Dredging a Shallow River

they just cut the channel out deep enough to clear the barges and ships.

the river might get narrower, but the shipping will have a clear path...

I'd imagine it would be in a specific channel -- diverting the existing water to that spot and making it deep enough for the barge.

Yeah, just found this:



http://www.fresnobee.com/2012/08/22/2961143/coast-guard-reopens-mississippi.html#storylink=cpy

-signed, grew up blocks from the Mississippi

Love your thinking gollum, the whole river would be lower but the effect would be spread out so the dredging would only make the river deeper ( more navigable) in the area of concern.

First the bottom of the Mississippi river below Memphis is below sea level. Dedging only lowers the bottom which is somewhat backfilled from the gulf--this is already being demonstrated as increased salinity in municipality potable water suppies is being encountered along the lower Mississippi.

Second--Eads Wiers (those dikes built perpendicular to the river banks) work by increasing channel flow to scour the channel bottom. If the river surface flow isn't there because of lower river surface elevation, channel scouring won't happen. IOW the mechanical scouring of the channel is necessary because the engineered scouring isn't happening.

Additional--keeping the Mississippi open is transportation mission critical. One barge is equivalent to 100 semi truckloads or 40 train carloads. Along the Ohio, Misissippi, Missouri, Tennessee an Kentucky Rivers barges is the cheapest method of bulk freight--bar none. Losing this transportation venue, even temporarily, can be economically significant.

Rap