Distinguish artifical water features from (semi)-natural water

[jeisenbe]

Expected behavior

• Provide mappers feedback by distinguishing (semi)natural water areas from artificial reservoirs, canals, ditches,

Actual behavior

• Streams appear similar to ditches and drains, rivers are similar to canals
• All water areas are the same color and lack an outline.
• Mappers have no feedback about missing water=reservoir and water=basin tags on artificial lakes, and landuse=reservoir / landuse=basin are not distinguished from natural=water lakes.

Possible solutions

• Add a lighter centerline for artificial waterway lines
• Add a darker outline for artificial water areas (reservoirs, canal areas etc): this would need to be done along with using a darker color for rivers to look right. For canals it would be difficult without pre-processing
• Subtle regular pattern for artificial water areas?

[imagico]

For waterway=stream/river vs. ditch/drain/canal i agree. See also #2346, #3354.

For artificial water areas - i am afraid the difference in meaning between the different tags is not very well defined for standing water (i.e. water=lake vs. water=reservoir)

Lake Victoria for example is tagged as water=lake:

https://www.openstreetmap.org/relation/2606941

despite being artificially level regulated and used for hydropower generation.

The Schluchsee OTOH:

https://www.openstreetmap.org/relation/1651189

is tagged as a reservoir. This is a perfectly valid choice of tagging but it is not documented how the line is drawn between a water level regulated lake and a reservoir and i am not sure if there is consensus about this in the mapper community.

In general i think solving #4128, #3895 and #3468 should have precedence over this.

[jeisenbe]

Re: Lake Victoria for example is tagged as water=lake: https://www.openstreetmap.org/relation/2606941 despite being artificially level regulated and used for hydropower generation.

I was not aware that Lake Victoria had a dam near it’s outlet. It’s worth noting that the dam does not appear to have been intended to increase the lack level, though 5 years after it’s construction the lake level unexpectedly rose due to heavy rainfal and after that, the operators chose to maintain the lake level about 1 to 1.5 meters higher than historical averages. However, it’s fair to say that over 90% of the lake surface was natural, and the current lake level and surface area is within the natural range of variation: https://web.archive.org/web/20060109075544/http://www.fas.usda.gov/pecad/highlights/2005/09/uganda_26sep2005/

So there seems to be nothing surprising about considering Lake Victoria a natural lake

In contrast The Schluchsee https://www.openstreetmap.org/relation/1651189 had a much smaller natural lake at this location, and the great majority of the current water area is created by the large dam: https://en.wikipedia.org/wiki/Schluchsee#/media/File:Schluchsee-Ursee.jpg - so it seems like mappers are choosing to call this a reservoir since most of the lake level and area is due to the dam.

In general i think solving #4128, #3895 and #3468 should have precedence over this.

I agree. This would be “nice to have” if it were easy enough to do, but certainly not the priority.