Illmensee (lake)

Illmensee
View of the south bank of the Illmen lake
Geographical location	Germany , Baden-Wuerttemberg
Tributaries	Andelsbach
Drain	Andelsbach →  Ablach →  Danube →  Black Sea
Places on the shore	Illmensee
Location close to the shore	Pfullendorf , Wilhelmsdorf
Data
Coordinates	47 ° 51 '19 "  N , 9 ° 22' 49"  E Coordinates: 47 ° 51 '19 "  N , 9 ° 22' 49"  E
Altitude above sea level	691  m above sea level NHN
surface	64,263 ha
volume	5,945,000 m³
scope	4.934 km
Maximum depth	16.5 m
Middle deep	9.2 m

The Illmensee is a lake southeast of the community Illmensee in the district of Sigmaringen in Baden-Württemberg , Germany .

geography

General

The Illmensee is the largest of three Ice Age lakes that form a lake district. To the northwest of it are the Ruschweiler See and the Volzer See . With reed and reed areas, the Illmensee measures 72 hectares. The actual water surface of the at an altitude of 691  m above sea level. Illmensee located at NHN is 64,263 hectares, with a volume of 5,945,000 cubic meters and a maximum water depth of 16.5 meters. The mean depth is 9.2 meters. The catchment area of ​​the Illmen lake covers 801 hectares.

Emergence

The Illmensee was formed towards the end of the last ice age, the so-called Würme Ice Age, around 18,000 years ago.

Since 1937 there has been a drop in the groundwater level of 1.3 meters.

Inlet and outlet

The Illmensee flows in and out via the Andelsbach , a tributary of the Ablach , which flows into the Danube . With a volume of 37 liters per second, the Andelsbach feeds the Illmensee on its southeastern bank. The drain is on the opposite north-west bank.

history

colonization

The Illmensee is where Neolithic pile dwellings were found . They are located in the shallow water area of ​​the west bank and on the east bank up to about ten meters from the tip of the peninsula, which is about 300 meters long, on average 25 to 30 meters wide and made up of up to seven meters thick layers of lake chalk . The first discovery reports come from pupils of the teacher E. Öxle in 1936. In the 1950s, today's soil monument was often the target of private research and the targeted collection of prehistoric finds. In 1980, the Illmensee was re-examined by the Baden-Württemberg State Monuments Office as part of the project to research wetland settlements on Lake Constance and in Upper Swabia. In the 1990s, the State Monuments Office initiated further inspections and a dive. Investigations of the ceramics allow an assignment to the Horgen culture ( Neolithic : 3000 to 2500 BC).

use

The land in the catchment area is primarily used for forestry or agriculture. The leaseholder of the lake is the Illmensee fishing association, which has leased the Illmensee from the Illmensee municipality as the owner and operates angling on the lake.

ecology

fauna

The Illmensee is rich in crayfish . When determining the fish population between 1990 and 1993 following fish species were found: eel , perch , bream , pike , crucian carp , carp , roach , rudd , tench , bleak , catfish and perch . According to Dehus, the population of roach, bream and perch is low compared to other lakes (e.g. Lengenweiler See, Schreckensee). Schools of young fish of perch use the vegetation-rich shallow water and reed belt zones. Since 1998, the Illmensee fishing association in cooperation with the Baden-Württemberg Fisheries Research Center has carried out an annual pike spawning fishery with trap nets, followed by stretching and releasing.

flora

The lake water is rich in lime, so that the lower growth limit is six to eight meters. The Makrophytenbestand has the following aquatic plants on: Rough Stonewort , Ceratophyllum demersum , Spateliges pondweed , Potamogeton perfoliatus (Occurrence: mainly in the shallow water areas) and comb-shaped pondweed , white water lily , Myriophyllum spicatum , Yellow Teichmummel , spreading the Water crowfoot , Canadian waterweed and Nuttall's waterweed .

The bank area is surrounded almost all around by a narrow belt of bushes and trees, to which gently sloping arable and meadow plots or smaller wooded areas reach. Broken reed belts can be found in the shallow water area.

sediment

The Illmensee has formed in a clay-rich limestone basin. The sediment was examined in 1992: phosphorus 1 mg / g DM, water content 71%, loss on ignition 9%. The average visibility is just 0.9 meters.

Water quality

In 1991 there were still four parts of Illmensee without a sewage treatment plant connection. This led to pollution of the lake. From 1970 onwards, numerous drained fen areas and intensively used agricultural areas on slopes also contributed to increasing eutrophication , the spread of macrophytes in the peripheral area and an increase in the anaerobic zone with H ₂ S odor. In addition, the inlet was straightened, but no buffer strip was created. As a result, around 145 kg of phosphorus were registered in 1991. Together with the entry via air and rain (31 kg), this results in a total pollution of 176 kg P / year.

The action program for the rehabilitation of Upper Swabian lakes launched by the Tübingen Regional Council in 1989 resulted in numerous rehabilitation proposals, some of which were implemented. All four sub-locations now have sewage technology, and rain overflow basins were built in 2002. In 1995 Albrecht Trautmann from the Ravensburg District Office created an extensification plan for the agricultural areas in the catchment area. In 2006 the extensive areas were already 30.3 hectares.

In 1994 the engineering office Funk from Riedlingen created a water development plan for renaturation . In 1996, the Andelsbach was renatured to 300 meters up to the mouth, and a floodplain of four hectares was created. In 1999 the renaturation progressed to the road to Mariahof, further renaturation is planned.

In 1998 Albrecht Trautmann created a bank maintenance concept for the lake. Neither algae blooms nor a sulphurous smell could be detected in the last few years.

Protected areas

The lake and shore areas of the Illmensee are part of the FFH area 8122-342 Pfrunger Ried and Lakes near Illmensee , which has a total size of 1723.5 hectares and is located in the districts of Sigmaringen with 996.4 hectares and Ravensburg with 727, 1 ha is located. The FFH area is a large moorland area with raised and intermediate moorlands, extensive, predominantly agriculturally used fen areas, small spring moorland and larger peat cut-off waters, as well as three natural lakes with silting moor in southern parts.

The three lakes were designated as Illmensee, Ruschweiler See and Volzer See by ordinance of the then Überlingen District Office of May 16, 1949 as a landscape protection area (protection area number 4.37.026). The LSG has a size of 263.1 hectares.

Economical meaning

Leisure and Tourism

Illmensee has been a state-approved resort since 1987. On the lakeshore there is a lido on the northeast bank, the "Seefreibad" and the "Camping Seewiese" right on the lake. In 2000 a nature trail about lakes was established. Since the Illmensee is a fishing and bathing lake, only the local DLRG association has a diving license here.

literature

• P. Dehus: Fish in Baden-Württemberg. The habitat of lakes and ponds . Ministry of Rural Areas Baden-Württemberg (ed.). Stuttgart 2000

Web links

Commons : Illmensee (Lake)  - Collection of images, videos and audio files

• Official website of the Illmensee community
• Illmensee Upper Swabian in action program for the rehabilitation Lakes
• Illmensee while diving in Germany
• Profile of the landscape protection area in the protected area directory of the LUBW

Individual evidence

1. ↑ Siegfried Volk (siv): Fish Jam at a weir in Andelsbach . In: Südkurier of April 24, 2015
2. ↑ List entry Illmensee - Illmensee ( Memento of the original from May 18, 2015 in the Internet Archive ) Info: The  archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. on UNESCO - World Heritage " Prehistoric pile dwellings around the Alps "
3. ↑ Cf. Olaf Brandt: A peninsula in the Illmensee . In the S. (Ed.): Illmenseer stories for the 150th anniversary of the Parish Church of the Assumption in Illmensee: Stories from young and old , ed. on behalf of the Illmensee municipality. Ilmensee 2010, p. 66 ff.
4. ↑ See Badischer Denkmalrat, Department for Prehistory and Early History (Ed.): Badische Fundberichte. Official news bulletin for prehistoric and early historical research. 14th year (1938).
5. ^ Jutta Stadelmann: List of prehistoric and early historical soil monuments in the district of Sigmaringen . In: Hohenzollerischer Geschichtsverein (Ed.): Hohenzollerische Heimat , 43rd year, No. 1 / March 1993 , p. 10 f.