Westfälische Aa

Course of the Aa, referred to as the upper reaches Johannisbach

The Aa ( rare: " Westfälische Aa " ), in the upper reaches Johannisbach, is a left tributary of the river Werre in the northeast of North Rhine -Westphalia.


The Aa is called to distinguish it from other (but also mostly located in Westphalia rivers with the name Aa) as Westfälische Aa. Your upper reaches ie Johannisbach. Johannisbach and Aa are hydro geographically identical and are continuously kilometriert, although lower and upper reaches are known in local parlance among the two different names and are therefore considered as two different rivers. The additional designation " Westphalian " is now uncommon in the local parlance as well as in card works. The Westphalian Aa Name ( Low Saxon Aue, Schleswig- smal Au, high German Oh, Ache, Achen or Aach, Old High German aha, Swedish A, Danish Å) means water or river and may be traced back to the Latin aqua. In the Middle Ages Aa was called " Hardna ".


The Johannisbach rises near Uerentrup in the Teutoburg Forest, west of Bielefeld passport. It first flows away in a northwesterly direction by a longitudinal valley of these mountains, from Bielefeld city center. In Großdornberg he leaves the mountains through an opening of the northern ridge, and only starts to flow north-east and then east through the Ravens Berger hills. He takes the coming of Werther Schwarzenbach on.

Below Schildesche the Johannisbach since 1982 is jammed to the upper lake ( river kilometer 14), also originally flowed into the Joelle by Joellenbeck in the north. Since 2009, the majority of the water of the locust stream is passed around in a Umflut around the lake. Directly in this Umflut now drained the Joelle. A little east of it crosses the railway line since 1847 Hamm- Minden on the Schildescher viaduct the valley of the locust creek.

In Bielefeld district Milse the Johannisbach combined with the coming from the south Lutter, who has previously taken the wind Woe three kilometers and is referred to from this point as Aa. Then the Aa flows through the district Brake and reached Herford, where it forms the border between the districts of Elverdissen on the right side and Stedefreund and Diebrock on the left. In the course of the Aa is the border river between Old Town and Field Mark Radewiger field mark, between Old Town and New Town Radewig and between Herford and Radewiger field marks. In the area Radewig / Neustadt Aa is dammed by two weirs. Here the moat branches off to the left of the district Radewig wraps around the west as opposed to the main arm. Shortly before the moat reunited with the main arm, opens from the right Bowerre in the Aa. After 26 km (8.6 km to the influx of Lutter ) Aa flows at the bridge Hansastraße in the Werre ( Werre km 22.5 ), while the museum MARTa Herford happens at the back just before the mouth.

Catchment area

Its catchment area covers an area of ​​254.5 km ². Due to the fact that Lutterbach and Johannisbach drain parts of the slope of the Teutoburg Forest, has the Westfälische Aa to a high flood potential.


On his way, the water takes downriver considered the following waters on:

  • Pader Bach ( L KM23, 5 L1 5 H? )
  • Twellbach (L KM23 L1, 5 H? )
  • Krebsbach (L KM22, 5 L1 5 H? )
  • Schwarzenbach ( KM18 L L10 H? )
  • Schloßhofbach (R KM16 L3, 3 H? )
  • Moorbach (L KM15 L4 H? )
  • Jöllenbecker mill creek ( Joelle ) (L KM13, 5 L9, 5 H? )
  • Lutterbach (R, KM9, L12, 1, H73 )
  • Jeipohlbach (L KM8, 7 ​​L2, 44 H73 )
  • Milsebach (R KM8, 2 L1, 064 H72 )
  • Seven Ponds Creek (L KM8 L2, 106 H71 )
  • Hellenbach (R KM7, 1 L3, 957 H69 )
  • Lubbenbach (L KM5, 8 L2, 377 H68 )
  • Eickumer mill creek ( Kinsbeke ) (L KM2, 7 L7, 45 H66 )
  • Flat Bach ( R KM2, 1 L2, 743 H65 )
  • Bowerre (R KM? L0, 12 H? )

(All lengths according Landesvermessungsamt North Rhine -Westphalia)


The upper Johannisbachtal is under protection (NSG Upper Johannisbachtal with side valleys ).


Aa or Johannisbach marked 1811-1815 the border between France and the Kingdom of Westphalia.

From 1939 to 1972, the Johannisbach was the northern boundary of the city of Bielefeld.