The Rhine river basin is dealt into nine – mostly international - sub-basins, all depending on hydrographical and natural characteristics. The main stream Rhine and its tributaries have been divided into six sections (Alpine Rhine / Lake Constance, High Rhine, Upper Rhine, Middle Rhine, Lower Rhine, Delta Rhine). The three largest tributary areas – Neckar, Main and Moselle-Saar are separate units. In these sub- basins the different countries and German Länder involved or the regions concerned agree upon all questions relating to water management on a transboundary level.
The water quality and ecology of the R. Aare is being coordinated in the area of operation High Rhine.
that parts of the waters of the Upper Danube flow into the Rhine?
At several points, the European water divide between the Danube and the Rhine is being avoided, as at the percolate of the Danube at Immendingen.
"The Rhine unites everything. It is as rapid as the R. Rhône, as large as the R. Loire, as enclosed as the Moselle, meanders as the R. Seine, as clear and green as the R. Somme, as historic as the R. Tiber, as royal as the R. Danube, as secret as the R. Nile, spangled with gold as a river in America, covered by legends and ghosts as an Asian river.”
(Victor Hugo, 1842)