Sue Uglow, age 13, of Oconomowoc, Wis., for her question:
HOW ARE LOCKS USED ON RIVERS AND CANALS?
World's longest canal is the 684 mile long Volga ¬Baltic Canal in Russia which includes seven locks. Second longest is the 524 mile long New York State Barge Canal which has more locks than any other canal in the world: A whopping 57. The important Suez Canal in Egypt, although 101 miles in length, doesn't have a single lock because the water is at the same level at both ends of the channel.
A canal is a man made waterway. Some are natural waterways, with dirt bottoms and sides, while others have bottoms and sides made of stone or concrete.
Locks, or special chambers, are used when a waterway leads from one body of water that is higher in altitude than the next body of water.
A canal lock is actually a concrete or stone chamber with watertight gates at either end. Although they vary greatly in size, most locks are from 400 to 1,000 feet long and from 66 to 110 feet wide.
Canal and river locks make it possible for ships to move easily from one water level to another. Lake Erie, for example, is 325 feet higher than Lake Ontario. A series of eight locks in the Welland Canal connects the two lakes and allows ships to move from one lake to the other.
When a ship moves into a canal lock, the gate closes behind it. Drains in the chamber are opened and water is pumped out until the water in the lock is at the same level as that in the next lock. The gates to the next lock are then opened, and the ship goes through. This process is repeated as the ship moves through all of the locks.
To move a ship from a lower level to a higher one, water is pumped into the lock until it is at the same level as the higher water in the next lock.
Next to the lock less Suez Canal, which is the busiest interoceanic canal in the world, the Panama Canal is probably the world's most important waterway. It has three sets of locks, each of which is 1,000 feet long, 110 feet wide and 70 feet deep. The waterway is 50.7 miles long. Completed in 1914 at a cost of about $380 million, more than 14,000 ships go through Panama Canal each year.
In 1959 the improved St. Lawrence Seaway opened to traffic as a joint Canadian and United States project. Ocean going vessels are now able to sail from the Atlantic to ports on the Great Lakes in the Midwest. This great waterway, which includes seven locks, extends almost 200 miles from Montreal to Lake Ontario. The waterway has a minimum depth of 27 feet.