Explaining the elephant in the room, or rather, the river

It’s May and the river is up. My friend Greg Trainor is a river runner and knows a lot about water. I’m not exactly sure what a river runner is. Personally I can’t even walk on water on a still, small pond, but he apparently can run on the river.

Anyway, when we went to dinner the other night he told me that there was 10,000 cubic feet of water flowing in the Colorado River that day per second. They expect there to be as much as 35,000 feet per second flowing at the river’s crest. He wondered how many elephants that would be equivalent to in weight.

I don’t know too much about elephants, so I looked up what a cubic foot of water was. One cubic foot of water per second is 7.48 gallons, and a gallon weighs about 8 pounds. A 5-gallon bucket of water would weigh 40 pounds. I happen to know that a 5-pound bucket of honey weighs about 60 pounds, so I guess honey is thicker than water. But I have no idea how much a 5-pound bucket of blood would weigh, so I can’t verify that blood is thicker than water.

Anyway, 8 pounds times 7.48 gallons of water would be 59.84 pounds of water in one cubic foot per second. So, 10,000 cubic feet of water passing by a given point at any given second would weigh 598,400 lbs.

According to the Mozilla Firefox search engine, the African bush elephant weighs up to 16,500 pounds. (I think I’ll round it off at just 16,000, knowing how mammalogists always exaggerate.) If we divide 598,400 lbs. by 16,000 we get 37.4 standard elephants worth of water that pass a given point every second.

That’s impressive! I think if you were running on the river, you would definitely want to stay on top because if you were on the bottom things could get pretty heavy. Granted, the weight would be spread out over the surface of the river bed. So if you were to go under the water, it would be better to do it where the river is wide. That would provide an increased surface area for the weight to rest on. Greg explained to me that, unfortunately, that is seldom where people go under.

There is another problem also. These calculations are just the weight of elephants on top of you at one undefined point for one second. I mean there would be 37.4 more elephants on top of you in just another second. I believe that could easily be called a stampede!

But how big is a point? (I was about to ask, “What is the point?” but decided against it.) Suppose you were to get in front of all the water coming downstream. (I really don’t see how you could get behind it very well, can you?) You would then have the weight of all the water upstream pushing you downstream.

Let’s suppose a point is 6 feet long. That’s how tall I am. You would have the first 37.4 elephants pushing down on you. Behind that there would be another 37.4 elephants pushing you downstream. Behind that would be another 37.4 elephants, and so on upstream. In just 100 yards you would have the equivalent of 623 elephants (or 9,973,333 pounds) pushing you downstream.

I can see right away, even if my assumptions are a little off, that walking on the water isn’t going to do anyone much good. If you are going to do anything, you had better run on that river, and run hard.  I guess that’s why they call them river runners.

I want to thank Greg Trainor for his help in writing this article. I couldn’t have done it without him. In fact, I would never have thought of such a dumb question by myself.

Do you think river runners are a little strange?

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Gary McCallister is professor of biology at Mesa State College.


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