Definitions of Drought
"Drought is a condition of moisture deficit sufficient to have an
adverse effect on vegetation, animals, and man over a sizeable area."
-- (Warwick, R.A., 1975, Drought hazard in the United States: A research assessment: Boulder, Colorado, University of Colorado, Institute of Behavioral Science, Monograph no. NSF/RA/E-75/004, 199 p.)
- Meteorological drought:
- "A period of abnormally dry weather sufficiently prolonged for the lack of water to cause serious hydrologic imbalance in the affected area." (Huschke, R.E., ed., 1959, Glossary of meteorology: Boston, American Meteorological Society, 638 p.)
- Agricultural drought:
- "A climatic excursion involving a shortage of precipitation sufficient to adversely affect crop production or range production." (Rosenberg, N.J., ed., 1979, Drought in the Great Plains--Research on impacts and strategies: Proceedings of the Workshop on Research in Great Plains Drought Management Strategies, University of Nebraska, Lincoln, March 26-28: Littleton, Colorado, Water Resources Publications, 225 p.)
- Hydrologic drought:
- "A period of below average water content in streams, reservoirs, Groundwater aquifers, lakes and soils." (Yevjevich Vujica, Hall, W.A., and Salas, J.D, eds., 1977, Drought research needs, in Proceedings of the Conference on Drought Research Needs, December 12-15, 1977: Colorado State University, Fort Collins, Colorado, 276 p.)
Definitions from the National Drought Mitigation Center
Because the definition of a drought can be a complex issue, a collection of other definitions of drought follows. Note that particular definitions may not be appropriate for individual circumstances, and that some of the definitions may be quite location specific. Other definitions can be suggested for inclusion by sending email to the maintainer listed at the bottom of this page; be sure to include a full bibliographic reference for the definition.
- Drought: Dryness due to lack of rain... An absolute drought is a period of at least 15 consecutive days to none of which is credited 0.01 inches of rain or more. A partial drought is a period of at least 29 consecutive days, the mean daily rainfall of which does not exceed 0.01 inches. A dry spell is a period of at least 15 consecutive days to none of which is credited 0.04 inches or more... The definitions of absolute drought anf partial drought were introduced in British Rainfall, p. 21, 1887, while that of dry spell was first used in British Rainfall, p. 15, 1919 [from Meteorological Glossary, Air Ministry, 3rd ed., London, 1944, p. 68.] [from Glossary of Geology and Related Sciences, American Geological Institute, Washington, D.C., 1957, p. 89.).