Hello, sorry if I use German terms, but the UI is in German and I expected to enter German terms. Regarding the big mess. My opinion is, that there was already a big mess before I did my edit. The river course is split into HUNDREDS of segments with lengths up to 10m criss-cross the actual watercourse. I just added the watercourse as a quite complete line according to the underlying bing maps images which should be not the very newest ones, but still more accurate than these river segments at OSM. I wonder if OSM wants to have historical watercourses and big detail or more updated data displayed. The river changes its course quite frequently. The details which the watercourse segments imply is deceiving.