Canals. Why don't they flood?

[mindblock]

Seems a really stupid thing to ask, but why is it that canals don't flood?
Is there a run off e.g. like on your sink at home?

[vehelpfulguy]

Yes, canals have a run off. You often see them at the side of locks so if the water level gets too high they bypass the lock doors and run down to the next level.

Canals also have run offs to rivers or streams. Canals often run near rivers and streams, and again they have a run off that takes water into the river or stream.

Here is a picture of one near a lock.

http://www.luphen.org.uk/images/2005/2005-06/2 005-06-07-130351.jpg

[almcd007]

They are also a body of water rather than a running river being fed by streams and drainage off land etc. A river fills up the more it's fed, a canal isn't fed like a river.