>>27650398Anon, the river would not fill up with one ton of water.
Assuming five rivers each can carry one ton of water, and they all merge into each other, then that resulting river would be pumping out five tons of water into the lake as well, and the resulting river would be capable of producing much larger forces than any individual river could've produced flowing into the lake alone.
If we take your analogy, then five separate rivers flowing into the lake would create five moderately powerful flows of water and fill the lake to five tons, but after combining, the one lake would shoot five tons of water into the lake with massive force.
Unless you're saying the five rivers that form into one are weaker than the five separate rivers, but then that analogy wouldn't make any sense at all.