Water year
Encyclopedia
A water year is term commonly used in hydrology
to describe a time period of 12 months. It is defined as the period between October 1st of one year and September 30th of the next.
The water year is designated by the calendar year in which it ends. (the year within which 9 of the 12 months fall).
Thus the 2010 water year started on October 1, 2009 and ended on September 30, 2010.
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.
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
to describe a time period of 12 months. It is defined as the period between October 1st of one year and September 30th of the next.
The water year is designated by the calendar year in which it ends. (the year within which 9 of the 12 months fall).
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 US national water supply data publishing system that was started in 1913. This time interval is often used by hydrologists because hydrological systems in the northern hemisphere are typically at their lowest levels near October 1.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.
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 modelingHydrological modellingHydrologic models are simplified, conceptual representations of a part of the hydrologic cycle. They are primarily used for hydrologic prediction and for understanding hydrologic processes. Two major types of hydrologic models can be distinguished:...
purposes. - Used in reports by the United States Geological SurveyUnited States Geological SurveyThe United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
(USGS) as a term that deals with surface-water supply. - 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.