Stories tagged flooding

Aug
22
2012

Mississippi River: Water levels in 2012 have dropped to record lows after a season of extreme flooding in 2011.
Mississippi River: Water levels in 2012 have dropped to record lows after a season of extreme flooding in 2011.Courtesy Mark Ryan
What a difference a year can make. The water levels of the Mississippi River this year are at their lowest on record, yet just last year, in the spring of 2011, extreme flooding of Ol’ Muddy was a source of deep concern for those living along its eroding banks.

NASA’s Earth Observatory page shows the striking difference in the river’s appearance near Memphis using two Landsat satellite images taken a year apart. One photograph shows the river in August of 2011 just after the river returned to its pre-flood levels. But if you compare it to a more recent image, its obvious that water levels have gone the opposite direction from flooding. The site conveniently allows you to combine the two views into a single image with a scroll bar you can manipulate back and forth over to see “then and now” differences (just click on the "View Image Comparison" button below the photos).

The lower levels of 2012 have allowed the US Army Corp of Engineers to patch and reinforce some of the levees built along the river to hold back flood waters, but tons of sediment from last year’s floods have reshaped river traffic corridors, reducing barge holding capacities and adding additional shipping costs.

SOURCE
NASA’s Earth Observatory site

May
12
2011

Mississippi River Levee in Baton Rouge, LA, taken May 11th 2011.: Panorama of the Mississippi River levee in Baton Rouge, LA near Louisiana State University, taken May 11th 2011.
Mississippi River Levee in Baton Rouge, LA, taken May 11th 2011.: Panorama of the Mississippi River levee in Baton Rouge, LA near Louisiana State University, taken May 11th 2011.Courtesy Azure Bevington
You might have heard about the terrible flooding that is occurring all along the Mighty Mississippi. As I write this I am sitting in Baton Rouge, Louisiana hoping the levees will hold. Normally the river in Baton Rouge is far below the tops of the levees. Flood stage, which is the water level at which the river would begin to flood surrounding areas without the levees acting as barriers, is 35 ft. Right now the water level is 42.8 ft and has risen 8 ft in just the last week. It is projected to crest at 47.5 ft and remain at that level for 8 to 10 days; this is higher than the previous record set in May 1927 of 47.28 ft. The tops of the levees that protect Baton Rouge are between 47 and 50 ft, they are currently sandbagging in areas less than 48 ft. Besides the possibility of overtopping there are also other problems that we need to look out for. When the river level remains high for an extended period of time the water can seep in and begin to saturate the soil, this can possibly weaken the levee structure. There is also the possibility of water going under the levee; this can result in sand boils, where the water bubbles up through the soil. It is very unlikely that this will happen, as the levees are strong and well constructed, but we need to be on the lookout for any problems.

Here in Baton Rouge we are much better off than many who live in communities within the Atchafalaya Basin, where the expected opening of the Morganza spillway could cause flooding of over 3 million acres (Click here to see a map of projected flooding in the basin) Many of these folks have already begun to sandbag their homes and to prepare to leave the area. The Morganza spillway is a large controlled gated structure that will divert water from the Mississippi River into the Atchafalaya Basin. The Atchafalaya Basin is a low lying cypress swamp that normally receives 30% of the flow of the Mississippi River through the Old River Control structure through the Atchafalaya River that winds its way through the swamp. This flood is projected to be larger than the 1973 flood and possibly even larger than the 1927 flood that devastated communities along the river, and brought about the passage of Flood Control Act of 1928. The magnitude of this year’s flood has already resulted in the opening of the Bonnet Carré spillway which diverts water into Lake Pontchartrain, this reduces the water levels as the River flows past New Orleans.

Stay tuned for updates on the flooding in Louisiana.

Have any of you been affected by the flood waters?

Sometime tonight the US Army Corps of Engineers will blow up a levee at the confluence of the Mississippi and Ohio Rivers.

All that rain that fell in April has both rivers swollen WAY past flood stage. (Water levels outside Cairo, Illinois, were at 61.4' this afternoon; "flood stage" begins at 40'.)

Major General Michael Walsh, head of the Mississippi River Commission,

"...ordered the intentional breach to alleviate pressure in the river system and to protect Cairo, even though it may lead to the flooding of 130,000 acres of mostly farmland in Missouri."

More later.

Disaster junkies, prepare to be disappointed.

Hydrograph: 4/11/2011, 5pm
Hydrograph: 4/11/2011, 5pmCourtesy Advanced Hydrological Prediction Service

The National Weather Service says that the Mississippi River at downtown St. Paul has crested, again, at 18.71'. (Previous crest was on 3/30 at 19.1'.)

Forecasters say that the river will remain at this level for a few days before falling at the end of the week. And they caution that the model only includes precipitation anticipated in the next 24 hours. A lot of rain in the next few days could cause the river to rise. Again.

The river level here at downtown St. Paul has been going down since the crest on 3/30 at 19.1'. We're holding now at about 17.3', and the National Weather Service predicts that the trend will bottom out tonight at around 17.2' before the river starts rising again. We're expecting a second crest at about 19.5' on the evening of 4/10, but that prediction doesn't take into account any rain we might get later on this week. Stay tuned...

We've peaked

by Liza on Mar. 30th, 2011

The Mississippi River at downtown St. Paul crested this morning around 10:00 at 19.1 feet, making this year's flood the 8th highest flood of record. So far.

Buildings on Harriet Island: 2011 crest, March 30: 19.1 feet
Buildings on Harriet Island: 2011 crest, March 30: 19.1 feetCourtesy City of St. Paul

You see, we're not out of the woods yet. There's a good possibility that we may see a second crest, and the extent of that flooding will be determined by how quickly temperatures warm up (and stay warm) and whether or not we get any big rainstorms.

Stay tuned...

The Mississippi River @ downtown St. Paul is at "action stage" right now - 12.63' - headed to "flood stage" by midnight. Yesterday, it was rising about an inch an hour, but the cold has slowed things down just a bit. And the continued cold means that the river should crest (the first time, anyway) quite a bit lower than earlier predictions. Visit the Hydrological Prediction Service for details, or follow the whole flood saga on Science Buzz.

3-23-11, 8:30pm forecast: In this ONE respect, winter's comeback is a good thing...
3-23-11, 8:30pm forecast: In this ONE respect, winter's comeback is a good thing...Courtesy National Weather Service

A new gigapan is up. It is a very snowy version with much higher water. What a difference two days makes...

http://gigapan.org/gigapans/73337/

BTW: pay special attention to the lack of a really long train that didn't pass by. :)

Here is a gigapan shot I took of the river yesterday. I will try to take a panorama every other day(at least). I intend to capture more of the river west in future shots.

http://gigapan.org/gigapans/73228/

BTW: pay special attention to the crazy time capture of a really long train that was passing by.

Please pass on the link to whomever you feel would be interested.

The National Weather Service has updated the 7-day outlook for the Mississippi River at downtown St. Paul. So far, the news is good: we're looking at 18.3' by the end of the week -- equivalent to last year's flood event, and a hassle, surely, but nowhere near the record. However,

"SIGNIFICANT UNCERTAINTY REMAINS ABOUT HOW MUCH SNOW WILL MELT THROUGH
TUESDAY...AND HOW MUCH RAIN AND SNOW WILL FALL...AND HOW MUCH OF THIS
COMBINED TOTAL WATER WILL ACTUALLY MAKE IT INTO THE RIVER SYSTEMS...BEFORE
COLDER AIR MOVES INTO THE AREA LATER IN THE WEEK.

THE CURRENT RIVER FORECASTS ONLY TAKE INTO ACCOUNT 24 HOURS OF FORECAST
PRECIPITATION...HENCE THROUGH 7 AM ON MONDAY. SO THESE FORECAST DO NOT
INCLUDE THE PRECIPITATION EVENT EXPECTED TO IMPACT THE AREA ON TUESDAY
AND WEDNESDAY. ADDITIONAL RAINFALL MAY CAUSE RIVER LEVELS TO RISE EVEN
HIGHER THAN CURRENTLY FORECAST.THE NATIONAL WEATHER SERVICE WILL MONITOR
THIS DEVELOPING SITUATION AND ISSUE FOLLOW UP STATEMENTS."

So stay tuned. The 7-day outlook gets updated as needed.

Plot showing 7-day forecast issued at 8:45 pm, 3/20: 18.3' is WAY lower than 26.4'. But this forecast doesn't take into account the rain/snow we're going to get this week. A heavy rain could take us back into record territory.
Plot showing 7-day forecast issued at 8:45 pm, 3/20: 18.3' is WAY lower than 26.4'. But this forecast doesn't take into account the rain/snow we're going to get this week. A heavy rain could take us back into record territory.Courtesy Advanced Hydrologic Prediction Service