[Imports] NHD Duplicate data

Mike N. niceman at att.net
Thu Sep 10 13:50:48 BST 2009


Doing a routine pre-upload checklist, I found a case where there was a large
section of duplicate river overlap in adjacent NHD water basin extracts.
This was the Mackinaw river in sub-basins 07130003 and 07130004 .    This
becomes easier to see by loading the entire upload into JOSM - the
'flowlines' create a scatter plot that roughly follows the borderline on the
NHD download map.   But duplicates extend for a long distance outside the
primary sub-basin boundaries as indicated by the flowlines.

   I'm not sure what the best solution is; a program to detect duplicate
areas may not detect duplicates from an adjacent upload by a different
person.

 





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