River Bumps

[petehowell]

Was flying over the Upper Mississippi this morning and got a good look at something I had seen before. I called them river bumps. (Circled in red)

Here is the pic. They are too uniform not to be man made. Does anyone know their purpose? I'm thinking they help define the barge channel.

[lr172]

Not a civil engineer, but my first guess would be some mechanical abutment that is disrupting the bottom flow/current at the edges with the goal of forcing deposits to occur at the edges and forcing all of the bottom erosion to occur in the center of the river to avoid dredging activities. Dredging is expensive and on the mighty Miss, I would expect the army corp to take proactive steps to minimize dredging expenses and keep the shipping lane deep.

Larry

[petehowell]

Hey Larry,

That makes perfect sense to me. Hope you had a good Thanksgiving!

Originally Posted by lr172

Not a civil engineer, but my first guess would be some mechanical abutment that is disrupting the bottom flow/current at the edges with the goal of forcing deposits to occur at the edges and forcing all of the bottom erosion to occur in the center of the river to avoid dredging activities. Dredging is expensive and on the mighty Miss, I would expect the army corp to take proactive steps to minimize dredging expenses and keep the shipping lane deep.

Larry

[David Paule]

I don't see the photo....

Dave

[BillL]

What photo?

[NLPete]

Pete, I can't see the photo but are you looking at a wing dam? There are a bunch of them in the Mississippi. I watched a guy get pitched off the back end of a boat that hit one. The boat driver didn't know about the dangers of them (or what the buoys were for either). https://en.wikipedia.org/wiki/Wing_dam

[petehowell]

Hi Nathan,

Did not look like a wing dam. Hopefully the pic will show up for everyone - Google Photos can be fussy, but they usually show up.

Originally Posted by NLPete

Pete, I can't see the photo but are you looking at a wing dam? There are a bunch of them in the Mississippi. I watched a guy get pitched off the back end of a boat that hit one. The boat driver didn't know about the dangers of them (or what the buoys were for either). https://en.wikipedia.org/wiki/Wing_dam

[swjohnsey]

Yep, wing dams.

[petehowell]

Stan and Nathan,

Thank you!

I missed this in the Wiki "Many wing dams are often underwater and may be difficult to see, and can easily be struck by vessels."

Originally Posted by swjohnsey

Yep, wing dams.

[Desert Rat]

Those are definitely wing dams/dikes. the encourage the current to keep the shipping channel scrubbed deep enough that it minimizes dredging requirements.

I race Kayaks on the Missouri and every year somebody or other will poke a hole in a boat by hitting one of those just under the water. They can be either underwater of high and visible, depending on teh river level, which changes quite a bit more that you would think.