Strange things found while mapping

I’ve just mapped a really weird-looking thing, and wondered if anyone knew what it was about (possibly a white elephant from the communist period?). It’s which is looks like it’s a canal for transporting water rather than for boats, that leads from near the lower end of a reservoir, for about 10km, as if it were taking it to be the water supply for something… and then just joins a river, which it could have got to by a much shorter route.

Having looked at where it joins the river, I can now make more sense of it; I think it’s taking water from the river to the reservoir, hence taking such a long route to go from upstream (where the river is at a higher altitude). The way it joins the river looks strange for an outflow (facing the wrong direction) so I think it must be an intake.