15 or 14 km before it flows into the Rhine. At 11,709 km², the catchment area of the Aare above the mouth of the Reuss is about as large as that of Lake Constance (11,487 km², outflow 78.4 km above the mouth of the Aare). Below the mouth of the Limmat, the mean discharge of the Aare is greater than that of the Rhine before the mouth of the Aare.
Of the Aare tributaries that arise in the Central Plateau, the southwestern ones collect in the Zihl. The others flow almost parallel to each other and flow into the Aare between Lake Biel and the Reuss.
The major tributaries from the Jura are shaped by the peculiarities of this limestone mountain range: the Orbe flows between its upper reaches in a valley bounded on both sides by the Rhone catchment area and the lower reaches through a sinkhole. The Areuse receives water from high valleys with no surface outlet through two lateral karst springs. The Schüss has its source in a karst area north of the Vue des Alpes pass and crosses various Jura gorges on its course. The Dünnern cuts a gorge in the Jura rock in the middle of its course and reaches the Mittelland near Oensingen.