Möhlin (Rhine)
The Möhlin in Breisach
The Möhlin is a small, 32 km long tributary of the Rhine in the area of the district of Breisgau in the Black Forest. The name may be of Celtic origin; an oppidum is occupied archaeologically on a tributary of the Möhlin.
The Möhlin springs on the western slope of the Schauinsland Massif above Sankt Ulrich in the Black Forest of several talus sources. The main source is located about 500 meters northeast of the Gießhübel 1080 m above sea level. NN. Over time, the river has cut into the upcoming Anatexit and formed a steep V-shaped valley with an average gradient of about 12 ° from. It flows in a northwesterly direction and is passed after 200 meters below the county road K 4957.
The natural upper reaches flowing through Bollschweil at the foot of the Black Forest and reaches churches honor the Rhine valley. Upon exiting the Möhlin from the mountains in the Rhine valley lost through seepage water. In response to the discharge the seepage makes up to 15% of the total volume. Already on the territory of the city of Bad Krozingen, just above the local part Biengen, where the mostly more water flows into the leading Neumagen Möhlin, the river is strongly channeled. The construction of the weir culture Breisach in 1965, the original mouth was moved to below the weir.
The wing dam of the Rhine dam crosses about 600 meters abeam from the Rhine Möhlin. At the intersection of a weir with a clear opening of 18 meters has been built with segment closure in Möhlin. In case catastrophe about 500 m³ / s must be dissipated by the Möhlinwehr. The opening track of Möhlin below the weir had therefore to be expanded to 1.8 km in length for this drain. In addition to the discharge of the flood disaster that Möhlinwehr has the task of eliciting the lowest water levels using the rotating shutter above the weir. Thus, the developed an outflow of 500 m³ / s Möhlin not the groundwater to be lifted by the weir drains, 400 m above the mouth of the Rhine was built in Möhlin a fixed threshold with fish ladder. The level of the threshold is chosen so that an optimum water level can be ensured above the threshold.
Not least because of intensive agriculture in the Rhine valley falls Möhlin dry on its middle reaches in hot summers. Conversely, the more tranquil river swell dangerous during heavy rainfalls or sudden snowmelt.