Standardized Precipitation Index (SPI) – A precipitation index based on the probability of precipitation for any time duration. The SPI was specifically designed to quantify the precipitation deficit for multiple periods of time reflecting the impact of drought on the availability of different water resources. Soil moisture conditions respond to precipitation anomalies on a relatively short scale, while groundwater, stream flow and reservoir storage levels reflect the longer-term precipitation anomalies. For this reason, the SPI is calculated on both a short-term and long- term (up to four years) basis. Positive SPI values indicate greater than median (middle-most) precipitation, while negative values indicate less than median precipitation. Because the index is normalized, wetter and drier climates can be determined in the same way. A drought event occurs any time the SPI is continuously negative and reaches an intensity where the SPI is -1.0 or less. SPI indexes range as follows: 2.0 or greater – extremely wet 1.5 to 1.99 – very wet 1.0 to 1.49 – moderately wet -0.99 to 0.99 – near normal -1.0 to -1.49 – moderately dry -1.5 to -1.99 – severely dry -2.0 or less – extremely dry Also see Drought Indexes (Indices).
Source: http://www.bvsde.paho.org/bvsacg/i/fulltext/dicciona/dicciona.pdf
Web site to visit: http://www.state.nv.us/cnr/ndwp/home.htm
Author of the Water Words Dictionary source of text: Gary A. Horton
If you are the author of the text above and you not agree to share your knowledge for teaching, research, scholarship (for fair use as indicated in the United States copyrigh low) please send us an e-mail and we will remove your text quickly. Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, unlicensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test. (source: http://en.wikipedia.org/wiki/Fair_use)
The information of medicine and health contained in the site are of a general nature and purpose which is purely informative and for this reason may not replace in any case, the council of a doctor or a qualified entity legally to the profession.
The following texts are the property of their respective authors and we thank them for giving us the opportunity to share for free to students, teachers and users of the Web their texts will used only for illustrative educational and scientific purposes only.
All the information in our site are given for nonprofit educational purposes
The information of medicine and health contained in the site are of a general nature and purpose which is purely informative and for this reason may not replace in any case, the council of a doctor or a qualified entity legally to the profession.
www.riassuntini.com