[Imports] NHD import process

[Mike N.]

> I get OSM files but the issues is that several entities have no names.
> How can I get them?

  In a few cases, the name is assigned to the relation instead of the water 
body.  For all other un-named entities, it would be like un-named ways - 
verify them by on site survey; occasionally the water body name will be 
posted on a bridge.   If the entity is large enough, it may appear in 
Wikipedia.    Beyond that, it is very difficult - you would need to rely on 
local knowledge, etc.

> The line file is empty. What is it supposed to contain?

  In some areas it will be empty.   In other areas it commonly contains 
dams.

> Are all of these useful and should all of these be uploaded?

  Everything in these files is thought to be useful and should be uploaded. 
Any filtering takes place in the scripts.

> Finally how can I merge various OSM files? I tried from JOSM but it
> takes forever.

  I've not found a good solution to this, other than JOSM on a 'horse of a 
machine', but it's still slow.   I usually spot validate several files 
against local knowledge or aerial shots, then upload them with 
http://svn.openstreetmap.org/applications/utils/import/bulk_upload_06/bulk_upload.py .