This confluence is located in the western part of the Southern Black Forest Nature Park below the so-called Höllental, where the Rotchbach flows through, and the Wagensteig valley.

The river leaves the Black Forest at the Freiburg soccer stadium called Schwarzwald-Stadion and continues flowing westwards.

The majority of the southern branch flows back into the Dreisam directly west of the Höllentalbahnbrücke bridge which is located in the Stühlinger district.

The northern branch of the river runs often subterraneously through the northwestern historic center of the districts Beurbarung and Brühl and flows westwards of Gundelfingen into Schobbach.

The aquifer, which consists primarily of solid rock, absorbs little water and hence leads to quick drainage, particularly in cases of heavy rainfall.

Even though the heaviest rainfalls occur in summer, the high water consumption of the local vegetation only leads to secondary drainage maximums.

Nowadays floods do usually not cause major damages since the Dreisam was secured on both sides through walls and channelized from Freiburg onward.

The drainage system of the Dreisam has many branches and can be characterized as a complex first degree river regime which is marked by two major discharges.

There are a couple of rivers that coalesce with the Dreisam, which are the headwater streams Rotbach and Wagensteigbach and (ordered towards downstream): Krummbach (which is also called Zastler Bach in the upper section), Brugga, Eschbach and Glotter.

The Dreisam is also of significance in the matter of individual traffic since on the south bank there are bikeways and on both sides motorways that lead to the city center of Freiburg and the “Zubringer Mitte” (highway 31a) to Beratzhausen.