Prolongue rivers flow inside big lakes

@Timmy_Tesseract I see what you mean. This specific algorithm does correct for this; linear ways are not necessary here.

In some cases at least nearly everyone agrees that river is there and flows through reservoir.

See Zalew Włocławski - this case in particular is influenced by reservoir not being really wide, river being large and culturally important and there long before dam was created and other factors.

Interrupting river there would be inaccurate and misleading.

In general I would say that it depends and neither “always created named waterway lines” nor “always create unnamed waterway lines” nor “never created waterway lines” will work as rule here.


That’s fair, but at the same time there’s a huge difference between everyone agreeing that a river exits and flows through a reservoir and the actual reality of being able to map that an accurate or meaningful way. Kind of like everyone agrees there’s probably waterways under polar ice sheets, but you can’t really map them regardless. Or heck, underground reservoirs in natural aquifers. Same goes there. Do we all agree they exit? I think so. Does that mean they can or should mapped? No.

So if you feel for it, map it. If you don’t, don’t.

Yep, but the issue here are waterways navigable by boat or paddleboard and there are several mappers who think it makes sense to connect waterways leading into and out of a lake or reservoir and I cannot see any harm in doing so. No need to know the exact flowline of each individual way as long as the connections help in routing.

It surely makes not much sense in a huge waterbody like the Caspian Sea (as mentioned by @UNGSC-DTLM-Ale_Zena) which does not even have an outlet to navigate and may be questionable for others, but in general I don’t see any reason not to map it.


In this case there is definitely river there and you can for example identify the deepest part (where river was before dam was built). In other cases you may identify main stream or navigable channel or shortest connection or navigable channel or centerline of reservoir or something else that is treated by people as part of river on that section.

Underground reservoirs in natural aquifers are far more vague.

Not mapping Wisła there would be more far more inaccurate then any reasonable way of marking path of that waterway through reservoir.

Except it stops being the waterways once they enter the body of water. Otherwise be my guest and pick any big lake in the world and point out the waterway in it. Obviously you can’t. So it’s ridiculous to say people are navigating through waterways by way of the original waterway. As an example there’s a giant lake near where I live that has a large river on each side of it called the Sacramento River. No who navigates from one side of the lake to the other is like “I’m navigating the Sacramento River right now.” That would be stupid. They just say they are boating around the lake.

Nowhere I have claimed it causes any harm or that people shouldn’t do it though. I was actually pretty clear that people follow the standard if they want to. It’s just a super pedantic distinction without a purpose that literally no one in the real world follows. Again though, follow the standard and map waterways through bodies of water. I could really care less. I was just giving my opinion about why I think it’s a bad practice. Which the last time I checked I’m free to do.

Sure but realistically how many people are going to have access to that information or use it when they are mapping. Like you say underground reservoirs are vague, which I agree with, but realistically how clear is it for me or the OP to identify what the deepest part of a random lake is?

Yeah but then your not really mapping the waterway are you? Your just mapping your best guest of where you think it goes based an assumption that it must follow the simplest route between points. We could do that with literally anything. Really we do, like with estimating the shape of a building by at mapping as a rough square shape, and most of the time those types of edits are reverted because they are incorrect. That said, I have zero problem with someone mapping the shortest connection between two points of a river, but as a navigable route. Not as the actual waterway.

Waterway are actually not different from normal roads. It starts with basic vessal regulations. Such as allowable size and propulsion limits. No wake and other protected areas. Larger lakes usually have speed limits for everything from personal watercraft up to mutliperson boats with outboard motors. Then there is mapping water depth so vessels with a larger drafts such as sailboat don’t get stuck near small islands. It gets even more involved when lakes and rivers are large enough to contain shipping routes.

Did I say something that indicates I don’t know all that already in what you quoted or are you just citing random facts that have nothing to do with anything? Also, how does any of that relate to the discussion? So there’s basic vessal regulations, cool. I never said there weren’t, but whatever. How exactly does that relate to mapping waterways through large lakes?

Would it make sense to connect the “river” through a lake via a waterway=fairway ?

In some cases, where fairway exists and river is not considered to be existing: yes

That is how river course through man-made reservoirs was mapped in Poland in almost all cases.

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That is fine with me, i actually did the same.

Same with me … so apparently we share the same position … :+1: