Hafnersee

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Hafnersee
Keutschach Plescherken Hafnersee Schiefling Gerlitzen 26022008 04.jpg
Hafnersee with a view of Schiefling and the Gerlitzen
Geographical location Keutschacher Seental , Carinthia , Austria
Tributaries Rakoutzabach, outflow of the Penkensee
Drain Hafnersee outflow → Keutschacher See
Location close to the shore Schiefling
Data
Coordinates 46 ° 35 '15 "  N , 14 ° 7' 58"  E Coordinates: 46 ° 35 '15 "  N , 14 ° 7' 58"  E
Hafnersee (Carinthia)
Hafnersee
Altitude above sea level 508  m above sea level A.
surface 15.939 7  ha
volume 795,224 m³
Maximum depth 10 m
Middle deep 5 m
Catchment area 12.7 km²
Template: Infobox Lake / Maintenance / EVIDENCE AREA Template: Infobox Lake / Maintenance / EVIDENCE VOLUME Template: Infobox Lake / Maintenance / EVIDENCE MAX DEPTH Template: Infobox Lake / Maintenance / EVIDENCE MED DEPTH Template: Infobox Lake / Maintenance / EVIDENCE Catchment Area

The Hafnersee ( Slovenian Habnarško jezero ) is one of several lakes in the Keutschacher Seental south of the Wörthersee ( Carinthia ).

geography

The lake is located in the Keutschacher Seental in the area of ​​the Sattnitz , which owes its origin to a branch of the Draugletscher . This has reshaped the tectonically pre-formed valley furrow. The Hafnersee is located 800 m west of the Keutschacher See . The subsoil consists of old crystalline rock series ( phyllite , mica schist , limestone marble). Above it are clayey deposits from the Young Tertiary, 40 to 50 m thick. The 400 m thick Sattnitz conglomerate (recent Pleistocene ) lies on top of these .

The Hafnersee has two tributaries, the Rodabach, the Schiefling and Techelweg drains, and the outflow from the Penkensee lake to the south . The proportion of groundwater is quantitatively significant.

In the west of the Hafnersee there are extensive flat bogs through which the main tributary of the lake runs. Due to the humic acids that come from the moor, the lake has a natural brown color. The east bank is also flat, here the Rakouza or Rodabach rises, which flows into the Keutschacher See. There are only small silted areas on the north and south banks.

The area of ​​influence of the lake is 12.7 km² and consists of the western part of the Keutschacher Seental, the northern slope of the Turiawald and the southern slopes of the Wörthersee mountains.

The Hafnersee is oblong and rectangular. In the middle, the lake basin is separated into two sub-basins by a shoal that is only 1.8 m deep. The western basin is 10 m deep, the eastern 9.1 m.

history

In 1974 a neolithic pile building was discovered on the central shoal of the lake. It is dated in the temporal context of the Mondsee culture in the Salzkammergut. This Hafnersee wetland settlement is a listed building .

Hydrology and ecology

The mean discharge is 240 l / s. The water renewal time is 1.2 months.

The water temperatures of the Hafnersee are similar to the Keutschacher See. The temperatures regularly reach 25 ° C. The temperature peaks are reached in the second half of July. From the end of November to March the lake is often frozen over, the ice thicknesses reach 40 to 50 cm. From May to October the lake is strictly stratified, but due to its shallow depth, no typical hypolimnion can form. The temperature above the lake bed is over 10 ° C in summer. The mixing of the lake water (circulation) takes place in spring in March / April, in autumn in November.

The lake water is medium hard with around 10 ° dH. This is due to the lime-rich catchment area. The electrical conductivity is 330 to 420 µS / cm.

The lake is currently classified as weakly mesotrophic. The average total phosphorus content is 12 to 14 mg / m³. In phytoplankton prevail Dinobryon divergens and Cyclotella ago. Pediastrum duplex is strongly represented in summer . 21 species of rotifers , 6 species of copepods (especially Eudiaptomus gracilis ) and 7 species of water fleas ( Bosmina longirostris , Daphnia hyalina , Daphnia cucullata and Ceriodaphnia pulchella ) are represented in the plankton .

The dense settlement as well as the intensive agricultural and tourist use of its catchment area led to a high nutrient load of the lake ( eutrophication ) in the early 1970s . The strong growth of the floating algae made the water very cloudy. In 1974 and 1975, nutrient-rich and oxygen-poor deep water was sprayed onto the surrounding areas by means of pumps. The installation of a deep water drainage was forbidden because of the associated pollution of the downstream Keutschacher See. In 1974, 1975 and 1977, at the end of summer stagnation, the water was oxygen-free below 5 m. The algae biomass was extremely high between 1971 and 1976 with up to 20.5 g per m³ in the epilimnion . The biomass was mainly formed by Asterionella formosa (diatoms). From 1974 the sewage system was built in the Keutschacher Seental, which was essentially completed by the mid-80s. Since then, the wastewater has been cleaned in the Klagenfurt sewage treatment plant . Since 1985 the situation of the lake has improved. The total phosphorus concentration in the epilimnion fell from up to 62 µg / l to below 20 µg / l, the mean algae biomass to 2 g / m³ (values ​​1990/1992). The oxygen levels rose, the depth of view increased.

The south bank in particular is natural. A large number of small organisms find good living conditions here. Water snails, mussels and numerous insects live in the underwater plant population.

The lake is part of the 2,532-hectare nature sanctuary Keutschacher Lake Valley  ( LSG.032 , 1970).

use

The lake is used as bathing water. There are sunbathing lawns and bathing areas on the north bank. There is a campsite on the northeast bank.

Animals in the Hafnersee

The Hafnersee has a great abundance of fish. There are 19 species of fish:

The North American largemouth bass is a neozoon . The original main fish, the white bream , has declined sharply in recent years. There are populations of the noble crayfish ( Astacus astacus ) in the bank area and at the drainage . The crabs can be found both in the bank areas and in its drain, the Rachunzabach .

Only sport fishing is practiced at Hafnersee.

See also

Web links

  • Hafnersee , Carinthian Institute for Lake Research

Individual evidence

  1. ↑ a b c d e f g h i Hans Sampl: Lakes and ponds of the Keutschacher Seental . In: Bettina Golob, Helmut Zwander (eds.): The Sattnitz. Conglomerate of nature in the south of Carinthia . Natural Science Association for Carinthia , Klagenfurt 2006, ISBN 3-85328-041-2 , pp. 29–44.
  2. ↑ a b c d Carinthian Institute for Lake Research: Carinthian Lake Report 1992. 60 years of lake research, 30 years of lake restoration . (= Publications by the Carinthian Institute for Lake Research 7) Klagenfurt 1992, pp. 399–415.
  3. ↑ 14 C dating 4460 BP; Mondseekultur 4940–4310 BP Tab. 1 14 -C Dates of the Neolithic and the Early Bronze Age in Austria . In: Herwig Friesinger, Walter Kutschera, Peter Stadler, Eva Wild: Absolute Chronology for Early Civilizations in Austria and Central Europe using 14 C Dating with Accelerator Mass Spectrometry ( Homepage ). Project, QAM Quantitative Methods in Archeology, 14 C Theory and Practice , on winserion.org.
    Maximilian O. Baldia: Mondsee C14 Dates. comp-archaeology.org, 2001, archived from the original on December 11, 2007 ; accessed on October 24, 2007 (English). Eva Lenneis , Christine Neugebauer-Maresch , Elisabeth Ruttkay : New Stone Age in Eastern Austria . (= Scientific publication series Lower Austria 102/103/104/105). In: Research reports on the original and Early history . No.
     17 . Lower Austrian Press House u. Verlagsgesellschaft, St. Pölten / Vienna 1995, Tab. 1 The u C data on the Neolithic and the Early Bronze Age in Austria , p. 210-224 ( pdf , p. 10).
  4. ↑ a b c Hafnersee on the website of the Carinthian Institute for Lake Research , accessed June 19, 2011.