[Tagging] Lake or Pond

Kevin Kenny kevin.b.kenny+osm at gmail.com
Sat Jul 21 02:17:54 UTC 2018


>> Does light reach the bottom of the deepest point of the water body?
>> Does the water body only get small waves (i.e., smaller than 1ft/30cm in height)?
>> Is the water body relatively uniform in temperature?
>>
>> If these questions can be answered with a “yes,” the water body is likely a pond and not a lake.1
>>
>> Other national technical typologies do include a lower area requirement ranging from .5 hectares ( 'two NFL football fields' for USA residents ) to 2 hectares, and other various factors like inflow/outflow, relation to the water table, sediment suspension, etc.

I tag it all 'natural=water' and let other people worry about the
difference between a man-made pond and a reservoir and a flooded
basin. (I do use 'landuse=basin' for the ones that are only
ephemerally flooded.)

Otherwise, I'd go crazy with trying to label things in the complex
glaciokarst topography around here. Examples:

A 'lake' that is actually a permanently flooded ponor, with its outlet
an intermittent stream that flows in the wet season, and is rejoined
below the escarpment with several streams flowing out of cave
entrances, one of which is suspected to be the main drainage of the
lake.

A tarn or two.

A flooded kettlehole or two.

Large sporadic water bodies - some running to hundreds of hectares and
big enough to land float planes - that will be wet meadows in years
that the beavers aren't in residence. These are definitely impounded
reservoirs - but the impoundment isn't anthropogenic!

Reservoirs formed by anthropogenic raising of the water level of existing lakes.

And that's before we even get into trying to distinguish the things by
pH. (Acid bogs vs neutral-to-alkaline fens, etc.)

At least few people here are trying to distinguish based on area
alone. That's very good. If I want "waterbodies in excess of 10,000
m²" or whatever, I can compute areas from the geometries, thank you
very much. No reason to have separate tagging for just that!



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