pond
A pond is an artificially created still water , usually with an inlet and outlet. In contrast to a lake, the depth is so shallow that no stable temperature stratification develops.
Origin and special features
Ponds are considered to be a historically significant development in hydraulic engineering . It was only through the storage of drinking and industrial water that the expansion of settlement in urban and rural areas became possible. This importance of the ponds for water storage has only gradually declined in recent times with the modern water supply from the groundwater by means of deep wells and pressure pipes ( waterworks ) - this also applies to the more than 2000 before the start of the spread of steam power in the 19th century Years ago, it was used as a mill pond for the operation of water mills to drive various aggregates (grinders, hammer mills, sawmills, etc.). While some of the cities had been equipped with new water supply techniques since the middle of the 19th century (see water supply in Hamburg ), rural areas were still dependent on ponds for a long time.
Usually a flowing body of water ( brook , moat ) is dammed and a storage volume is created by creating a basin, the bottom of the pond being designed with a gradient so that the pond can be completely drained at the lowest point. There the water level is dammed and regulated by means of a drainage structure ( Mönch , harrow system in reservoirs ) so that the pond can also be drained if necessary. The drainage of a pond is carried out in the context of its use and maintenance or maintenance (e.g. fishing, cleaning or desludging). Ponds or ponds , which as a rule have no drain, are sometimes referred to colloquially as ponds, but this is incorrect.
Usually, the smaller the size and depth of a still water body, its stability and lifespan decrease rapidly because the relative proportion of peripheral structural elements increases with decreasing water volume. The smaller a standing water body, the greater the impact of the input of substances on the water body, as nutrients, biomass and mineral sediments are constantly accumulating.
The entry and sedimentation of organic and mineral material gradually leads to the growth of a sludge layer which is solidified by diagenesis and in which anaerobic or at least low-oxygen conditions prevail. Oxygen consumption can then occur, especially in times of high temperatures and falling water levels above the sediment . Perennial waters are often more affected by biogenic silting up than periodically dehydrated ones , since in the latter the biomass is ventilated, oxidized and finally made available again as plant nutrients in large parts of the environment.
The more anaerobic the mud at the bottom of a still water, the better it can demobilize certain nutrients and withdraw them from their availability, which is more likely to occur under water with rather low dry phases due to the exclusion of atmospheric oxygen. Longer dry phases (“ summer ” or “winter”) can therefore help to minimize the formation of sediments . If the accumulation of the sediment reaches the vicinity of the water surface, silting vegetation such as reed beds etc. can settle. The pond as pond silted then gradually, he that disappear over time and would thus lose its function (= "Auslandung" desludging) for lack of maintenance measures.
In the special case of a pond landing (desludging) beyond its actual bottom depth, the pond can no longer be drained completely without simultaneously lowering the monk and the drain, so that maintenance measures are then much more difficult by removing the deepened pond bottom from Sediments can only be freed under water or the dammed pond water along with the inflow water must be pumped out. Modern processes allow clearing under water (sludge pumps, etc.) - but due to the process-related liquefaction, complex measures are required (drying polders, etc.) for the treatment of the material (transport, etc.).
use
- Retention basin in the course of flood protection when draining receiving waters
- Raising and keeping fish ( pond management , e.g. carp ponds , trout ponds)
- Close-to-nature keeping of ducks and geese ( poultry production )
- Provision of drinking water for livestock (cattle troughs ) or people
- Provision of service and extinguishing water ( extinguishing water pond ) or snow-making water
- Water storage for energy generation through reservoirs and mill ponds , especially in mining e.g. B. Upper Harz water shelf ( artificial pond )
- Beautification and revitalization of gardens, parks , golf courses (village pond, ornamental, ornamental or garden pond)
- Swimming or bathing possibility (bathing or swimming pond )
- Dams for rafting ( raft pond )
- Purification of sewage (sewage pond )
- Extraction of plant fibers from industrial hemp or flax fibers ( roasted pond )
- Use as a horse pond (historical)
Ponds provide a habitat for a wide variety of plants and animal species.
Garden ponds
A garden pond is an ornamental and ornamental pond that usually has no technical significance. In most cases it has no inlet and outlet. Its water level is regulated by the amount of precipitation (rain) and solar radiation ( evaporation ). In long dry periods, it needs a supply of fresh water. For sealing see the detailed article foil pond . There are also prefabricated pools made of polyethylene or polyester.
Garden ponds are mostly created to beautify the garden, but also as an art object or for therapeutic purposes ( Kneipp therapy ). In addition, a pond offers a habitat for many animals and plants , see also biotope . You can use plants in all areas of the pond.
A garden pond can be created in different styles, for example as natural as possible, classic , modern or Asian with Koi . Ornamental ponds are traditionally stocked with goldfish . (but all ponds full of fish grow algae more quickly because nutrients are continuously brought in with the fish feed ). Ornamental ponds are becoming more and more popular and have even found their way into very small gardens. This is probably due to the high recreational value that distinguishes ornamental ponds; a small stream or even a fountain reinforce this effect.
Garden ponds are a comparatively clear and species-rich habitat , which is why they are also a suitable place for children to get to know new animal and plant species. On the other hand, small ponds are also dangerous for children, which is why children should not be unsupervised there. Wide, flat bank zones reduce the risk of accidents for children and drinking animals ( hedgehogs etc.). In the case of man-made water bodies, the owner can be held liable for accidents if the pond is not adequately secured.
The recommended minimum size of garden ponds is around 6 m²; that would be a pond the size of 3 × 2 m. The deep zone must be at least 70 cm so that fish and other animals can overwinter in the pond. A depth of 1.5 m would be better so that the pond does not overheat in summer.
In addition to other small bodies of still water, ponds can also be found in parks and on golf courses , where they serve as water reservoirs, playing obstacles or design landscape elements.
Fish are often released in ponds and other bodies of water. The often cited water birds with fish spawn in their plumage are very rarely the cause of spontaneous fish colonization, as the fish eggs are only able to adhere or survive for an extremely short time.
Inhabitants of ponds
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Ponds and their banks can be populated with different creatures or naturally populated, depending on the system and use, for example:
- insects
- Dragonflies with larvae
- Water strider
- Back swimmer
- Fire beetle
- Mosquito larvae
Apart from the artificial system, the deep zones and a lower wave impact, the ecosystems of many ponds are very similar to the lake ecosystem, depending on their size and management .
Material cycles
All forms of life in the pond are interrelated through material cycles. The plants extract carbon dioxide and nutrients (including phosphates and nitrates) from the water and use photosynthesis to form new biomass. In doing so, they separate oxygen , which initially remains dissolved in the water, but ultimately escapes as long as it is not consumed by breathing organisms. High oxygen concentrations can lead to gas oversaturation including the risk of gas bubble disease in the fish. Then bubbles form, with which oxygen and nitrogen escape from the water until a solution equilibrium with the air is reached.
The animals and, when it is dark, also the plants consume the oxygen dissolved in the water for breathing and excrete an equivalent amount of carbon dioxide. Because plants stop their photosynthesis in the dark, the carbon dioxide level increases at night while the oxygen level decreases.
The increase in carbon dioxide (CO 2 ) decreases the pH of the water. The lowest pH and the lowest oxygen levels are found in the early morning hours. In contrast, the highest values are found at sunset.
Vigorous movement of the water surface ( stream , fountain ) expels a lot of CO 2 from the water, while at the same time only little oxygen (O 2 ) is bound in the water. The most effective measure to increase the oxygen content is sufficient planting. Plant growth also reduces the available nutrient content in the water, thereby regulating algae growth. The underlying metabolic cycles correspond to those in aquariums .
Carbon dioxide ( carbonic acid ) dissolved in water is in equilibrium with hydrogen carbonate , which is created as water hardness when lime dissolves . The position and fluctuation range of the pH value are inextricably linked to the water hardness; Each time the hardness doubles, the pH range increases by 0.3 (= log 2).
Certain organisms (snails) remove lime from the pond, e.g. B. for the construction of their housing.
Due to the influx of "soft" rainwater, but above all due to the so-called biogenic decalcification, the water hardness of the pond water usually decreases over time. If, on the other hand, calcareous stones were used in the construction in or on the pond, the water hardness can also increase.
"Overturning" a pond
If a large part of the animals and plants in a pond suddenly die, this is often incorrectly referred to as " tipping over ". In a pond, such a catastrophe is usually due to an acute lack of oxygen. This is often caused cyclically by the oxygen consumption of a high biomass concentration (especially in algae ) and at some point falls below the minimum level necessary for survival. An above-average increase in algae is usually caused by an oversupply of nutrients in the pond. In the mud on the pond floor there are organic remains of leaves, pollen and food leftovers, which release the bound nutrients when the water temperature rises. This creates an oversupply in the garden pond, which provides a niche for fast-growing plants such as algae for unhindered growth.
Sometimes, however, only one algae population dies when its nutrients are exhausted. In still other cases, algae development is followed by the explosion of algae-eating zooplankton , which then eats up the oxygen-producing algae and uses up the remaining oxygen until it dies.
The hydrological definition of the term overturning is in reality not applicable to ponds, as it requires permanent stratification - see also eutrophication and sedimentation .
See also
literature
- Richard Bird: The perfect garden pond. Edition XXL, Fränkisch-Crumbach 2005, ISBN 3-89736-252-X .
- Max von dem Borne-Bernenchen: Brief instructions for breeding fish in ponds . Salzwasser, Paderborn 2011, ISBN 978-3-86444-186-8 .
- Wolfram Franke: The fascination of garden ponds. 6th, revised edition. BLV, Munich et al. 2000, ISBN 3-405-15067-1 .
- Franz Geldhauser, Peter Gerstner: Der Teichwirt: Carp and minor fish Ulmer, Stuttgart (Hohenheim) 2011, ISBN 978-3-8001-6962-7 .
- Peter Hagen: Pond construction and pond technology. (= Ulmer-Taschenbuch 62). 2nd, revised edition. Ulmer, Stuttgart 1995, ISBN 3-8001-6849-9 .
- Claus-Peter Hutter, Alois Kapfer, Werner Konold: Lakes, ponds, ponds and other still waters. Recognize, define and protect biotopes. Hirzel, Stuttgart et al. 2002, ISBN 3-7776-1189-1 .
- Norbert Jorek: Exemplary garden ponds. Ideas for building garden ponds, streams and water features. (The manual for planning natural, fish and swimming ponds, with experience from over 50,000 ponds.). 16th, completely revised edition. Nature and garden, Ibbenbüren 2004, ISBN 3-924564-04-3 .
- Friedrich Kögel, Harald Gebhardt, Mario Ludwig : Animals in the garden pond. Observe, recognize, settle. BLV, Munich 2004, ISBN 3-405-16712-4 .
- Klaus Kabisch, Joachim Hemmerling: Pools, ponds and ponds. Oases in our landscape. Landbuch, Hannover 1982, ISBN 3-7842-0255-1 .
- Richard Pott , Dominique Remy: Inland waters (= ecosystems of Central Europe from a geobotanical point of view. ). Ulmer, Stuttgart (Hohenheim) 2000, ISBN 3-8001-3157-9 .
Web links
Individual evidence
- ↑ DER SPIEGEL: Three siblings drowned in a pond - mayor condemned - DER SPIEGEL - Panorama. Retrieved February 29, 2020 .
- ↑ Fighting algal blooms - Gartenteich Ratgeber , 2016