Nobody knows nuthin

Barry. It's a thing that exists now.

Tropical Storm Barry's potential impacts are coming into sharper focus as the National Weather Service said Thursday that it now expects total rain accumulations of 10-20 inches over a swath of southeast Louisiana, with isolated maximum amounts of 25 inches through the weekend.

The pockets of heaviest rain, the National Weather Service predicts, would occur in areas around Baton Rouge and south to the coast.

That's pretty good news for New Orleans, relatively speaking.  But it's a few days away still so we'll see. 

Already by yesterday we had arrived at the point where everyone asks the mayor if or when she is going to call for evacuations. Sometimes I think they're almost daring her to do it. But, as LaToya pointed out, you're always free to leave at any point if you really want to go. Nobody is going to stop you.

Though she declared a state of emergency, Cantrell said it was too soon to say Wednesday whether the city would call a voluntary or mandatory evacuation ahead of the storm’s arrival.

“We will make those calls once we feel they need to be made,” Cantrell said. “As it relates to residents leaving, people can make up their own mind based on conditions now. That’s something that they can always do.”

Today she added to that saying "We look (for) a Category 3" before calling for evacuations. That sounds informally correct. But also it sounds new in the sense that there is or ever was a hard and fast policy. Often it seems like LaToya is making it up as she goes along.  There are good and bad things about that.

In a sense, there is a "voluntary" evacuation on right now. Really, all evacuations are voluntary. Even a "mandatory" evacuation order doesn't mean police are going door to door and pulling people out of their homes.  They don't have time for that during an emergency. The critical decision from the mayor's point of view is whether or not to kick the city assisted evacuation procedures into action. That involves mobilizing buses and police and volunteers and staging venues and all sorts of stuff. It's not a decision to pull the trigger on unless you think it's definitely going to be necessary.

Meanwhile from an individual's perspective, there are all sorts of factors that go into deciding whether or not to evacuate. If you have a place to go and the means to get there then you might consider it.  But evacuating may be more of a risk for some than staying put.  Not everyone is mobile enough to just up and go at a moment's notice. Not everyone can afford to miss a few days of work. Not everyone's boss or landlord is going to be cooperative. Then there is the fact that evacuating is expensive as hell. Not everyone has money put away for emergencies. And there are other costs to leaving beyond just the money spent on the act. Sometimes after a storm has passed, the city might decide to drag its feet on allowing people to come home. Evacuees might find themselves stuck out on the road longer than they had planned with compounding consequences for their lives when or if they ever get back. So, by all means go if you can or want to. But it's hardly ever the right decision for everybody. "Mandatory" evacuations should be called sparingly if at all.

Also it sucks to be stuck in some shelter hundreds of miles away when you could be at home managing the situation.  Maybe you can mitigate damage by being on hand to patch a broken window or move some of your belongings out of harms way if the water comes up. Or what if it turns out your car wasn't parked in the safest spot?  Maybe you can get it moved before the water gets high enough to damage the engine... even if you don't quite make it in time to keep it out of the cab. Still, at least you can get to work cleaning it up right away. Can't do that from some gym floor in Alabama or whatever.



Anyway we're probably not going to call any sort of evacuation for Orleans Parish. It's not usually something that happens when a yet-to-be-organized storm is still expected to become a category one hurricane at worst.  The main reason it's being taken a little bit more seriously today is because people are freaked out about this river situation.

Storm surge accompanying potential Category 1 Hurricane Barry may cause overtopping Saturday of much of the Mississippi river levee in the Lower 9th Ward, Algiers and St. Bernard Parish, according to Army Corps of Engineers levee data.

The National Weather Service's Lower Mississippi River Forecast Center in Slidell expects the surge will add between 3 and 5 feet to the unusually high river in New Orleans and locations to the south, reaching as high as 20 feet at the Carrollton Gauge in New Orleans.

Basically what's happening is, as the storm surge piles in from the Gulf, the river can't discharge at its mouth as fast as it ordinarily would which causes the water level to rise a bit more in its channel. The predicted spike is only expected to last about a day. And, in most spots, they're saying it won't go above the height at which the levees are designed to hold it.

Maybe.

But a map of levee heights in the New Orleans area that's part of the Corps' National Levee Database shows that the top of large segments of river levees along the Lower 9th Ward in New Orleans and St. Bernard Parish on the east bank, and some locations in Algiers on the West Bank, were between 18 and 19.99 feet.

Thus, a 20-foot river height could cause overtopping at those locations, something that has never happened in New Orleans' modern history, and only rarely in St. Bernard.

So there is some discussion as to how serious this actually is.  To begin with "overtopping" is not necessarily a disaster unless it becomes serious enough to scour out and undermine the levee itself. At that point, well, look out.  But the Corps says, #actually that list of levee heights may not be the list that counts. 

Late Wednesday, a spokesman for the Corps,  which oversees construction and repair of the river levees,  said officials in its New Orleans District office discounted the data in the agency's database.

"They show the levee elevations for the 9th Ward between 20 and 21 feet," said spokesman Ricky Boyett. "Our modeling does not show overtopping of the levees in the 9th."

According to this they're still worried about overtopping becoming an issue in Violet and in several spots in Plaquemines but the supposedly vulnerable places in New Orleans probably won't be as bad as the maps suggest. There are some confusing reasons for this. But it sounds like the Corps is saying it depends on how you measure water. 

And Boyett said there's a good chance that the way the water in the river is measured, compared to the height of levees, could provide about 8/10 of a foot of additional protection.

The river gauge on which the water levels are measured uses a 1929 datum measurement to determine its height, while the corps uses 1988 datum for levees, resulting in the height difference, he said.

I think what they're saying is that in 1988 they found out the water wasn't as wet as it used to be so it's okay for it to go higher now.   McBride actually explains it here reminding us that the "datums" discrepancy was a key factor in the design flaws that led to the flooding of New Orleans after Katrina.

Literally finding #1 in the Corps' own wide-ranging "IPET" investigation of their own failures which caused the levee failures after Katrina passed New Orleans was that the Corps' use of different bases, or "datums," for measuring heights was a serious contributor to the failures. Doing so allowed shorter structures to be built without anyone realizing it until it was too late. Some levees or floodwalls ended up multiple feet shorter than intended.

So maybe that's not very reassuring.  But this might be. 

Forecasters have lowered by a foot their predictions for how high the Mississippi River will get once Tropical Storm Barry's comes ashore this weekend, giving the New Orleans-area levees a bit more breathing room.

The Mississippi is now expected top out "near" 19 feet above sea level at the Carrollton Gauge in New Orleans on Saturday due to the storm surge from Barry, which is expected to come ashore as a hurricane, according to a National Weather Service alert sent out Thursday morning. Forecasters had previously predicted the river would reach 20 feet during the storm, potentially matching or exceeding the height of the Mississippi River levees.

Of course 20 is still "near" 19. That's good or bad depending on your particular datum orientation. And, of course, the surge forecast can change again or be entirely wrong anyway. At the very least this shows us that even the most precise measurements and models employed by the professionals in charge of managing critical infrastructure still boil down to guesswork.  In other words, nobody knows nuthin.' But we already knew that.

Case in point, here is Alli endeavoring to "untangle the knot" of everything we know and don't know about what caused yesterday's street flooding. It's a lot of things. From the basic philosophy underpinning our water management strategy, to the design and engineering of its components, to the maintenance of the infrastructure, to the politics that chooses what gets emphasized, there are so many unknown knowns.  We would like to think the trick is to at least separate out the bullshit. But how do we even start?

Untangling this knot will take time, but it has to start with everyone telling the truth. After an event like today, the public outcry for SWBNO to fix the pumps will continue. But I think it’s almost more important for them to be clear about what they do know and don’t know about the system that we have, rather than throw more money at repairs in the short term. At least then we can start on a path of actual public information about risk, and what it would take to change our approach to water management. Right now, we aren’t even sure what’s broken, besides “everything.”

What's actually broken? Nobody knows!  So what do we do now? There are all sorts of ideas people have about who they'd like to see benefit and who they'd like to see suffer in the meantime. The politics is going to happen even whether we're ready to say what we know or not.

Is it becoming too dangerous or "unsustainable" to live in South Louisiana? Or are there sincere actions we could take to save what's left before it's too late?  Nobody knows. But oil and gas and shipping still want their infrastructure protected. The tourism cabal still wants to host parties in New Orleans. It's fine with them if everyone else is a "climate refugee"

This, again, is why I don't expect we're ever going to fix these things.  Climate change isn't a "game changing" existential problem politically speaking. Politics is always about who wins and who loses and the interests of concentrated wealth run contrary to the concerns of the "99 percent." Guess who usually wins.  In New Orleans, we might not know precisely what's "broken" about our storm management infrastructure. But we still have to act based on our most honest appraisal of the guesswork we have now, or cede every decision to actors who have none of our interests in mind. Even in full view of this the best we can hope to do is to watch the shitty politicians  muddle on through a slog of concessions and compromises.  Unfortunately muddling through is going to have disastrous consequences for the great majority of people while the rich continue to make themselves richer.  But that's what always happens.