Flow Direction Problem on Island w/Ocean Body.

Discussion created by drecsoo on Mar 31, 2012
Hi -

I am trying to run Flow Direction on a filled 30m DEM on the East End of Long Island (NY), but am having trouble understanding the results in the adjacent ocean body area (i.e. Atlantic Ocean).  I have attached a couple of screen shots to illustrate these artifacts.  My flow direction results will also impact my Flow Accumulation results (and subsequent steps).  How can I resolve the issue of having large water bodies surrounding the land surface that I am interested in modeling?  How is the tool actually calculating flow direction in the ocean area?

Any advice is greatly appreciated.

Thank you!
Andrea Soo
West Chester University