Alright, here is the Wikipedia article on this bifurcation creek/river: https://en.wikipedia.org/wiki/Parting_of_the_Waters

As for continental Europe, two things come as relevant:
* Nerodimka river draining into Black and Aegean seas: https://en.wikipedia.org/wiki/Nerodimka_(river); and perhaps
* Danube sinkhole: https://en.wikipedia.org/wiki/Danube_Sinkhole connecting Black Sea and North Sea drainage systems

Further interesting reading: https://en.wikipedia.org/wiki/List_of_unusual_drainage_systems

@hanswolters

@hanswolters

Today was not in vain: I learned something interesting :-).

@FailForward While we are on the topic here is one of my favorite maps showing water ways (attached), the coloring is significant.

Each unique color represents a watershed, that is each color all drains out in the same direction and to the same point, ultimately draining to a single outlet into an ocean. You can always get from any point in the same color to any other point.

WRT a waterway which connects from ocean to ocean that would occur anytime there is a point that sits between two colors, almost always a lake, that drains off into each color in different directions. These lakes are special in the sense that they are the relatively rare waterways that belong to two or more watersheds.

#Nature #Rivers #water #watersheds #science

@freemo Thanks. Nice maps. Of course I know how drainage systems work, but I did not know there are natural connectors (you know, we built the Panama channel, but it would probably not "occur" on its own). On a second thought, though, it of course makes sense that occasionally Nature would produce such a thing. So to learn that there is such a creek (and more of such bifurcation rivers) is indeed interesting. And the split of the continent in the case of that creek is just so nice: right through the middle :-).

@FailForward They are in fact fairly rare if we are talking only natural occurrences. Only about two dozen such occurrences worldwide as far as I know.

@FailForward Not all of those flow into entirely separate oceans mind you, but they do bifurcate between different watersheds at a minimum.

@FailForward I was taught as a kid about river flows that empty into two separate watersheds (I had a strong ecology education in highschool and below). So while I knew there were about 2 dozen such occurrences worldwide I actually couldn't remember many of them.. So I tried to do some research and find a list to refresh my memory, i didnt find anything at first but finally just found this list, it looks fairly complete:

https://en.wikipedia.org/wiki/List_of_unusual_drainage_systems

@freemo It's not natural. Danube-Rhine channel is man made: https://en.wikipedia.org/wiki/Rhine%E2%80%93Main%E2%80%93Danube_Canal

@hanswolters Its a chart of watersheds.. each color ultimately flows into a single main river and a single outlet into the ocean.. so each color corresponds to one place water flows into an ocean.

I attached the german part of the map zoomed in for you.

@hanswolters Happy to help. (by the way not getting notified of these replies, but thats normal as I dont seem to be tagged. Even the OP likely isnt seeing your replies).

@hanswolters FYI if you took these maps and overlaid them on a topographic map you'd find there is a very close relationship between them. In all likelihood the boundary between the 4 main (largest) colored areas would have the ridge of a mountain running along it which divides the waterflow down either face. The larger rivers will almost always exist in the lowest lying areas as well, the valleys below the mountains.

@hanswolters In short, the rivers will tend to lie perpendicular to the altitude lines on a topographic map and generally grow larger the more lines they pass through.

@hanswolters I've always been a nature buff, I love this stuff. Its always way more complicated then we can imagine, nature is amazing like that.

@hanswolters
You mean probably South Holland, not Germany. https://en.m.wikipedia.org/wiki/Leidse_Rijn

Yes that story fascinates me as an example of big **voluntary and cooperative** infrastructure project in medieval times. Unlike elsewhere, where big projects were undertaken by an authoritative ruler, in South and North Holland villages and cities cooperated on joint solving of problems of downstream silting of the Rhine river. Downstream towns had a problem with river navigation and it could have been only solved father upstream. Without presence of a united region government control, that is not an easy problem to solve even nowadays - look at e.g., the problems in upper Nile. I've read about this in a book on history of the Poldermodel. Thanks for the reminder.