Back in April in http://lists.openstreetmap.org/pipermail/talk-ca/2011-April/003929.html I proposed importing data from Surrey, BC to replace the current OSM waterway data for the city, which is derived from a NHD import. The license and accuracy of the data is not an issue, the only questions that arose were around the mapping of roadside drainage ditches.
The accuracy of the Surrey data is unquestionably better than the existing OSM data. The NHD data includes streams that were paved over 25 years ago. In summary, the import would consist of four categories. 1. Streams. These typically meander, are in forested areas, are natural, and have names. They are often nutrient-bearing for fish. 2. Rural and agricultural ditches. These are long, straight, and sometimes have culverts. 3. Ditches in suburban areas. These are broken up by culverts and eventually drain into the storm drain system. 4. Culverts. These are in a separate file, and join the breaks together. At the time, no one was certain if adding ditches would cause the area to be unwieldy to edit. Over the last couple of days, I have been mapping in Queensborough, an area with very similar ditches. http://www.openstreetmap.org/?lat=49.19043 <http://www.openstreetmap.org/?lat=49.19043&lon=-122.9372&zoom=17> &lon=-122.9372&zoom=17 is the area. Ditches can be found on Lawrence, Wood south of Ewen, Boyne, Pembina north of Ewen, Fenton and Johnston. I have found that the ditches are not a problem when editing the area. Adding the ditches takes some time to correctly split at culverts, but the ditches to be import are already split. The blue waterway=ditch lines are subtle on the gray landuse=residential background and not overwhelming. I also looked at the osmarender and Open Mapquest renderings, as well as an assortment of cloudmade renderings. What I propose to do is process updated versions of the files and post them for review. I have some old sample waterways at http://maps.paulnorman.ca/surrey/samplewaterways.osm but additional work is required, and I intend to use the latest shapefiles. The waterways will be tagged with start_date, source, waterway, an ID in the surrey:* namespace and the nutrient/fish status in the surrey:* namespace. The nutrient/fish statuses are documented on http://cosmos.surrey.ca/Geocortex/EssentialsExternal/Web/Metadata/metadata_e xternal.html#drnFishClassifications (broken HTML may be present)
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