re: Mississippi River Flooding - Links & Pictures in 1st Post

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Ummm frick. So unless Old River goes above design capacity or they blow a levee, that 310 kcfs surplus will just keep on trucking down the river and eventually be surplus in New Orleans, putting the kcfs for New Orleans at 24.8% above design capacity (1250 kcfs + 310 kcfs = 1560 kcfs), right?

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Holy shite. Crest at BR projected for May 23rd and the flow rate is projected at 1330 kcfs by May 12th. They haven't projected the kcfs out further than that yet, but the Project Flood capacity is only 1500 kcfs.

Here go hell come.

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"the max numbers for BR and NO"
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It doesn't matter what's open and what isn't. The max flow those places can handle is what it is and the flow at those places is what it is.

Now the projected flow is a different story.

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The numbers I quoted are NOT the "max numbers for BR and NO." These figures are what the system was designed to operate at. I'm sure that there is a fudge factor involved in their calculations. For example, the levees in N.O. are designed to protect to 20', but the levees are higher than 20'. The MR&T Project is designed to allow 1,250 kcps of discharge to pass N.O. safely. River stage at this flow, at the Carrollton Gage, is about 17.0'

These figures are the "triggers" to open the spillways. If the river is projected to flow (discharge volume) at or above 1,500 kcfs in BR, this triggers the opening of the Morganza. If the river discharge is at 1,250 kcfs at the Carrollton Gage, this triggers the opening of the Bonnet Carre. Additional capacity can be diverted from the main water course by increasing the flow of the Old River Control Structures, into the Morganza/West Atchafalaya floodways.

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The numbers I quoted are NOT the "max numbers for BR and NO." These figures are what the system was designed to operate at. I'm sure that there is a fudge factor involved in their calculations. For example, the levees in N.O. are designed to protect to 20', but the levees are higher than 20'. The MR&T Project is designed to allow 1,250 kcps of discharge to pass N.O. safely. River stage at this flow, at the Carrollton Gage, is about 17.0' These figures are the "triggers" to open the spillways. If the river is projected to flow (discharge volume) at or above 1,500 kcfs in BR, this triggers the opening of the Morganza. If the river discharge is at 1,250 kcfs at the Carrollton Gage, this triggers the opening of the Bonnet Carre. Additional capacity can be diverted from the main water course by increasing the flow of the Old River Control Structures, into the Morganza/West Atchafalaya floodways.

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Ok. So New Orleans is expected to be at 1280 kcfs by 5/12, which is above the 1250 design capacity. Is this not accounting for flow lost to the BC since it will be open fully by then?

LINK

@TIGERSandFROGS

I didn't see a date on your link. But because there is no flat spot or downtick, in either stage or flow, for early next week, I'm guessing it was prepared before the opening of the Bonnet Carre was made official. Emphasis on GUESSING!

My gut feeling is that N.O. will be fine. I'm not as confident about some of the folks upstream and in the Atchafalaya Basin.

TIGERSandFROGS blew my mind.

Can anyone dumb his post own for me?

Is the shite gonna crumble?

Am I gonna DIEEEEEEEEEE!!!!!??????

I knew it...

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So we are most likely not going to know anything substantial as to how bad it will be for at least a week or so? A lot depending on future rain amounts?

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If it didn't rain anywhere from Arkansas and western TN to the south for the next three weeks, that would probably be a good thing. North of there, the river has crested or is cresting. Shouldn't make much difference.

The link below shows the potential flooding in LA if the Morganza is opened to 50% capacity and the Bonnet Carre to 100%. I'm not sure what flow they are figuring through the ORCS.

If you've got property in the Morganza Floodway or in the Atchafalaya Basin, I'd be moving my shite in a hurry.

LINK

TBH, if it came down to deciding between the two (which I don't think is in the cards at all), they'll probably let even NO go rather than let the river completely divert.

A river diversion is *that* bad

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I hope you're right about those not accounting for the BC opening. Your line if thinking seems correct for sure, but then again if the rate was going to be increasing faster during that time, and opening would just slow the rate of increase, perhaps it would then drop the rate to the original plot's slope

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I wasn't trying to break your balls about the link. I also said I was guessing, but I've tried to look at this logically. Absent of all other data, there's nothing wrong with your logic. But what makes me think that the projection in the link does not account for the Bonnet Carre opening is that the river doesn't crest at Memphis until 11May2011. I'll admit that it's possible that a slug of water is travelling downstrean ahead of the main crest, but I still think that there would be a downtick. When they opened the Birds Point New Madrid Floodway, the river fell something like 2' in about 24 hours at Cairo, IL. (That's also why the crest dates were pushed back a day or two in some downstream locations. That water will re-enter the river after moving through the floodway at a lower velocity.)