DuckSouth.com

Because it is like dumping a thimble into a bathtub... The Mississippi river drainage south of Vicksburg is massive...

I think I understand your point, but if there was/is all this additional drainage capacity in the MS River further south, then why didn’t that prevent the areas near Greenwood from flooding?

My very simple logic ( which may be wrong) is that the MS River was backed up by above normal local rainfall, as well as a lot of runoff from flooding and melting snow in the northern MS River states, which caused the Yazoo River to back up, which in turn caused the Tallahatchie and Yalobusha Rivers to back up, resulting in the flooding I witnessed and experienced first hand.

So, all the water that flooded the south Delta was just a relative “thimble full” compared to the unused drainage capacity?

I’m not arguing, but trying to understand.

Also regarding pumps........
Ive been designing them for years and the general rule is pumping systems are design to only address around 10%-15% of what a gravity system can handle.
Example:
Pump station in Gwood by the USACE office.
3 pumps at 30,000 gpm (90,000 gpm -200 cubic feet per second)
Gravity flow (double 10 ft x 10 ft box culvert with 1 ft of head on the top of box) 1500 cfs

The capacity of the MS River below Vicksburg is effectively infinite compared to the capacity of the proposed pumps. Thus, the pumps would impact MS River levels negligibly. In turn, the levels of the Yazoo River would be impacted negligibly, being open to the MS River. Cascading that effect upstream, you get impacts that are .... negligible.

If the pumps were discharging into a system with finite capacity, the story might be different.

Imagine your backyard (Gwood) floods due to a quick thunderstorm. You have a catch basin in the back and French drains (Yazoo) take it out to the curb (MS River) in front of your house. There’s another catch basin (Steele Bayou) close to the road, that catches some water in the front yard. If your dog goes and pisses (pumps) in that drain in the front yard, it doesn’t do anything to the backyard. This ain’t a perfect analogy but it serves the purpose.

anytime there's a pissing dog thrown in us MS boys can understand it better

So, in summary, adding the additional water that would be pumped into the Yazoo River (the big orange funnel) will affect those of us further upstream no more than a thimble full in a bathtub or a squirt of dog piss.

Thanks

I seem to recall hearing someone from the Corps saying that at one point they actually recorded something like 45,000 cfs flowing "upstream" in the Yazoo.

I was gonna say, the flow may have been backward at that time.