Epic High Five posted:

Luneshot posted:

Here's a fun study for y'all: what will major cities feel like in 2050?
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217592#abstract0

Appendix S2 is a spreadsheet of every city and the three closest analog 'future' cities.

Luneshot posted:

Here's a fun study for y'all: what will major cities feel like in 2050?
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217592#abstract0

Appendix S2 is a spreadsheet of every city and the three closest analog 'future' cities.

mastershakeman posted:

I bet it will if they blow the dams, that NASA site says that the atchafalaya is 20 feet lower and water prefers to go there. They can probably only open the gates so much right now , I'm assuming they're at max

quote:

With storm surge from Hurricane Barry forecast to raise the Mississippi River to dangerous heights on Saturday, some observers have pointedly questioned why the Army Corps of Engineers did not try to reduce water heights weeks ago by opening the Morganza Floodway above Baton Rouge.

When fully opened, the Morganza spillway structure is designed to sluice up to 600,000 cubic feet per second of water through a floodway that flows west into the Atchafalaya River Basin and then to the Gulf of Mexico through Morgan City.



But operating that floodgate to attempt to reduce water levels in New Orleans in anticipation of surge rises caused by a tropical weather system would pose a real threat of transferring the risk faced by one community to another, said a senior Corps official.

“Literally, physically, it can be done. We all know that,” said Mark Wingate, deputy district engineer for the Corps New Orleans District office. “But we also know that the Atchafalaya River Basin is already in flood, that Morgan City is also in flood.

“Do you want to take more water into Morgan City? Into the Atchafalaya Basin and put them at greater risk to benefit someone downstream on the Mississippi just because a storm might go to that area?” Wingate said.

“And now we know that the major effects of this storm are not going to that area,” meaning New Orleans, Wingate said. “It would have been a poor decision that now would actually have caused worse effects for those who are going to be the most affected.”

That’s because Barry is now forecast to move onshore near Morgan City early Saturday as a hurricane, which will push storm surge into the Atchafalaya Basin, where the Morganza Floodway water would also have been headed.

In typical years, the Mississippi crests during spring, meaning a high river typically doesn't coincide with a tropical storm system that can push dangerous surge up the river.

But Wingate said opening the Morganza earlier this year as a strategy to prevent high water issues in New Orleans during hurricane season also was an unacceptable solution. It would have immediately increased flood threats to Morgan City and communities in the Atchafalaya Basin in response to what was at the time a theoretical hazard to New Orleans, he said.

“We put 30 percent of the Mississippi River into the Atchafalaya every day, and as a result, Morgan City and other communities in the floodway have seen flooding threats for much of this year," he said. "I can’t make a recommendation to put more water into communities already in flood, to transfer that risk to them because it potentially might or might not help New Orleans."

A survey by researchers at the LSU AgCenter earlier this year showed about 18,000 acres of crops and pasture would be impacted by the Morganza opening. In 2011, the last time the floodway was opened, about 90,000 acres of crops and pastures were directly impacted.

Corps officials point out that it also takes about 7 days to notify residents and businesses in the Morganza Floodway, and to reduce the threat to wildlife, before the floodway structure can be opened. It then three days to open the floodway’s gate, and another day or two for the effects of the reduced water level to reach New Orleans.

The system that created Hurricane Barry hadn’t formed 10 days ago; by the time it had, the Morganza was not an option, they said. However, had it been open already, it's unclear whether they would have had enough time to close it to reduce the flooding risks in Morgan City posed by the combination of Barry's storm surge and the high water from the floodway.

Morganza is normally opened when there’s a danger that water flow measured at the Carrollton Gauge in New Orleans can’t be held below 1.25 million cubic feet per second by the opening of the Bonnet Carre Spillway just upriver of the city, and the flow of water past Morganza has reached 1.5 million cfs and is expected to stay at that rate or higher for 10 days.

Corps officials twice this year announced that Morganza would be opened, but then cancelled the openings when water levels in the Mississippi dropped below those thresholds.

The Bonnet Carre Spillway, which diverts water into Lake Pontchartrain, has been opened twice this year, for a near record 108 days. On Friday, 168 of the spillway’s 360 bays were open, transferring 112,000 cubic feet of water per second into the lake.

The official “standing instructions” for Morganza were most recently adjusted in 2014 to deal with potential high water issues that could damage the structure when the river flow at the structure reached the 1.5 million cfs trigger.

The Corps has an engineering study underway aimed at determining risks facing the Old River Control Structure stemming from recent deposition of sediment in areas north and south of that structure, which may include a larger review of how the Mississippi and Atchafalaya water flow is controlled.

But some scientists suggest the Barry scenario provides an opportunity to review other issues involved in using both the Bonnet Carre and Morganza structures to handle flooding.

Congress has traditionally mandated that the Old River Control Structure, upriver of the Morganza Floodway, capture 30 percent of the Mississippi’s flow, with the other 70 percent flowing down past Baton Rouge and New Orleans. That split dates back to the aftermath of the 1927 Mississippi River flood and was reinforced after the 1973 flood, which threatened to break through the control structure.

Without the control structure, scientists say, the majority of the Mississippi’s water would choose the shortest course to the Gulf of Mexico, which is the Atchafalaya basin. That would dramatically affect the lower Mississippi’s use as a world-class port.

But what’s carried downstream by the Mississippi – sediment and nutrients from fertilizer applied to Midwest farms – also might need studying, said Robert Twilley, director of Louisiana Sea Grant at Louisiana State University.

The nutrients have especially become a focus this year. Freshwater from the Bonnet Carre Spillway and numerous other streams and bayous running into Lake Pontchartrain and then into the Mississippi Sound have triggered the growth of harmful algae blooms, which in turn have created hazardous cyanobacteria and prompted widespread beach closings.

Twilley argues that a better timing of releases of high Mississippi River water, taking into account water temperatures, could help reduce the nutrient effects. If water is moved through the Atchafalaya basin, he argues, the nutrients could be better taken up by wetland growth, avoiding algae blooms.

But the split of water between the two basins must also take into account the needs of the state for quality sediment to rebuild wetlands along the lower Mississippi through diversions, and the problem that sediment may pose by filling in shallower areas in the Atchafalaya basin.

Twilley said one alternative also could use increased flow through diversions into the Maurepas Swamp, or to locations west of the river in the upper Barataria Basin.

“When the flow is between 700,000 and 1 million cubic feet per second, when it’s not a safety concern, but has a high sediment load, that’s a discussion we should probably have, where best to put that water and sediment,” Twilley said.

Part of that change could be tweaks in the flow through the Old River Control Structure that might require diverting from the strict 70-30 split, said Alex Kolker, a researcher with the Louisiana Universities Marine Consortium.

“But it would not cost a lot to change the distribution that way,” he said. “Science is a lot cheaper than concrete and steel.”

Wikipedia on Morgan City posted:

As of the census of 2000, there were 12,703 people, 5,037 households, and 3,394 families residing in the city. The population density was 2,166.5 people per square mile (837.0/km²). There were 5,627 housing units at an average density of 959.7 per square mile (370.8/km²). The racial makeup of the city was 71.28% White, 23.90% African American, 0.91% American Indian (U.S. Census), 1.02% Asian, 0.01% Pacific Islander, 1.18% from other races, and 1.69% from two or more races. Hispanic of any race were 3.37% of the population.

Sheng-Ji Yang posted:

seems to be rising slightly slower than expected. they had predicte 17ft at 1pm, at 16.92

Sheng-Ji Yang posted:

lol apparently the army corp of engineers has refused to open it

https://www.nola.com/news/hurricane/article_0cb536be-a4c8-11e9-8be4-5786c3c46116.html

redneck nazgul posted:

mastershakeman posted:

I'm obviously an idiot to have thought the government would try to save a city of 500k (60% black) over a city of 10k (80% white)

oystertoadfish posted:

there's something to be said for building a weir that's at a specific height and letting the river tell you when to use it by pouring over it due to gravity. nobody can corrupt that process

and i think they're actually trying to minimize the damage from this flood and they think keeping that spillway closed is the way to go. they know more about this system than we do... theyre gonna look pretty bad if the river levees break though, to say the least

Al! posted:

i wonder if it's shaping up to be an irene-sandy scenario where the first one is predicted to be apocalyptic but is relatively mild and then everyone will go "hey remember barry? we'll be fine" and get their poo poo totally rocked when the next one comes in this season.

Perry Mason Jar posted:

Yes, this. The city knows what they're doing. Katrina could've been a humanitarian disaster but the city knew exactly what to do, and after Katrina they've made huge improvements to their infrastructure to stop anything like Katrina impacting the city like that again.

Perry Mason Jar posted:

Yes, this. The city knows what they're doing. Katrina could've been a humanitarian disaster but the city knew exactly what to do, and after Katrina they've made huge improvements to their infrastructure to stop anything like Katrina impacting the city like that again.

oystertoadfish posted:

there's something to be said for building a weir that's at a specific height and letting the river tell you when to use it by pouring over it due to gravity. nobody can corrupt that process

and i think they're actually trying to minimize the damage from this flood and they think keeping that spillway closed is the way to go. they know more about this system than we do... theyre gonna look pretty bad if the river levees break though, to say the least

Source4Leko posted:

How high are these leeves going to end up? 50 feet?

H.P. Hovercraft posted:

yeah the poor army corps of engineers reputation would sure be tarnished in new orleans if their negligence allowed it to massively flood

CODChimera posted:

I'm watching the news livestream and being in one of these raised houses during a storm must be genuinely terrifying

CODChimera posted:

I'm watching the news livestream and being in one of these raised houses during a storm must be genuinely terrifying

Gunshow Poophole posted:

Erik Larsen's book Isaac's Storm is a really good sort of historical speculative accounting of the kind of batshit weirdness and desperation of being in this situation. if you want to read about Weather Politics for several too many pages.

Sheng-Ji Yang posted:

its very likely not going to go over the levees now. if the river levees hold things should be mostly fine.

PostNouveau posted:

They were talking to some dude next to the lake, standing in ankle-deep water, and his son was driving up to high ground, but he was staying with his house on stilts, and why dude? You got somewhere to go, so go.

PostNouveau posted:

I'm at relatives', and one of them has a friend in one of those real cajun places way too far south. Under mandatory evacuation right now, but she's not leaving because she has black neighbors and she thinks they'll loot her place if she leaves.

gently caress You And Diebold posted:

Newest orleans

redleader posted:

what are the levees made from? dirt? concrete? does it matter?