Water year

The runoff year, even hydrological year or water year comes from the field of Hydrology ( Hydrology ). Runoff years are different from the calendar years usually. This classification choose to capture the rainfall in the annual balance sheet may have already fallen in late autumn and early winter and stored as snow or ice in the catchment. These precipitates are but outflow effect until the following calendar year as meltwater. In glaciology one speaks of financial year or financial year of the glaciers.

Country-specific definitions

Germany: November 1 to October 31

In Germany, DIN 4049 defines the time period from 1 November to 31 October, the reason that the end of October the water reserves in Germany experience has shown the lowest. By shifting by two months ( with respect to the calendar year), the advantage is that the water that is deposited in the form of snow and ice flows in the following year, may be included in the hydrological financial statements.

Is called an outflow year with the calendar year in which the outflow Years Months January happen until October. Thus, the runoff year begins 2008 on November 1, 2007 and ends on 31 October 2008. On 1 November 2008, then starts the drain 2009. The runoff year is divided into winter (November to April) and summer months (May to October).

Switzerland: 1 October to 30 September

Common in Switzerland is the period between 1 October and 30 September of the following year as a hydrological year ( definition according to the Federal Office of Energy ).

This definition takes into account the earlier onset of absorption of water by snow and ice in the high Alps.

Austria

In Austria also was the regulation October 1 to September 30 in use, but increasingly is the regulation 1 November to 31 October of the DIN 4049 standard. In the glacier research is used as the financial year, the period 1 September to 31 August.

United States

In the U.S., the United States Geological Survey, the water year is defined as the period from 1 October to 30 September of the following year. However, other definitions are also used.