Wabash River Meanderings

When I was studying the former Illinois Central RR bridge over the Wabash River near Grayville, IL, I noticed in a satellite image that the state line between Illinois and Indiana no longer aligns with the river.



And when I did a further analysis of the satellite view of the Wabash River for the Illinois bridges posting, I noticed that there were other meanderings on the Wabash River. This taught me that meanderings don't happen on just the lower Mississippi and that they happen on a human time scale instead of a geologic time scale. In fact, the above oxbow lake was made by the 1985 flood.

And according to a flood marker down by the boat launch in Grayville, IL, the 1985 flood was not even a big one. The plaque near the top reads "WABASH RIVER CREST   APRIL 1ST 1913". The plaque added near the bottom reads "RIVER  CREST 2002."

I marked a map to get a feel for the density and location of the meanderings. The "gray" marker that is the fifth from the bottom is the Grayville cutoff. All of the markers are cutoffs except the second and third from the top. The second one shows a meandering that is just starting. And the third one down shows a meandering that is closing off. Zooming in on the marker that is north of Vincennes, you see Grays Pond. That looks like an oxbow lake that formed long before the state line was drawn. I also did a quick look down the Mississippi River and found an interesting segment of three cutoffs in close proximity. I wonder if the Army Corps of Engineering helped mother nature make these cutoffs to shorten the barge channel. You can also see how cutoffs make new curves and the inside of the curves form new sandbars.

If you zoom in on the top map to the part just above the I-64 bridge, you can see that the east side used to be on the outside of a very gentle curve, but now it is on the inside of a rather sharp curve. This has moved the fast water flow to the west side of the river and increased the speed because the new sand bar has reduced the river width. This new flow is destroying the I-64 bridge.

And that sandbar has filled the old shipping channel. That is why we now have a swing span over land.

Bridge Hunters: Richard Dale in October 2010

Update, Nov 2014:

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