Can anybody answer a question about locks and dams?

Question

My mother always said to stay away from dams because of the suction. I've always wondered about that, so I've tried to find information. The only things I've managed to gather (besides some beautiful photos and scary footage of dams collapsing) is that rolling dams and low-head dams are dangerous because of the hydraulics they create. But looking at the design of other dams, it doesn't look (at least) like they would be dangerous. Are they? If so why? Also, how exactly do locks work and why are they considered dangerous?

Answer 1

most large dams have spillways either at the top or by gates located near the bottom of the dam.  These are used to adjust the level of the water behind the dam and to insure that there is water at a proper level on the downstream side of the dam.  (many small dams do not have the underwater gates but have small fixed spillways)  If you should happen to be swimming near the dam when the underwater gate opens or even if it is already open the rushing water might pull you down and into the water flow...most gates have some type of grill to prevent large objects from going through so you might be held against the grill and not be able to swim away...or if there is not a grill you could be carried through the spillway and fall into the river below.  Best to stay away from a dam.

Answer 2

Your mother is correct, stay away from them.

I don't want to write a hundred pages on how they work but here is a pretty good website for you to read and learn more of what you are asking.  Good question.

http://www.wisegeek.com/how-do-dams-work...

Answer 3

Locks function by raising and lowering water to raise or lower a ship.  A ship enters an area with a gate in front and one in the rear.  The gate in front remains closed and the gate in the rear is closed.  Water is pumped into the area and the ship is raised.  Once the the area is filled the front gate is opened and the ship sail on.  Of course to lower the ship you would with draw the water.  They are not dangerous to ships.