A nice stream I found in the forest (tweaking OSM import and river rendering).
Looking cool.
Those can be TORRENTS!
Usually empty of water and made from grey/white rocks and sediments.
With some tweaks you can use this algorithm for them. Saying average deep, wide, and changing the bed with some rock maybe.
A Torrents tool was always in my suggestions list. (some day i will post propperly if have some time).
And also tracks tool. Those little "roads" we see in the mountains. Sometimes natural by animals and sometimes by man.
My idea should be a tool modified from road (This you show can be a perfect begining for torrents and paths both), where you draw them using the real map superposition in Outerra. You can fill manually any mountain with paths and torrents (because this data is not avaible in osm or other vector source).
A system for upload this vector data from users would be covering more areas of the world step by step. Data can have divisions by areas, so a user can fill a total area which system can recognyze, without duplicating job between users.
Dont know if its dificult to implement upload data systems like that. But can be useful for more things in the future.
I say paths and torrents because they are a very important part of how some mouintains area look in real... If you imagine outerra big area with those accidents draw on them, the change in realism is dramatic.
PD: You can make torrents having the ability of transport water after a time raining.. )