Hoe vind ik NED 30 die nodig is voor een stroomgebiedafbakening?

FaridAria

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Ik probeer een stroomgebied af te bakenen in Washington DC en ik heb NED 30 daarvoor nodig. Hoe kan ik het krijgen? Ik weet dat het te vinden is in National Map Viewer, maar als ik naar de downloadsectie ga, zijn er ongeveer 200 bestandsnamen en ik kan niet uitvinden welke ik moet downloaden.<\/P>

Bedankt<\/P><\/BODY><\/HTML>

ChrisDonohue__GISP

I'm not an expert on DEM's and their downloads, but here's some ideas based on my likewise flailing around on my infrequent downloads of them:

An idea - there are several options in Download Data section of the National Map Viewer.  One is "Click here to draw and download based on a bounding box."  This could help limit your selection.

Also, I believe the 30 meter DEM's match the same extents of USGS 24K Topo Quads (though I could be off on this).  This may offer another way to determine which ones you need - there is a reference layer that can be displayed for the 24k Quads.

Then the crux issue - once you go to the Download function, it returns a long list of different files, making it difficult to figure out which one needs.  I believe for 30meter DEM's the files you want to download are just the ones listed as "1 arc-second" under the Resolution column. However, I'm not 100% sure on that - maybe someone who is more knowledgeable can chime in on that?

Hope this helps,

Chris Donohue, GISP