[Imports] [Talk-us] NHD data changes

[Toby Murray]

On Sat, May 5, 2012 at 9:19 PM, Paul Norman <penorman at mac.com> wrote:
> I've been looking at the NHD data from the USGS site and have noticed a few
> recent changes from how they were described on the wiki.
>
> 1. The viewer has changed. http://viewer.nationalmap.gov/viewer/nhd.html
> will bring up a map you can use to download NHD data. This viewer does not
> work in Chrome but does work in IE. Subregions are pre-staged downloads, the
> others will take some time before you can download.
>
> Subregions can be directly downloaded from
> ftp://nhdftp.usgs.gov/DataSets/Staged/SubRegions/PersonalGDB/HighResolution/
>
> Most subregions are available as a new NHD 931v210 file but some are still
> being generated.
>
> 2. NHD data is now available only as File Geodatabases (File GDBs, .gdb) and
> Personal Geodatabases (Personal GDBs, .mdb). My understanding is the default
> builds of QuantumGIS and GDAL on Windows can open Personal GDBs.
>
> On linux gdal can be compiled with drv_mdb or the pgeo driver can be used
> for Personal GDBs, or the filegdb driver can be used for File GDBs. This is
> moderately technical.
>
> 3. The NHD attributes changed with NHD v2.1. All the old mappings of NHD
> FCodes to OSM tags are outdated. For rivers and streams nothing has changed
> but others have. I haven't found a list of the 2012 changes.
>
> The two current FCode lists I am aware of are
> http://nhd.usgs.gov/userGuide/Robohelpfiles/NHD_User_Guide/Feature_Catalog/H
> ydrography_Dataset/Complete_FCode_List.htm and
> http://nhd.usgs.gov/NHDv2.1_poster_3_23_2012.pdf
>
> If you are planning something where you will be checking each object's
> tagging this will not affect you too much, although you may encounter more
> objects you have to retag.
>
> If you are considering proposing any kind of NHD import where you don't
> check each option I suggest you wait.
>
> I am working on a translation file but it takes a fair amount of time. There
> are a *lot* of FCodes and I need to look at some of each in multiple areas
> to see the appropriate tagging. Not all FCodes appear in all areas and what
> seems appropriate in one area may not be for all areas.

Thank you for your work on this. NHD hasn't been high on my priority
list but I might actually try to use some of it around here once you
get things in a working state.

Toby