The Acher is a 53.6-kilometre-long river and tributary of the

Rhine The Rhine ( ) is one of the List of rivers of Europe, major rivers in Europe. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein border, then part of the Austria–Swit ...

in the county of Ortenau, in the south German state of

Baden-Württemberg Baden-Württemberg ( ; ), commonly shortened to BW or BaWü, is a states of Germany, German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million i ...

. It flows in a northwesterly direction from the

Black Forest The Black Forest ( ) is a large forested mountain range in the States of Germany, state of Baden-Württemberg in southwest Germany, bounded by the Rhine Valley to the west and south and close to the borders with France and Switzerland. It is th ...

to the Rhine, between the two rivers; the

Rench The Rench is an eastern tributary of the Rhine in the Ortenau in Central Baden, Germany. It rises on the southern edge of the Northern Black Forest at Kniebis near Bad Griesbach im Schwarzwald. The source farthest from the mouth is that of ...

to the south and the Oos to the north.

Geography

The source region of the Acher lies on the northeastern mountainside of the Vogelskopf (), an area divided into

cirque A (; from the Latin word ) is an amphitheatre-like valley formed by Glacier#Erosion, glacial erosion. Alternative names for this landform are corrie (from , meaning a pot or cauldron) and ; ). A cirque may also be a similarly shaped landform a ...

s formed by the

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...

. The spring named the ''Acherquelle'' rises at a height of in the area of the ''Ruhesteinloch'', which is named after the Ruhestein Saddle to the east and is located between the Vogelskopf and Seekopf (). The Acher initially flows northwards, descending steeply. At its confluence with the Seebach, which joins from the north from the Mummelsee below the

Hornisgrinde The Hornisgrinde, 1,164 m (3,820 ft), is the highest mountain in the Northern Black Forest of Germany. The Hornisgrinde lies in northern Ortenaukreis district. Origin of the name The name is probably derived from Latin, and essenti ...

, it turns westwards and flows through the trough-like valley of Seebach. Here, the valley reaches a depth of about 550 metres between the Hornisgrinde and the Vogelskopf. In this section the Acher is also called the ''Seebach'', a clue that the

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

stream from the Mummelsee was originally the main headstream of the Acher, despite its somewhat lower discharge. Below the Vorderseebach, the Seebach merges with the ''Grimmerswaldbach'' from the north.The Acher valley then heads south for about a kilometre roughly to where the rugged Gottschläg valley, where the Karlsruher Grat and the waterfalls at the Edelfrauengrab above Ottenhöfen joins it. From the point where the Unterwasser valley joins from the south, the Acher continues in a northwesterly direction, flowing through the municipality of Kappelrodeck, to the

Upper Rhine Plain The Upper Rhine Plain, Rhine Rift Valley or Upper Rhine Graben ( German: ''Oberrheinische Tiefebene'', ''Oberrheinisches Tiefland'' or ''Oberrheingraben'', French: ''Vallée du Rhin'') is a major rift, about and on average , between Basel in the ...

, which it reaches in

Achern Achern (; ) is a city in Western Baden-Württemberg, Germany. It is located approximately 18 km southwest of Baden-Baden and 19 km northeast of Offenburg. Achern is the fourth largest town in the district of Ortenau (Ortenaukreis), aft ...

, the largest town of the northern

Ortenaukreis Ortenaukreis (; ) is a ''Landkreis'' (district) in the west of Baden-Württemberg, Germany. Neighboring districts are (clockwise from north) Rastatt, Freudenstadt, Rottweil, Schwarzwald-Baar and Emmendingen. To the west it borders the French Ba ...

. In the Rhine Plain, the course of the river has been made more complex by numerous hydro-engineering measures, especially the Acher-Rench Correction between 1936 and 1967. Even in the Black Forest foothill zone above Oberachern, the Acherner Mühlbach was cut short by the Acher at a weir, which has an average discharge here of around 5 m³/s. The Acher itself—also called the ''Feldbach'' in Oberachern''—''then crosses the borough of Achern and is finally led to the Rhine and

with some of its water (high water discharge) into the Acher Flood Control Channel. Just before the flood channel and the Acher divide, the Fautenbach joins it. The originally, partially canalised river runs northwards as the Acher ''(Feldbach)'' to Greffern. Before the construction of the Rhine Side Canal (''Rheinseitenkanal'') it emptied into the

here. However, the Acher has since been channeled into the Rhine Dyke (''Rheindeich''). A section of the Rhine Plain Canal used to pass under it coming from the west, being joined by the water-rich ''Sulzbach'', the lower reaches of the Sasbach and Laufbach as well as the Acherner Mühlbach. The Rhine Plain Canal then used to empty into the Acher itself from the east. Further to the north, the

Sandbach Sandbach (pronounced ) is a market town and civil parish in the Cheshire East borough of Cheshire, England. The civil parish contains four settlements: Sandbach, Elworth, Ettiley Heath and Wheelock, Cheshire, Wheelock. At the 2021 United Kingd ...

finally joins the ''Altrheinzug'' ("Old Course of the Rhine") as the lower reaches of the Acher are called. It empties below the

Iffezheim Lock The Iffezheim Lock () is a river lock on the Rhine near Iffezheim in Baden-Württemberg, Germany. The two passages of the lock serve to allow ships and barges to bypass the hydropower station on the French side of the river. It is one of the h ...

into the Rhine, around 10 kilometres below its old confluence. From Greffern the Acher is used as a link for the different areas of the Söllingen/Greffern Polder. In order to protect the Acher even when the

polder A polder () is a low-lying tract of land that forms an artificial hydrology, hydrological entity, enclosed by embankments known as levee, dikes. The three types of polder are: # Land reclamation, Land reclaimed from a body of water, such as a ...

floods, a

pumping station Pumping stations, also called pumphouses, are public utility buildings containing pumps and equipment for pumping fluids from one place to another. They are critical in a variety of infrastructure systems, such as water supply, Land reclamation, ...

near Greffern was brought into operation in 2005.Regierungspräsidium Karlsruhe:
Polder Söllingen/Greffern – Baumaßnahmen: Das Acherschöpfwerk mit Sielbauwerk – Bauwerk O.
' (retrieved 12 June 2011).

Protected landscape

Under the name ''Oberes Achertal,'' a

protected area Protected areas or conservation areas are locations which receive protection because of their recognized natural or cultural values. Protected areas are those areas in which human presence or the exploitation of natural resources (e.g. firewood ...

was created by the county council of Ortenaukreis around the municipalities of Ottenhöfen im Schwarzwald and Seebach covering 3,600 hectares. It is protected area no. 3.17.017 and was founded on 6 February 1975.

References

External links

More information about the Acher (in German) with pictures

Bibliography

*Britannica Atlas {{Authority control Rivers of Baden-Württemberg Rivers of the Black Forest Ortenaukreis Rivers of Germany