Gregory's Server
@amapanda Roman in the russian group shared this article: https://habr.com/ru/articles/830334/
It's in Russian, but deals with determining the best width for a river to be displayed on a map, which I think relates to the flow measurement you did (based on distance).
"Скорость течения" means "flow speed", for pictures.
@zverik that's cool.
I'll have to look at some of the plugins.
`osm-lump-ways` did try to calcaulte Strahler numbers, but lots of rivers are “braided” (splitting & rejoining) so the standard algorithm gave “incorrect” results.