[Talk-us] USGS National Hydrography Dataset
Alan_Mintz+OSM at Earthlink.Net
Wed Mar 2 23:54:32 GMT 2011
At 2011-02-17 22:21, Toby Murray wrote:
>On Fri, Feb 18, 2011 at 12:09 AM, Val Kartchner <val42k at gmail.com> wrote:
> > On Thu, 2011-02-17 at 08:57 -0500, Phil! Gold wrote:
> >> (TopOSM also shows a lot of intermittent streams from the USGS National
> >> Hydrography Dataset.)
> > Can we get this USGS dataset loaded? It would be more accurate than
> > tracing from satellite images, and much quicker too.
>It has already been imported in some areas. Check the "Basins and
>per-basin sign-ups" section on the above page for details. There has
>not been an effort to do a nation-wide import though. As I understand
>it, the tools have been provided for local people to do it on their
>own. I have been meaning to look at this for Kansas...
Do look carefully at the results. In some places in the central/high
deserts of CA, the NHD contained many thousands of poorly-connected streams
that rarely seemed to correlate with actual features in surveys or
satellite imagery. A lot of this is the nature of water in the desert - it
tends to be very thin and to move around over time. The result was trouble
with object density and download sizes, server throttling violations, all
with no real benefit.
Alan Mintz <Alan_Mintz+OSM at Earthlink.net>
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