Quote Originally Posted by Gamerprinter View Post
OK, Juggernaut, have some REP for that bit science on rivers!

My curious question now regards the Yucatan Peninsula, and the Island of Cozomel. I've been to Cancun, Mexico, on vacation a few years ago, having recently (at the time) learning about the propensity of underwater rivers in southern Mexico. The island of Cozomel (largest island off Mexican coast, very near Cancun.

Most of the Yucatan is extremely flat, but there are almost no surface rivers there. Sinkholes everywhere. Underground rivers everywhere.

I visited a "park" that contained a sinkhole right near the coast, about a half mile away from the sea. Fresh water rose from the sinkhole and formed a short surface river called a "Ria" that reached the sea.

Cozomel is really not that big, yet underground rivers course meandering around the reaching the sea.about 5 meters under the surface.

I've always wondered about the science regarding that... Can anyone answer, Juggie or Waldronate?? It seems almost bizzare.

GP
GP> Thinking about this one... trying to nut the sucker out and I keep coming back to some stuff that is hard to explain but easy to demonstrate.

Everything has a property called "surface energy" (it's basically the energy required to make surface area)...

If you drop a liquid on a surface (i.e. glass, the kitchen bench, a sink) it reshapes itself to minimise its surface (because more surface = more energy) and the universe likes to minimise energy.

Why does this matter?
Experiment: Get a glass of water, stick a dishcloth in it, drape the dishcloth over the edge of the glass and into the sink. Do the same with another glass but use a NORMAL cloth (any old boring bit of tight-weave fabric)

Expected results: Water climbs the cloth, over the edge of the glass and down the sink. (Note: if you use hot water, it should do it faster). The dishcloth glass should be more empty than the "normal cloth" after say 1 hour.

How the cheese does this relate to sinkholes and the Yucatan?
The ocean is your "sink". The water source is your glass. The two cloths represent the different kinds of land.

Water likes touching water, but it also hates having lots of surface. In the tight-weave cloth you reduce the surface (by making it touch the cloth) BUT more water is touching cloth which it doesn't like much. There is also no nice smooth "water highway" through the cloth. Any water has to move around in a lot of directions to get around the threads.

In the dishcloth, there are lots of nice holes and spaces. Holes = water touching water which is good. Cloth = less surface which is good. Loose weave = clear paths to the other end of the cloth. Hence the water should move faster.

SO back to the Yucatan. Given the options: make a river versus "flow through this swiss-cheese rock stuff" the one that has the least energy involved is the "swiss-cheese rock" AND because there is less energy spent on surfaces, more energy can be spent on moving and hence it is a faster path making sure it meets the requirements of the river police.