Pray for Louisiana

[DoomsDave]

Things are looking really bad in LA.

http://www.msn.com/en-us/weather/topstories/louisiana-under-water/ss-BBvF9Lz?li=BBnb7Kz#image=3

10 dead and thousands evacuated.

Praying for you all.

 

[Palmaceae]

Yes praying for safety to all involved.

[PalmTreeDude]

My prayers go out to Louisiana. 

[_Keith]

This was catastrophic. I am fine, but I countless friends and a few family members who are not.   For those who keep up with the national news, you know that Louisiana is not stranger to flooding, but this was a true anomaly flooding areas that had never flooded in recorded history.   Here is a well balanced article on the subject.

http://arstechnica.com/science/2016/08/louisianas-1000-year-floods-inundated-80000-homes-and-businesses/

[Funkthulhu]

From a purely geological/geomorphological viewpoint, the moment we started to channelize the river this was going to happen.  We've kept the largest river on the continent confined to its current channel for nearly a century.  Normally, this channel would move back and forth over the delta, each subsequent flooding would add to the deposition of new land, or add elevation to existing land.

It is a fact of hydrology and sedimentology that deltas will dewater themselves over time.  Basically, even if packed very densely during deposition there is still a lot of water between the grains of sand and mud.  Over time and under pressure from material above the water is squeezed out.  It's not much, but it adds up, and can cause large areas to fall from centimeters to meters over a human lifetime.  

When the river was channelized we lost the recuperative powers of a good flood with regard to land elevation.  In the last 200 years there are areas of Louisiana that have dropped over 5 meters from dewatering.  Case in point, much of the French Quarter in New Orleans is actually now below sea level, and that whole area is becoming our own personal Denmark with regard to sea and groundwater management.  

Now, maybe there is a link to global warming, there is certainly an argument to be made for the additional moisture that can be carried by warmer air.  But that is an argument for another time, perhaps.  What is clear here is that there was a preexisting condition that came to a horrible fruition.  I think it's time we started looking at the likelihood of future disasters before we pay to rebuild in the same place.  And we acknowledge that disasters like this are going to happen more often in the future as we see the 50-100 year fallout of older land management and construction.

But in the end, I hope all the people affected by this catastrophe get the help they need to find a solid footing on higher ground.

Edited August 17, 2016 by Funkthulhu

[_Keith]

8 minutes ago, Funkthulhu said:

From a purely geological/geomorphological viewpoint, the moment we started to channelize the river this was going to happen.  We've kept the largest river on the continent confined to its current channel for nearly a century.  Normally, this channel would move back and forth over the delta, each subsequent flooding would add to the deposition of new land, or add elevation to existing land.

It is a fact of hydrology and sedimentology that deltas will dewater themselves over time.  Basically, even if packed very densely during deposition there is still a lot of water between the grains of sand and mud.  Over time and under pressure from material above the water is squeezed out.  It's not much, but it adds up, and can cause large areas to fall from centimeters to meters over a human lifetime.  

When the river was channelized we lost the recuperative powers of a good flood with regard to land elevation.  In the last 200 years there are areas of Louisiana that have dropped over 5 meters from dewatering.  Case in point, much of the French Quarter in New Orleans is actually now below sea level, and that whole area is becoming our own personal Denmark with regard to sea and groundwater management.  

Now, maybe there is a link to global warming, there is certainly an argument to be made for the additional moisture that can be carried by warmer air.  But that is an argument for another time, perhaps.  What is clear here is that there was a preexisting condition that came to a horrible fruition.  I think it's time we started looking at the likelihood of future disasters before we pay to rebuild in the same place.  And we acknowledge that disasters like this are going to happen more often in the future as we see the 50-100 year fallout of older land management and construction.

But in the end, I hope all the people affected by this catastrophe get the help they need to find a solid footing on higher ground.

For the average tropical storm surge + rain event you are right on target.   In the case those areas were largely spared.  Notice you saw nothing about New Orleans flooding.   This event dropped so much rain that the inland rivers and some relatively high areas (for Louisiana) flooded as those rivers simply exceeded capacity.  If there had been storm surge or even strong southerly winds, and thank God there was not, the event would have been far far worse.

[Funkthulhu]

I think a lot of people don't realize that a Storm Surge is a literal significant temporary rise in actual sea-level.  

Katrina was the highest measured in the states, at over 8 meters in places.

A large storm surge associated with this event in Baton Rouge may have resulted in 700 or 7000 deaths instead of 7.  Not because they're at sea-level, but because all the rivers in the area would have had even less room to drain away the rain.

Edited August 17, 2016 by Funkthulhu

[Funkthulhu]

EXCELLENT ARTICLE for reference to what we're talking about!  

https://medium.com/matter/louisiana-loses-its-boot-b55b3bd52d1e#.gw0n9v86n 

[DoomsDave]

7 hours ago, _Keith said:

This was catastrophic. I am fine, but I countless friends and a few family members who are not.   For those who keep up with the national news, you know that Louisiana is not stranger to flooding, but this was a true anomaly flooding areas that had never flooded in recorded history.   Here is a well balanced article on the subject.

http://arstechnica.com/science/2016/08/louisianas-1000-year-floods-inundated-80000-homes-and-businesses/

Glad to hear you're okay!

Hmm. In the U.S., recorded history is pretty much an eyeblink. The good people of the Pacific Northwest are coming to realize that, too. (As we are here along the Cote d'La La . . . )

 

[DoomsDave]

2 hours ago, Funkthulhu said:

EXCELLENT ARTICLE for reference to what we're talking about!  

https://medium.com/matter/louisiana-loses-its-boot-b55b3bd52d1e#.gw0n9v86n 

Fascinating indeed!

It's a long printout . . .

[Funkthulhu]

15 hours ago, DoomsDave said:

Fascinating indeed!

It's a long printout . . .

Y'know you can read those on the screen, right?  

[DoomsDave]

8 minutes ago, Funkthulhu said:

Y'know you can read those on the screen, right?  

Not all of us have laptops.

Screen is better, since the printout wasn't any good with the pictures.

Like Playboy, it's for the articles . . . . .

[_Keith]

A picture is worth a thousand words.   Here you can see exactly what happened and it is pure and simple.  More rain in a 24-36 hour period than the inland rivers could drain off.

http://geodesy.noaa.gov/storm_archive/storms/aug2016_lafloods/index.html

[peachy]

Having gone through the horror of massive flooding 5 years ago my heart goes to out to all the people in the affected areas. I just hope the water recedes soon and people are safe.

[_Keith]

We have several Louisiana members and one board member in Louisiana.  I am overwhelmed at the outpouring of concern noted on PT.   

[topwater]

If not for happenstance it could be southeast Texas, we lucked out. How far are you from the bad stuff Keith?

[_Keith]

1 hour ago, topwater said:

If not for happenstance it could be southeast Texas, we lucked out. How far are you from the bad stuff Keith?

I am very close to the bad stuff, but on high ground.   And not so long ago it was Texas, remember Allison in 2001?

[topwater]

OMG, yes.  Hopefully the worst is over for you guys.  

[PalmatierMeg]

My thoughts and prayers for everyone in LA.

[DoomsDave]

What a nasty summer this is turning out to be.

[_Keith]

On the positive side my 2 newly planted Livistona australis and Arenga engleri are thriving.  That engleri was struggling too.  It loves clouds and rain.  

[Tropicdoc]

My dad has a friend with a rain gauge in his yard from Friday morning to Sunday morning he collected 32 inches of rain! I would imagine that kind of rainfall anywhere in the world would cause river flooding.

[Las Palmas Norte]

Yikes ... that's nearly a years worth of rain here, and I live  in the PNW !!!  

Cheers, Barrie.

[_Rob_]

Strength to all in LA. We feel with you. This kind of disaster unites the world.

We Dutchies have been battling the water for centuries and will always feel connected with LA - I also have some friends in the area - all fine but house in 4 feet of water and 4 vehicles lost incl an RV).

PS Above someone mentioned Denmark - im guessing that was meant to be the Netherlands.... Denmark is mostly way above sealevel