[Tagging] waterway=river_channel

[Klaus Hartl]

I'd like to create a proposal about mapping whole (intermittent, [1]) 
river areas rather than just waterbodies. This enables the map user to 
see which area is affected by regular maximum water level of a river as 
well as the the area the river potentially moves crossways.



a cross section example of a river:


^^^---~~--~----~^^^
    |...........|


where:
^    natural=* / landuse=*
~    waterway=river
-    natural=gravel|scree|sand etc.
|.|  waterway=river_channel



Please have a look at: http://scrapy.net/osm/river_channel.png [2,3]
(not yet perfect, though maybe good to start off)


About the proposal: ..never done that. Could somebody tell me which 
templates how to use etc. or even wants to do that piece of work?


I think as a prerequisite it's necessary to know what terms to use as 
tag names and values.

. (main) river|stream channel
. river bed
. river bank
. floodplain
. etc, Compare to [4]


After that, but not yet of importance, my style suggestion was:
contourless area, filled with transparent pattern [5]


"Large flood-prone rivers often have extensive braided streams with 
large extents of river shingle, pebbles and bars above the normal 
water-level. At the moment there is no means of showing this in OSM. The 
existing tag natural=scree was used in the Philippines whilst mapping 
after flooding. This shows a quick hack (based on changes to the 
landuse=quarry render rules) to mapnik to show this tag." (SK53 [6])


Let me know what you guys think about that!


Cheers
Klaus


Sources and references:

[1] http://wiki.openstreetmap.org/wiki/Proposed_features/Intermittent_river
[2] 
http://uk.wikipedia.org/wiki/%D0%A4%D0%B0%D0%B9%D0%BB:Cross-section_of_typikal_terrase.png,
[3] http://en.wikipedia.org/wiki/File:Waimakariri01_gobeirne.jpg)
[4] 
http://www.slideshare.net/maliadamit/river-channel-processes-landforms-1026801
[5] http://scrapy.net/osm/scree.png
[6] http://www.flickr.com/photos/43047002@N06/4916724316/