Subject: why don't rivers just drain into the ground like water poured on the ground

when I turn on a hose and leave it on the ground the water soaks into the 
ground. If a deep puddle forms after a rain the water in the puddle dissappears 
at a rate faster than it evaporates.  Why doesn't the water in a river just 
sink into the soil like water does everywhere else excect lakes and oceans?

Re: why don't rivers just drain into the ground like water poured on the ground