Tragedy that has to happen to be believable?

[MossRoad]

Given speed of the inundating water [rather than total river flow] there are those that could figure it out almost off the top of their head. Not me. Off the top of my head tho, and from deep enuf in to know it for a fact, the pressures seen are much lower - in a range below 10psi. -- Its forces [pressure times area] that are huge. A force of a thousand or more pounds can easily be applied to a person.
larry

Everyone has to recognize a few danger spots in a river. Places between rocks, logs, dams, bridge pilings, etc... where currents suddenly increase.

In our man made whitewater course, we had a spot that was about 20' across and the current was flowing at 4MPH, or about 5.4 feet per second. The water was 4' deep. The pressure exerted against your body is about 300 pounds per square foot. You cannot stand up in that current. We put in a stop log across 1/2 of the channel, narrowing the channel to 10' wide. Now the same amount of water has to move through 1/2 the space. The current instantly increases to 8 mph. You would think the force of the water would double at that point. But it doesn't. It goes up by a factor of 4. So the force against your body is now over 1200 pounds per square foot. If you are pinned against a rock or log with that much water pushing against your body, well, its deep doo-doo time.

 

[jimmyj]

You engineer guys crack me up. Bless you all for knowing the implications of changing water flow. LOL.....:laughing:

 

[Sigarms]

You engineer guys crack me up. Bless you all for knowing the implications of changing water flow. LOL.....:laughing:

Simple.

Go up to the Ottawa river and look at Phils hole running at 500 CFS. Take a look at the same hole on the same river running over 5,000 cfs. You'll see the implications

That said, more waterflow does not always mean increased danger, and actually it could be more dangerous at lower water levels.

 

[MossRoad]

You engineer guys crack me up. Bless you all for knowing the implications of changing water flow. LOL.....:laughing:

I'm not an engineer. Math hurts my head! :laughing:

But being a lifeguard on a whitewater course, they teach you that stuff so you know what you're up against, what to avoid, and how to attempt to get out if you mess up.