Watersheds and Impervious Surface

[ChristopherKodani]

Hi, I'm using ArcGIS Online to analyze some watersheds. I've been able to delineate them just fine, and want to know "how much impervious surface is in each watershed". It seems like Analysis-->Summarize-->Summarize Within would be the way to go, but every time I try, it gives back an error message.  My watersheds are shared with the public at http://arcg.is/2bD2hLT   The impervious surface area I want to use is the USA NLCD Impervious Surfaces 2011, which is easily available right through ArcGIS Online.

I've also tried this on Desktop, but the application freezes whenever I try to do anything. I think that the NCLD Impervious layer is probably just too big (covers 48 states!), or perhaps my computer is just too slow.

Thanks for any insight!

--Chris Kodani

[DanPatterson_Retired]

Yes, probably too big and input.  And I highly doubt that you would have had the great fortune for both files to be in the same coordinate system.... give that a check as well, because if they aren't there will be nothing to summarize because of spatial separation.