What are the world's fastest and slowest flowing rivers?

I don't know who measures it, but when I studied geomorphology back in the Dark Ages, we used to measure relative energy of a river, but you'd have to track flow, elevation change, relative volumes, etc over the entire course of the river. It has probably been done, but darned if I know where the info is. Rational guesstimating would lead one to conclude that the fastest river would be a relatively short one located somewhere in the mountains.

gmack, you might try to look under geomorphology if you're really looking for the answer. I no longer have my old texts, but there were some pretty complicated mathematical formulae for figuring out the relative energy of a stream. Of course, as mentioned earlier, it would vary depending upon time of year, sites measured, etc. For simply measuring velocity of flow, I would imagine that one would come up with site-specific measurements, as in, "the fastest recorded flow was on such and such a date at such and such a place", etc.

The Atrato in south America is claimed by more than one site to be the world's fastest and empties 4900 cubic metres of water per second. The Amazon and Terek rivers (the later is in the Caucasus) also have claims for them on other sites. A site about the Sutlej river in India says it is the second fastest in the world.

The fastest river in the USA, according to many sites, is the Merced River in Yosemite National Park in California. The fastest in the UK is the Spey River in Scotland (flow rate reaches 16 m/s).

Many sites agree that the Everglades are flowing slightly from north to south so the swamp can be called the "slowest river in the world". Mind you, I suppose the answer to that one depends on whether we count glacial rivers such as the following:

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