What are watersheds and why should they be protected? What could you do to protect watersheds?

I'm supposed to find sthe answer to this, but my textbook doesn't say anything about why it's useful to humans... the only thing that it tells me is that it's an area surrounded by high land and drained by a river and its tributaries; all runoff from withing the watershed leaves the watershed at the same exit. I've also looked online for information on how is it useful to humans and wildlife, but I haven't been very succesful with it...

1 answer

Read these sites carefully.

http://news.mongabay.com/2009/0319-hance_watersheds.html

http://www.nature.org/initiatives/freshwater/features/watershed.html

(Broken Link Removed)