Watershed delineation: Across several large DEMs?

Discussion created by rolanddeschain on Jul 15, 2011
Latest reply on Jan 1, 2012 by Playa

Thank you in advance.  Hopefully this is a simple issue:

My aim is to batch delineate watersheds for many points.  (I have been following these directions with no problem:

However, many of my watersheds cross DEM boundaries, rather than staying within a single DEM.

My goal: I want Arc Hydro to treat several DEMs (ideally the whole set--40 total) as one large unit, so that I can batch delineate all of my 70 watersheds in one fell swoop.  That way it would include the watersheds that cross DEM borders.

I'm not sure how to go about doing this, or if there is a better way.  I'm a bit skittish, because some of the terrain preprocessing steps (e.g., flow accumulation) take a long time, even for a single DEM... let alone dozens at once.

Again, thank you!