[Imports] NHD Data Import

[Clifford Snow]

On Sat, May 8, 2021 at 11:10 AM <grussausbw at gmx.de> wrote:

> Hello, i'm Hiausirg (https://www.openstreetmap.org/user/Hiausirg)
> I've been mapping along railroad tracks for the last few weeks, and I've
> noticed that there are a lot of missing lakes/ponds etc. in the rural
> areas. Drawing them manually is very time-consuming, so I thought that it
> would be faster with an NHD
> <https://wiki.openstreetmap.org/wiki/National_Hydrography_Dataset>
> import.
> For this purpose, I have selected a smaller data set (compared to others)
> in the area in which I am currently editing, and prepared it for import. This
> is the data set
> <https://www.sciencebase.gov/catalog/item/5a58a424e4b00b291cd68491>. I
> have imported it into JOSM and prepared it for import. I converted all USGS
> tags to OSM tags, matched everything with current aerial images, deleted
> non-existing stuff, and so on. Every water spot/swamp was checked MANUALLY.
> Then I matched it to already existing data. There were about 500 lakes in
> the area, with my import there would be ~3000. 137,000 total objects
> (Nodes/Areas) would be added, 6200 deleted (these would be replaced with
> higher quality NHD data).
>
>
> In a nutshell: The data is high quality and I just have to press the
> upload button. After all, NHD data was uploaded ten years ago *and *i
> reviewed everything manually: Do I need to do anything else now except wait
> for an ok here? And should i create a seperate account to do this?
> By the way: Here
> <https://www.mediafire.com/file/3wnr6d02w4w5r2l/NHD.osm/file> is the data
> that *i* want to upload.
>
>
NHDPlus [1] data is better quality. I'd recommend looking into using it.

As Kevin Kenny recommends adding small sections is the best way to go. What
I've found is that the NHD data doesn't do a great job of matching the
streams using current imagery. I'd encourage you to update the stream to
match more recent imagery. In my area many of the streams are intermittent
and it's not clear where or how they cross roads. I'd avoid adding those.
Also check out the FCODES of the streams to spot ditches and pipelines.
QGIS is a great and free tool to visualize streams and you can color code
different FCODES.


[1]
https://www.epa.gov/waterdata/get-nhdplus-national-hydrography-dataset-plus-data

Best,
Clifford

-- 
@osm_washington
www.snowandsnow.us
OpenStreetMap: Maps with a human touch
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