;
  • impoundment;
  • models;
  • reservoir;
  • river;
  • sediment