Missouri River Degradation

[moderne]

The Sun Tribune is reporting that the Army Corps of Engineers is seeking funding from local riverfront municipalities for a $6.5 million study of the wearing away of the river bottom.  The Corps states that the bottom of the river has lowered approximately 12 FEET in the past 18 MONTHS!  That seems like an incredible statistic and I think would threaten bridge structures.  At this rate we could soon have a canyon running through town.

[grovester]

http://www.chiefengineer.org/content/co ... t/3753.htm

Hopefully it's the 12 feet in 50 years this article quotes, otherwise we're in serious trouble!

[jdubwaldo]

Or 12 feet in 60 years as the original article cited states.... 

According to Ostrander, the bottom of the Missouri River has lowered approximately 12 feet in the past 60 years throughout the Kansas City area, which can lead to problems with bank stabilization around the river.

[aknowledgeableperson]

That problem was reported years ago and they are just now wanting to study it.

One solution that wasn't very popular - eliminate the barge traffic and return the river to a more natural state.

[FangKC]

It's called erosion people. I would imagine that years of channeling and straightening the river has contributed because it forces the water to move faster downstream.

Plus, all the runoff from storm sewers and manmade surfaces sends vast amounts of water into the streams and the river from surrounding areas where in the past that water was slowly absorbed into the earth.

What is their solution? To dump soil into the river bed? How much is that going to cost?

[warwickland]

That problem was reported years ago and they are just now wanting to study it.

One solution that wasn't very popular - eliminate the barge traffic and return the river to a more natural state.

The Missouri River never was as amenable to water traffic as the Mississippi. It would be pretty amazing to return the MO to a natural state, KC never was always much more friendly to the railroads, anyway. Denver seems to be doing just fine without a navigable waterway.

[KCKev]

Put in some turbines to generate power and slow the flow... How hard could that be?

Use the money from selling the power to get light rail started...

So easy a caveman can do it  :lol:

[Highlander]

It's called erosion people. I would imagine that years of channeling and straightening the river has contributed because it forces the water to move faster downstream.

Plus, all the runoff from storm sewers and manmade surfaces sends vast amounts of water into the streams and the river from surrounding areas where in the past that water was slowly absorbed into the earth.

What is their solution? To dump soil into the river bed? How much is that going to cost?

I do not see why this is considered a major problem.  The only possible result is that the Missouri's channel would narrow slightly, but there is not going to be any canyon.  It is impossible.  For a canyon to form, the elevation of the river and its valley downstream of Kansas City would have to drop signficantly to allow for downcutting.  Because that is not going to happen, the capability of the Missouri to erode its channel in the KC is severely limited.  The channel becomes slightly deeper and the rate of flow slightly slower.  Not really an issue. 

[aknowledgeableperson]

  The channel becomes slightly deeper and the rate of flow slightly slower.  Not really an issue. 

The issue is the damage done to items such as bridge piers that are in the water.

[DeadendLafayette]

The issue is the damage done to items such as bridge piers that are in the water.

I don't understand how the water affects the bridge piers. Don't they go all the way down to bedrock, which (hopefully) couldn't just be washed away like a regular bank?

[anniewarbucks]

I can't figure out why the Missouri River does not have sand bars like the Kansas and the Platte rivers. On a normal summer a person can walk accross portions of the Kansas. The Missouri river is faster flowing river granted but there should be some way to slow this river down to preserve the river bed. Here in Topeka they placed a concrete weir across the river to keep the water at a even height at the water intake for the city. This could be done to the Missouri at different locations to keep erosion at bay.

[Highlander]

I can't figure out why the Missouri River does not have sand bars like the Kansas and the Platte rivers. On a normal summer a person can walk accross portions of the Kansas. The Missouri river is faster flowing river granted but there should be some way to slow this river down to preserve the river bed. Here in Topeka they placed a concrete weir across the river to keep the water at a even height at the water intake for the city. This could be done to the Missouri at different locations to keep erosion at bay.

I think you answered your own question.   The current, even at non-flood stage, is fast enough to remove sand from the system.  The current is a consequent of the narrow and straight channel maintained to make river traffic possible.  We could indeed build small dams across the river to slow it's flow but that would require a series of locks for boats to pass upriver.

[aknowledgeableperson]

I don't understand how the water affects the bridge piers. Don't they go all the way down to bedrock, which (hopefully) couldn't just be washed away like a regular bank?

From the article posted by Grovester above:

When the river bed drops, it exposes more of the pylons holding up bridges. That decreases the support the foundation gets from being buried in the ground. Left untended, that can increase the risk for failures.

[IraGlacialis]

I can't figure out why the Missouri River does not have sand bars like the Kansas and the Platte rivers. On a normal summer a person can walk accross portions of the Kansas. The Missouri river is faster flowing river granted but there should be some way to slow this river down to preserve the river bed. Here in Topeka they placed a concrete weir across the river to keep the water at a even height at the water intake for the city. This could be done to the Missouri at different locations to keep erosion at bay.

You can find them on the Missouri, but they will only either be quite a ways upstream or past Jefferson City. Channelization straightens the river out and increases flow speed, which means that sediment stays suspended and that there is no shelter for it to settle down in.
A way to naturalize the river, yet still allow for traffic, could be to create a series of side canals to increase the surface area of the river, and to have some of those canals flow into rehabilitated wetland. Increased surface area slows the water down naturally, while the wetland would serve, on top of that, the purpose of filtering the water (the Missouri, even though it has improved a bit, is still extremely polluted) and creating shelter for wildlife.
Only issue, besides the cost, would be that you would be cutting into land.