You and a friend are planning on hiking separately and meeting at a lake neither of you have ever been to before. The map shows it to be a hilly area, with plenty of streams and trees.
You're sure you can find the lake, and walk around it if necessary, but visibility might be poor. Where should you arrange to meet to be sure of finding each other?
There is a simple solution to this problem, which outdoorsy types should be familiar with.
(In reply to
why? by gary)
hydraulics.
Think of it from the point of view where the lake is not yet full. As more water enters the lake, the water level will rise slowly until the point where it discovers an exit (the outflow). The water will then come into balance with water in=water out maintaining that approximate water level(it will fluctuate somewhat with weather and seasonal changes). While it is true that the water level at one end of a lake may be slightly different than the other, I will hazard to say that this difference is very small (maybe a foot?), not large enough to allow the lake to find a second exit point. In the rare cases where this does happen, in the long run (and remember that most water bodies have been around for a VERY long time), differential erosion will tend to eliminate the egress points until only one remains.
So it is possible to have more than one outflow, but in natural settings this would be extrememly rare. Having seen the map (as the problem states) you could eliminate even this small probability.
re: why?
