I started looking at the Rann of Kutch in India, and it doesn’t look very well mapped. I also can’t find any mentions of it on the wiki, or Googling for “Rann of Kutch” in conjunction with OpenStreetMap.
Christoph Hormann’s post is the only thing I can find: http://blog.imagico.de/new-images-for-mapping-in-osm/
Does anyone know if there’s been any previous discussion (perhaps on the
talk-in list?) about how to tag it? Or does the local community prefer it this way?
Here’s what it looks like now:
Which looks very different from the image in Christoph’s blog:
He notes in another post that it’s the largest area of incorrect coastline in the world, according to his metrics: http://blog.imagico.de/osm-coastline-and-glacier-data-quality-reports/ His map shows that most of the coastline in that area hasn’t been touched in OSM since 2007:
According to Wikipedia, this area is only submerged during the monsoon season, and is dry the rest of the year. So it seems like the correct tagging would be to move the
natural=coastline further out, and most of the currently wet areas in OSM should be retagged as
wetland=saltmarsh (see wetland=saltmarsh) on the wiki. But I don’t have any local knowledge, so I’d want to be sure about that.
Here’s an overpass turbo query for
natural=wetland in the area:
There are four large polygons (one is a multipolygon relation, actually), all four of which have
natural=wetland but no additional tags… no
wetland=saltmarsh that I was hoping for. And mostly these features cover the current OSM land, not the incorrect water areas anyway.
I also did an overpass query for
wetland=* just in case there were any polygons that had
wetland=saltmarsh (or similar) and which might have accidentally left off the
natural=wetland tag. But no luck, there’s basically nothing using
wetland=* that’s useful:
As a last resort, to see if there are any OSM features we can work with (perhaps someone is using non-standard tags), I zoomed into a bit of the India/Pakistan border near the coastline. There is a line of barrier islands that probably mark the true edge of the Great Rann of Kutch, which is where we should see any hidden features, if there are any. Here’s the data overlay layer: http://www.openstreetmap.org/#map=12/23.7720/68.2019&layers=D
Finally, if I zoom in enough to edit, we see that the satellite imagery is good enough that someone could trace the correct edges of the salt marsh… but it would take them a bit of time to do it well.
Does anyone have any thoughts or experience with this area?