Connecting Rivers

Posted by Reinhart Previano on 30 October 2018 in English (English)

False-color render of river A false-color render of Citarum river. Note that the unmapped line shown above is not geographically accurate.

Days after my attempts in extending the Citarum River, Indonesia (see this post), a HOT (Humanitarian OpenStreetMap Team) project added an unconnected part of the same river (highlighted in above image in dark blue color). Today, I have mapped the gap between both rivers to be joined into one in Changeset #64012348.

One thing that surprises me in the HOT changeset is that the river that flows in an opposite direction with my drawn rivers. I am confident enough to change the direction of the river to follow the direction of the dam in (-6.69206,107.41797) as well as the tributaries found at the unmapped part of the river (after the HOT changeset).

I am planning to do some QA on the HOT-added river before merging with the main river line.

Location: Cisomang Barat, West Java, Indonesia

Comment from rorym 🏳️‍🌈 on 30 October 2018 at 15:20

There used to be a QA tool that used contour data to see if a river was mapped as flowing uphill, and flag it as suspect. But I can’t remember what it was.

Comment from Carnildo on 30 October 2018 at 22:03

OSMI (, Osmose (, and JOSM’s validator will all warn if a river segment’s downstream node doesn’t connect to a suitable point. I think there may also be one that uses elevation data to find wrong-way flows, but I can’t find it.

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