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RGI 7.0: Missing drainage divides on Nevado Antisana, Ecuador #51

Open ezwelty opened 5 months ago

ezwelty commented 5 months ago

RGI version RGI v7.0

Describe the issue The outlines for the glaciers on the Nevado Antisana volcano in Ecuador appear to be missing drainage divides based on the elevation data that is available. I found this surprising because I thought that basins had been delineated automatically. Was this processing step not applied, and if it was, by did it give the result that it did?

Expected outcome More drainage divides following the clear ridges separating sides of the mountain.

Screenshots image

Maybe related to https://github.com/GLIMS-RGI/rgi_issue_tracker/issues/46

fmaussion commented 5 months ago

Thanks for the report!

Drainage divides are not done by RGI but by the analysts who are submitting data to GLIMS. The mapping team may use automated algorithms to help them out (Frank does), but it often requires substantial manual corrections afterwards.

In general, drainage divides are of variable quality in RGI7, but are generally better than RGI6 in many regions.

Central american glaciers have been flagged by A. Rabatel as "needing work", I think this outline is no exception (the divides are not the only issue here...).

Leaving this open for the record, but it wont be fixed before RGI8!