Still waters (including standing water , standing water or standing water ) are natural or artificially created bodies of water in which there is no or only a slight flow velocity . They belong to the inland waters , they face the flowing waters . The oceans and seas do not belong to the still waters .
Within the hydrology , the busy Limnology with standing and running waters, primarily freshwater and special forms, but saline inland waters (such as salt water lakes), other than those of Oceanography fall.
Important criteria for differentiating from still waters are their size, depth, water flow and the method of formation. In terms of depth, a distinction is made between:
- Lakes that are deep enough to allow temperature stratification to develop that persists for a long time and can only be redeployed a few times per year. This is usually the case from a depth of around 8 to 10 m. Plant growth is only possible in the bank area ( littoral ).
Shallow waters , the water bodies of which are frequently redeployed, sometimes even daily. The shallow depth means that floating plants can reach the bottom with their roots and theoretically colonize the entire water surface. When differentiating between different shallow waters, the criteria of the water flow and the method of formation are important:
- Ponds are shallow lakes with or without permanent water flow. They cannot be drained without structural measures or the use of pumps. Very large ponds are also called shallow lakes , while those with a small water surfaceare
- Ponds are shallow, periodically drying water accumulations with naturally strongly fluctuating water levels without water flow or drainage. They can be of natural or human origin.
- Pools, sheets or puddles are episodically water-bearing.
- Ponds are man-made bodies of water, the water level of which can usually be artificially regulated, so that a pond can also be temporarily drained.
- Solle are glacially dependently arisen ponds or pools of former dead ice , in northeast Germany also Pfuhle called.
- Oxbows and oxbow lakes are constricted meanders , with the oxbow lake no longer being connected to the river.
Still waters can also be distinguished based on their size. Common categories are:
- Small bodies of water such as puddles, pools etc. are only up to a few square meters in size.
- Small bodies of water (ponds, ponds, small ponds) have a surface that is up to about 1 hectare in size.
- Large bodies of water , including lakes and large ponds, are larger than about 1 hectare.
The limit values are only a useful guide for practical use.
Forms of still waters are also artificially created ponds, ponds or lakes that have special uses such as fish farming, mining or bathing purposes. Flooded gravel pits , clay pits and open-cast mining holes are also included. They all show changed living conditions and corresponding biocenosis .
Not fresh water filled pond are salt lakes and - lacquers or those with completely altered chemistry as acid lakes of all kinds in the border area of limnology with the Oceanology lying coastal (littoral) waters, such as the. Lagoons , often also a different salinity have as the adjoining open sea. Spring pots , cave lakes and other special underground forms lie in the intersection with groundwater sciences . In the border area to wetland research there are phenomena such as Blänken , Väte and Alvar lakes , pools and paintwork networks, or flood zones . Standing water on glaciers and thawing permafrost is also investigating glaciology as a water science . Hot lakes and shallow waters represent a special branch in contact with volcanology , including many over-acidic still waters.
In the European Union (EU) according to Directive 2000/60 / EC (EU Water Framework Directive, WFD), the ecological status of rivers and surface waters (such as groundwater ) is analyzed according to various criteria and classified according to five grades: “very good “,“ Good ”,“ moderate ”,“ unsatisfactory ”,“ bad ”.
- Dieter Glandt: Practical small water science . Laurenti Verlag, Bielefeld 2006, ISBN 3-933066-28-X .
- Environmental goals - the good condition for our waters, bmnt.gv.at. Retrieved April 4, 2018 .
- Sibylle Wilke: Ecological condition of flowing waters . In: Federal Environment Agency . October 18, 2013 ( Umweltbundesamt.de [accessed April 4, 2018]).