Aabachsee - Aabachsee
|Data on the structure|
|Height above valley floor:||40 m|
|Height above foundation level :||45 m|
|Height above the river bed :||43,2 m|
|Height of the structure crown:|
|Building volume:||1.350.000 m³|
|Crown length:||450 m|
|Crown width:||15 m|
|Slope slope on the air side :||1:1,3–1:1,7|
|Slope slope on the water side :||1:1,9|
|Data on the reservoir|
|Altitude (at congestion destination )|
|Water surface||1.8 km² (180 ha )|
|Reservoir length||max. 2.5 km|
|Reservoir width||max. 1.15 km|
|Storage space||19.5 Mio. m³|
|Total storage space :||20.5 Mio. m³|
|Catchment area||27,2 km²|
|Design flood :||53 m³/s|
The Aabachsee (also Aabachstausee is called) a reservoir behind the Aabachtalsperre in the circle Paderborn in North Rhine-Westphalia , near the border with Hesse , Germany . With an area of around 1.8 km², it is the largest lake in East Westphalia-Lippe .
The Aabach dam , which belongs to the “ Wasserverband Aabachtalsperre” and is part of an extensive water protection area as part of its dam , was built for the drinking water supply and flood protection ; The function of the Aabach reservoir as a recreational area is of secondary importance.
The dam, which consists of Aabach reservoir with pre- dam and Aabach dam, is located in East Westphalia between Bad Wünnenberg (Paderborn district) in the north-northwest and Marsberg (neighboring Hochsauerland district to the south) in the southeast and between the Sintfeld in the northeast and the Brilon Heights in the southwest.
The contact area of the dam is located in the upper area of the loosening zone of the Upper Carboniferous Arnsberg layers, an alternating layer of intensely folded fine sandstones , greywacke and clay and silt stones .  Due to the intensive tectonic stress during the Variscan mountain formation , the rocks were intensely specially folded. The area of the Aabach valley is also characterized by the presence of large fault zones .
The waterway in the mountain range was examined during the preliminary investigation and the construction phase by the Geological State Office of North Rhine-Westphalia using special test procedures ( WD tests ). The WD tests have shown that the increased waterways are mainly linked to crevices in the sandstone and Grauwacken banks. To improve the subsoil in the area of the blocking point, cement injections were carried out in 3 overlapping grouting rows. 
Immediately to the north of the dam, the folded Upper Carboniferous rocks are overlaid by Cretaceous marl and calcareous rocks of the Cenomanian and Turonian that plunge flat in northerly directions . The geological boundary between the Paleozoic and Cretaceous layers also forms the geographical and natural boundary between the Arnsberg Forest ( Sauerland ) in the south and the Westphalian Bay in the north.
The Aabach reservoir lies between the “ Fürstenberger Wald” in the east and southeast and “ Madfelder Wald” in the south at height. It is framed by elevations up to high as part of the Schweinsberg near the village of Bleiwasher ( near Bad Wünnenberg) ; 5 km south of the high skull rises .
The Aabach reservoir is fed in particular by the Aabach (also called "Aa"), which flows into its southern arm after flowing through the pre-dam of the Aabachsee, and by the Kleine Aa , which flows into the southeast arm, but also through Murmecke (southwest arm) and Haßbach ( West arm) as well as some other small streams. The reservoir is drained by the Aabach, which is a southern tributary of the Afte .
The Aabach reservoir, which has a maximum area of 1.8 km² when fully dammed, is around 2.5 km (distance south arm – dam) long and a maximum of around 1.15 km (distance south west arm – east bank) wide.
Of the total storage space of the Aabach reservoir, 3 million m³ are accounted for by the flood retention area and 17.5 million m³ by the operating room for the drinking water supply and the reserve and dead space. Every year around 11 million m³ of raw water are taken from the reservoir .
The Aabach dam was 2.85 km south-southeast of Bad Wunnenberg as a dam built from 1975 to May 1978; The district road "K 36" leads over the dam , which connects the Bad Wünnenberg districts of Fürstenberg in the northeast and Bleireinigung in the southwest. Their trial period lasted from April 1979 to June 1982. The dam was put into operation in 1983.
The dam was built as a zone dam with an inner core seal and a sealing carpet in front; it consists of hillside clay and heavily weathered siltstone . The bulk material required for the air- and water-side support body consists of low-weathering limestone , for the transition zones in this regard, weathered siltstone was used. There is an inspection passage under the sealing carpet on the water side .
The Aabach dam has a small pre- dam, the structure of which is similar to that of the main dam and which is around 430 m long and a maximum of 130 m wide. The Aabach coming from the south flows into the reservoir of the pre- dam .
At the site of today's Aabach dam and in the area of the Aabach reservoir directly adjoining it, there were around seven small fish ponds that were built over by the dam or flooded by the reservoir until construction began on the dam . In addition, the inn " Bumbams Mühle " , located on the old country road (Kreisstraße K 36) between the villages of Fürstenberg and Bleiwasher, was flooded by water, the walls of which can be seen when the water level is low Reservoir located "Bumbams Mühle think tank" reminds.
Together with the Aabach reservoir, the Aabachtalsperre provides drinking water for more than 200,000 residents in the Paderborn , Soest , Gütersloh and Warendorf districts, as well as flood protection and sport fishing .
The waters dammed by the Aabach dam are in particular Aabach , which also carries the water from the Großer Aa into the lake, Kleine Aa , “Murmecke” and “Haßbach”. The resulting catchment area is 28 km².
Over a transfer tunnel , the approximately 1.5 km long Karpke Ableiter , which was built as a gravity tunnel with a maximum capacity of 7 m³ / s, outflows from the 7 km² sub-catchment area of the east running Karpke river or from the Karpke retention basin ( ) into the southeast arm of the Aabach reservoir, into which the Kleine Aa flows.
The flood relief (device to protect barrier structures from high water levels) is located at the water-side dam foot as a 40 m high tower with an overflow funnel in the reservoir of the Aabach reservoir. It has a circular inlet funnel at the top, a vertical fall shaft and, after a 90 ° bend, leads through a tunnel through the dam into the stilling basin below or north of the Aabach dam . In addition to the flood relief, the extraction structure also contains the bottom outletand the operating outlets for raw water extraction with four extraction openings at different heights. As a result, the raw water can be taken from the height at which the water quality is best.
The Aabachsee lies in a natural landscape and is not very touristically developed; There are no settlements directly on the reservoir. It is surrounded by an approximately 9 km long, paved circular path that is used by hikers , cyclists and inline skaters .
Fishing is possible in some parts of the Aabach reservoir . The prerequisite for fishing is a valid fishing license and participation in the “information event on the fishing management of the Aabach dam”, which is held in March every year by the Aabach dam water association. Fishing licenses are issued in the local water board's waterworks .
Further recreational use is not possible because the reservoir and its surroundings are water protection areas.
Overflow funnel of the sedimentation basin
- Aabach dam water association
- Aabach dam Bad Wünnenberg
- Dams directory NRW (PDF; 122 kB)
- Dams in North Rhine-Westphalia; State Environment Agency NRW (PDF file; 121 kB)
- Karl-Heinz Ribbert, Klaus Skupin, Béatrice Oesterreich: Geologische Karte NRw 1: 25,000, sheet 4518 Madfeld, map and explanation , Krefeld 2008, ISBN 3-86029-155-6
- Friedrich-Karl Ewert: Investigations on rock injections , Münsterl. Research geol. Paleont. 53, Münster 1981, 1-326
- Peter Franke, Wolfgang Frey: Dams in the Federal Republic of Germany. Published by the National Committee for Large Dams in the Federal Republic of Germany (DNK) and the German Association for Water Management and Cultural Building eV (DVWK). Systemdruck-GmbH, Berlin 1987, ISBN 3-926520-00-0 .1