Perennial stream
A perennial stream or perennial river is a stream or river (channel) which always flows in some parts all year round during years of normal rainfall.[1] Perennial streams are different to intermittent streams; which normally stop flowing for weeks or months each year. They are also different to ephemeral streams that flow only for hours or days after rainfall. During unusually dry years a perennial stream may stop flowing. In a drought, they may not flow for months. The differences between perennial, intermittent, and ephemeral streams are not exact and can change if different measures are used by different groups.
In dry weather it may not be possible to see the water flowing, or see any water at all. In streams with gravel, sandy or rock bottoms, the water may be flowing beneath or between the rocks. In biology, a stream is flowing if there is enough water to support aquatic life, including fish and gill-breathing amphibians, benthic insects, crustaceans, and mollusks. These can live in a shallow flow beneath rocks or logs. The flow may be so small that it can not be measured by stream flow measurement instruments.[2]
Perennial Stream Media
Frozen stream in Enäjärvi, Pori, Finland
Stream near Montriond in south-eastern France
Aubach (Wiehl) in North Rhine-Westphalia, Germany
Creek babbling through Benvoulin, Canada, wetlands
Wyming Brook in Sheffield, UK
A small stream in Lake Parramatta, Sydney
Stream with low gradient surrounded by natural riparian vegetation (Rhineland-Palatinate)
A low level stream in Macon County, Illinois
Small tributary stream, Diamond Ridge, Alaska
References
- ↑ Meinzer, Oscar E. (1923). Outline of ground-water hydrology, with definitions. Washington, DC: US Geological Survey (USGS). p. 57. Water Supply Paper 494.
- ↑ "Definition of "Perennial Stream"". Office of Surface Mining - US Department of the Interior. Archived from the original on October 7, 2006. Retrieved March 28, 2007.