There is a structure that appears on rivers everywhere, that most people cannot name correctly, and that does something quite different from what it appears to do.
A weir looks…
The useful thing to understand is that a crossing point is not a convenience but a bottleneck. Every route in a region funnels toward the few places the river can…
Source :Wikipedia
Look at a river from the air and it does something that ought to require an explanation. Water flows downhill, downhill is a direction, and the shortest route down…