[Talk-us] Proposed cleanup: NHD "rivers"

Paul Norman penorman at mac.com
Sun Mar 20 21:29:54 GMT 2011

A mapnik rendering change has revealed a problem in some areas with NHD
imported waterways. An example of the problem is at

Essentially, all the streams are tagged as waterway=river, with
waterway=stream being used for what appear to be intermittent streams.

I propose doing the following changes. These changes would *only* be done to
ways that have not been modified since import. I have experience with this
type change from cleanup on Canadian NHN data.
1. Adding intermittent=yes to NHD streams.
2. Downgrading waterway=river to waterway=stream for non-rivers. 
3. Joining rivers into a single way

Steps 1 and 2 would be done in one set of imports while joining rivers would
be done in a second pass. 

Spot checks in the area linked indicate this would cause no problems. If
verification with imagery was necessary I'd use MapQuest's Open Aerial Map
as it seems to be the highest quality in these remote areas. 

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