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Recently it's been in the news that a major glacier has retreated dramatically due to climate change, and due to the topography it has stopped draining into the river it usually does, and started draining into a different river. This has effectively caused the first river to cease to exist. Here is a note on the subject, with some links to news articles. I'm not sure what to do about this, as we do not have more than a general description of the fact that this river has dried up. Additionally the area is pretty poorly mapped to start with, due to poorly done imports that are common in the remote parts of Canada. |
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The melt water from the glacier takes a new route but I would assume that localised rainfall events would produce an intermittent stream along the track downstream from where it rerouted and if not and it remains permanently dry, perhaps it could be marked as a gully. |
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Hi what about intermittent=yes to explain the wet and dry changes within the tagging scheme, together with a note=due to climate change no water/river/stream. And after some time you could simply delete the river from the valley as it no longer excist and would not become a river again. 1
I was under the impression that the
(21 Apr '17, 17:38)
keithonearth
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@Hendrikklaas : If the river has ceased to exist, then I do not think intermittent = yes is the right way to tag it. If it does not exist, it should not exist on the map either.
(21 Apr '17, 18:00)
mmahmud
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Hi, if something does not exist but is still on the map, you should simply update it by removing it. In the comment, mention why you removed and what is your source. But kindly be 100% sure that what you are updating is correct. I do not think this is a case were the river (or riverbed) no longer exists. The geographical features of the river banks and riverbed persists despite the source of the river's water flow being diverted elsewhere. Some other geophysical or human activity needs to occur to erase the river features. A few thousand years of erosion, or a large bulldozer flattening out the area might be needed.
(24 Apr '17, 07:12)
Huttite
It is said that the river has ceased to exist. If there are no river, why there should be on the map?
(24 Apr '17, 07:17)
mmahmud
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From the reports I have read, the riverbed still exists but the flow rate has reduced to almost nothing. The Slims river has not vanished, it just doesn't have water flowing in the channel at the moment because the glacier that feeds it has retreated so far that is is now preferring to flow into a different riverbed instead.
(See http://www.google.com/webhp?q=slims+river+dries+up+climate+change for a sample of news reports.)
Yes Huttite, that is my understanding. But I will add that, from the news articles I've read, it sounds like the flow has been reduced enough that it sounds like it should not be considered a river any more. Maybe an intermittent stream.
The note you refer to seems to be suggesting that we should be tagging for the renderer, rather than tagging to represent the reality that the water flow has reduced or dried up. Retagging as an intermittent stream may be better than nothing, but you probably still want to reflect where the old river banks are, since under flood conditions the stream would naturally flow between the river banks. With the river dry, you might also want to represent the landforms that now appear in the river bed, such as shingle banks and rock pools.