Water year
A "water year" is term commonly used in Hydrology to describe a time period of 12 months.
Definition
It is defined as the period between October 1st of one year and September 30th of the next. [1] The water year is designated by the calendar year in which it ends. (the year within which 9 of the 12 months fall). [2] Thus the 2010 water year started on October 1, 2009 and ended on September 30, 2010.
Origin
Use of water year as a standard follows the national water supply data publishing system that was started in 1913.[3] This time interval is often used by hydrologists because hydrological systems are typically at their lowest levels near October 1.[4] The increased temperatures and generally drier weather patterns of summer give way to cooler temperatures, which decreases evaporation rates. Rain and snow replenish surface water supplies.[5]
Uses
Examples of how water year is used:
- Used to compare precipitation from one water year to another.
- Used to define a period of examination for hydrologic modeling purposes.
- Used in reports by the United States Geological Survey (USGS) as a term that deals with surface-water supply. [6]
- The end of the water year is used by the CoCoRaHS project as an opportunity for observers to audit and verify data for their site.
References
- ^ United States Geological Survey, "Explanations for the National Water Conditions", http://water.usgs.gov/nwc/explain_data.html, Retrieved 16 October 2011.
- ^ United States Geological Survey, "Explanations for the National Water Conditions", http://water.usgs.gov/nwc/explain_data.html, Retrieved 16 October 2011.
- ^ Minnesota Department of Natural Resources, "Water Year Data Summary", http://files.dnr.state.mn.us/publications/waters/wysumm97_98.pdf
- ^ Minnesota Climatology Working Group, "Water Year Precipitation Maps", http://climate.umn.edu/doc/hydro_yr_pre_maps.htm, Retrieved 10 October 2011.
- ^ CoCoRaHS project, "Water Year Summary Reports", http://www.cocorahs.org/wateryearsummary/, Retrieved 10 October 2011.
- ^ United States Geological Survey, "Explanations for the National Water Conditions", http://water.usgs.gov/nwc/explain_data.html, Retrieved 16 October 2011.
External links
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