"The city stream is redirected in an underground, invisible loop so that it flows backward, or upstream, for a short distance. However, the backflow is always j

"The city stream is redirected in an underground, invisible loop so that it flows backward, or upstream, for a short distance. However, the backflow is always just outflow in reality. This is because the watercourse has a continuous gradient." (translated from a Google result excerpt of this paywalled article [0]) [0] https://www.derbund.ch/warum-der-stadtbach-aufwaerts-fliesst-146217667794 https://www.derbund.ch/warum-der-stadtbach-aufwaerts-fliesst...)