Complex Numbers

Muddy Talks

I'm participating in "Journalistic Intentions"  [18+] again this month, so some of my entries will be prompts from that activity.

This is one of them—as usual, selected at random.

Locks, dams, and the future of the Mississippi  

When I was in Minneapolis in the summer of 2021, I got to see some of these locks and dams up close. I wrote, briefly, about it at the time: "Dam It" 

So apparently, based on the link above, there's talk about removing some of them. Not the ones I toured, but downstream from there.

You might think that, being a civil engineer whose whole thing was hydrology, I'd have an opinion on it. After all, I have opinions on plenty of things that I know far less about. But you'd be wrong. Well... I do actually have an opinion, which is "they should do what's expected to have the best overall outcome." Which is why we have people do studies for this sort of thing.

If I thought about it long enough, I'd probably come to the conclusion that this should probably be my opinion on everything else, too. But no, then life would be no fun, and worse, I'd have nothing to blog about.

Besides, rivers are complicated. They build dams for reasons: flood control, erosion prevention, power, recreational purposes; usually some combination of these things. There's always a trade-off too, like when the dam blocks fish spawning or whatever, or the resulting lake drowns a community.

Left to its own devices, a river will shift over time. Not just geological time, but often in one human lifetime. You can see the effects if you look closely at a map of the rest of the Mississippi: horseshoe bends where the river once flowed, and down the center of which a state line was surveyed, have gotten cut off, leaving, for example, a bit of Tennessee on the Arkansas side of where the river is now. Several bits, actually. Some of that might have been due to Army Corps projects, but probably there was also some non-human-caused shifting over the years. If you wanna see, look up Memphis on Google Maps and then scroll north.

And I'm not saying this is bad, or good; it just is. We modify rivers for our own purposes, and for a long time we didn't think much about the consequences. Now that they're modified, though, there are consequences to unmodifying them, as well.

Even further downstream, in Louisiana, the primary Mississippi discharge has been trying to shift over to the Atchafalaya river (no, I can't pronounce it, either). If it weren't for levees and locks and whatnot—engineering projects—it probably would have switched channels by now. From what I understand, it used to switch back and forth every thousand or two years. As one channel silts up, water flows to the other, and vice-versa.

This, of course, would leave New Orleans dry (if not high), so there are economic reasons not to allow it. But there are probably good solid ecological reasons to do so. But we're a part of the ecology, too, part of nature, and we have to make decisions based on incomplete information.

I'm just glad it's not my job.