I'm using a polyline river layer in QGIS to calculate river miles, but am ending up with points out of order. Starting with a river layer that is broken into reaches (short sections), I'm dissolving into a new layer based on the stream name. I am then calculating the distance along the line (I've tried two separate plugins, "Locate points along lines", and "Qchainage").
Unfortunately, some segments seem to be out of order, so the distance along the line jumps around, and sometimes go in opposite directions.
I end up with river miles that look like : The segment with miles 9-11 is between the segments with 0-5 and 6-8
I suspect this crops up in the dissolve stage because of some feature of the original data. Is there a way to dissolve the lines into sections that are continuous lines without misaligned segments?
Here is a link to the shapefile I'm working with. It's in a zip on dropbox. This version has been converted to single parts, with all the lines going in the same direction. zipped shapefile on dropbox