Red River rising: 18th consecutive year of flooding--why?

By: Dr. Jeff Masters , 3:08 PM GMT on March 19, 2010

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The Red River at Fargo, North Dakota continues to rise, with a peak expected Sunday at the 4th highest flood level observed in the past century. "Major" flood level is 30 feet, which the river surpassed on Wednesday, and the river is expected to crest near 38 feet on Sunday, just 2.8 feet below the record set last year. Flood stage is eighteen feet, and the Red River has now reached flood stage at Fargo for eighteen consecutive years, according to the U.S. Army Corps of Engineers. Prior to this remarkable stretch of flooding (which began in 1993), the river flooded in just 29 of 90 years. This year's flood is rated as somewhere between a 50-year and 100-year flood. Last year's record flood was a 100-year flood. The U.S. Army Corps of Engineers lists the 10-year flood level for the Red River at Fargo to be 10,300 cubic feet per second. A 10-year flood, historically, has a 10% chance of occurring in a given year. In the last twenty years, the Red River has had eight 10-year floods--one every 2.5 years, on average. This year is the fourth year out of the past five with a 10-year flood. Clearly, flooding has increased significantly along the Red River over the past twenty years.


Figure 1. Current and forecast flood stage for the Red River of the North at Fargo, ND. You can access images like these using our wundermap for Fargo with the "USGS River" layer turned on. Click on the icon for USGS station 05054000, then hit the "click for graph" link.

Reasons for flooding: landform factors
According the U.S. Geological Survey, the unique landform characteristics of the Red River Valley make it highly susceptible to flooding. These factors include:

1) A relatively shallow and meandering river channel--a shallow channel holds less water and the meandering can cause flow to slow down as the channel makes its turns, causing over-bank flooding.

2) A gentle slope (averaging 0.5 to 1.5 feet per mile) that inhibits channel flow and encourages overland flooding or water "ponding" (especially on even, saturated ground) in the basin.

3) The northerly direction of flow--flow in the Red River travels from south (upstream) to north (downstream). The direction of flow becomes a critical factor in the spring when the southern (upstream) part of the Red River has thawed and the northern (downstream) part of the channel is still frozen. As water moves north toward the still frozen river channel, ice jams and substantial backwater flow and flooding can occur.


Figure 2. Peak flow of the Red River at Fargo, North Dakota through time. The two largest flow rates occurred last year (2009), and in 1997. The projected crest for Sunday (red circle) would be fourth greatest flood since reliable records began in 1901. Image credit: U.S. Geological Survey.

Reasons for this year's flood: highly unfavorable weather conditions
The USGS also cites five weather factors that can act to enhance flooding along the Red River. All five of these factors occurred to a significant degree this year:

1) Above-normal amounts of precipitation in the fall of the year that produce high levels of soil moisture, particularly in flat surface areas, in the basin. North Dakota had its 22nd wettest fall in the 115-year record in 2009.

2) Freezing of saturated ground in late fall or early winter, before significant snowfall occurs, that produces a hard, deep frost that limits infiltration of runoff during snowmelt. Fargo had a November that was much warmer than average, followed by a sudden plunge to below-zero temperatures by the second week of December. This froze the saturated ground to a great depth.

3) Above-normal winter snowfall in the basin. North Dakota had a top 15% winter for precipitation, with the period December 2009 - February 2010 ranking 15th wettest in the past 115 years.

4) Above-normal precipitation during snowmelt. Precipitation for March 1 - 18 has been 1.41", compared to the average of 0.61".

5) Above-normal temperatures during snowmelt. High temperatures in Fargo have averaged 6°F warmer than normal for March 1 - 18.

Urbanization increases flooding
Urbanization has had a major impact on increasing flooding not only along the Red River, but in every river basin in the U.S. Many cities and developed areas are located in flood plains next to major rivers and their tributaries. Highways, streets, parking lots, sidewalks, and buildings now cover large areas of the ground that used to absorb excess rain water and slow the rate at which run-off from precipitation and melting snow reached rivers. By developing large portions of our flood plains, run-off now reaches rivers more quickly, generating higher floods.

Building levees and flood defenses increases flood peaks
Defending ourselves against floods has made floods worse. Every time a new levee is built, or an old floodwall raised in height to prevent overtopping, more and more water is forced into the river bed, which raises the height of the flood. Flood waters that used to be able to spread out over their natural flood plains are now forbidden from spilling out over newly developed land in flood plains. For example, proposed improvements to the flood defense system in Fargo could cause a 4 - 10 inch rise in floods immediately downstream from the city, according to the Army Corps of Engineers.

Precipitation is increasing
As the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 IPCC report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. Satellite measurements (Trenberth et al., 2005) have shown a 1.3% per decade increase in water vapor over the global oceans since 1988. Santer et al. (2007) used a climate model to study the relative contribution of natural and human-caused effects on increasing water vapor, and concluded that this increase was "primarily due to human-caused increases in greenhouse gases". This was also the conclusion of Willet et al. (2007). This increase in water vapor has very likely led to an increase in global precipitation. For instance, over the U.S., where we have very good precipitation records, annual average precipitation has increased 7% over the past century (Groisman et al., 2004). Precipitation over the Red River drainage basin increased by about 10 - 20% during the 20th Century (Figure 3.) The same study also found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events over the U.S. in the past century. These are the type of events most likely to cause flooding. Kunkel et al. (2003) also found an increase in heavy precipitation events over the U.S. in recent decades, but noted that heavy precipitation events were nearly as frequent at the end of the 19th century and beginning of the 20th century, though the data is not as reliable back then.


Figure 3. Change in precipitation over the U.S. between 1900 - 2000, from the U.S. Cooperative network. Precipitation in the Red River drainage area increased by 10 - 20% over the 20th century. Image credit: Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends (Groisman et al., 2002).

The future of flooding
As the population continues to expand, development in flood plains and construction of new levees and flood protection systems will continue to push floods to higher heights. With global warming expected to continue and drive ever higher precipitation amounts--falling preferentially in heavy precipitation events--it is highly probable that flooding in the Red River Valley--and over most of the northern 2/3 of the U.S. where precipitation increases are likely--will see higher and more frequent floods. With these higher and more frequent floods comes the increased risk of multi-billion dollar disasters, when a record flood event overwhelms flood defenses and inundates huge areas of developed flood plains. Obviously, we need to make smart decisions to limit development in flood plains to reduce the cost and suffering of these future flooding disasters.

References
Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003, "Temporal variations of extreme precipitation events in the United States: 1895.2000", Geophys. Res. Lett., 30(17), 1900, doi:10.1029/2003GL018052.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64.85.

Milly, P.C.D., R.T. Wetherald, K.A. Dunne, and T.L.Delworth, Increasing risk of great floods in a changing climate", Nature 415, 514-517 (31 January 2002) | doi:10.1038/415514a.

Santer, B.D., C. Mears, F. J. Wentz, K. E. Taylor, P. J. Gleckler, T. M. L. Wigley, T. P. Barnett, J. S. Boyle, W. Brüggemann, N. P. Gillett, S. A. Klein, G. A. Meehl, T. Nozawa, D. W. Pierce, P. A. Stott, W. M. Washington, and M. F. Wehner, 2007, "Identification of human-induced changes in atmospheric moisture content", PNAS 2007 104: 15248-15253.

Trenberth, K.E., J. Fasullo, and L. Smith, 2005: "Trends and variability in column-integrated atmospheric water vapor", Climate Dynamics 24, 741-758.

Willett, K.M., N.P. Gillett, P.D. Jones, and P.W. Thorne, 2007, "Attribution of observed surface humidity changes to human influence", Nature 449, 710-712 (11 October 2007) | doi:10.1038/nature06207.

Links
A good way to track the flooding event is to use our wundermap for the Red River with the USGS River layer turned on.

The Fargo Flood webpage of North Dakota State University, Fargo, has some excellent links.

I'll have a new post on Monday or Tuesday.

Jeff Masters

Red River Flood 2006 (mw25)
The water level of the Red River when I took this photo was 47.2 feet, 19.2 feet above flood stage and the 6th highest level in Grand Forks' history. The river is expected to crest at 47.4 feet on Wednesday morning. Luckily, no homes have been lost in the Grand Forks area as of yet due to the flooding.
Red River Flood 2006
Fargo Flood 2009 - Elm & 15th Ave. N. (tliebenow)
Picture says it all. Clay dike built to contain the Red River in North Fargo.
Fargo Flood 2009 - Elm & 15th Ave. N.

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Quoting altesticstorm10:

The heart of hurricane season begins in early July this year.


SC81, I mean for the Gulf to warm up closer to normal, not to warm up to 85%uFFFD in March. Of course, when April and May come and the sun begins to beat down directly on the Gulf, it shouldn't take too long to warm to normal or slightly above normal SSTs providing that there isn't too much cloudiness.


Lot's factors could kill you early forecast of the heart of hurricane season being in July. Like historical data suggest that rarely ever happens and probably will not happen. We might get one or two more storms than normal. but doubt will see a huge spike in activity. I'll go with September being the heart considering it is the heart of hurricane seasons of the past.

Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting Patrap:
Factors that Lead to Hurricane Intensification
Factors that Lead to Hurricane Intensification


Why did Hurricane Isabel - a powerful 2003 Atlantic hurricane - remain a Category 5 for as long as 3 consecutive days?

This is nearly unprecedented. Much of this has to do with the very warm ocean water that Isabel encountered, and complete lack of destructive winds high in the atmosphere.


Isabel was enchanting. She was the first annular hurricane I ever got to see. Very special.
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Quoting altesticstorm10:

Allow the sun to beat down on it...hard.
be careful what ya wish for hopefully the cloudiness which has been present will continue well into spring keep the temps runnin 2 below right on into the season that would be a better thing than your idea stop scaring people will ya
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Factors that Lead to Hurricane Intensification


Why did Hurricane Isabel - a powerful 2003 Atlantic hurricane - remain a Category 5 for as long as 3 consecutive days?

This is nearly unprecedented. Much of this has to do with the very warm ocean water that Isabel encountered, and complete lack of destructive winds high in the atmosphere.
Member Since: July 3, 2005 Posts: 427 Comments: 129457
Quoting altesticstorm10:

This is prime opportunity for the Gulf to warm up. The Gulf better seize the day...and warm up!


That's not a prime opportunity for the Gulf.

Prime opportunity would be calm conditions and not March. Need more of the direct sun rays to start heating it up. Calm day with strong direct sun rays and good 85 and above would be prime conditions for the gulf to warm up.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Tropical Highlights - October 2005

The pattern of global tropical sea surface temperature (SST) during October featured near-average SSTs everywhere, except negative anomalies in the eastern tropical Pacific (Fig. T18, Table T2). The overall patterns of convection, SSTs, low-level winds and upper-level winds remained near average over the central and eastern tropical Pacific during October 2005 (Figs. T18, T20, T21 and T25), which is consistent with ENSO-neutral conditions.

The oceanic thermocline, measured by the depth of the 20%uFFFDC isotherm along the equator, featured near-average depth in the central Pacific and slightly shallower-than-average depth in the eastern Pacific during October (Figs. T15, T16). Consistent with these conditions, equatorial oceanic temperatures at thermocline depth were near average throughout most of the Pacific and 1-2 oC below average in the eastern Pacific (Fig. T17). The Tahiti - Darwin SOI (Table T1, Fig. T1) was 1.1 during October, due to lower-than-average pressure over Darwin and higher-than-average pressure over Tahiti .

During October, negative OLR anomalies (above-average rainfall amounts) were observed over India , the eastern equatorial Indian Ocean and the North Atlantic/Caribbean Sea (Figs. T25, T26 and E3), the latter was consistent with the very active Atlantic hurricane season.

Member Since: July 3, 2005 Posts: 427 Comments: 129457
Quoting altesticstorm10:
The GOM has been too cloudy so far this spring. Needs some dry air...


What is dry air going to do for the GOM?
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting AstroHurricane001:


Years that had hurricane seasons similar to this one in pre-season conditions (SSTs, atmospheric pressure, etc).


Thank you. I never had understood what that was about. Now that you explain it, it makes perfect sense.
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GFSx
3day


GFSx
4 day


GFS SL
3day
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Quoting altesticstorm10:

No, I'm not...

I have mixed feelings about 2005. It was the most wonderful and the most horrible season simultaneously. I'm a true hurricane lover, though.

The Gulf is averaging 2C colder than normal at this time. It should warm up to normal to slightly above normal by say, mid-May, but you can never be sure...
hopefully we get periods of extensive cloudiness to help keep sst's in check in gom so it dose not get to warm but temps are warmer in lower boc and north yuc shoreline and eddy looks strong
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Quoting Drakoen:


On that thought:

1987...



1992...



2003...

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Quoting altesticstorm10:
Drak, 0-1 is considered neutral to very weak El Nino right?

In that case, ENSO will be there by early April. Isn't it supposed to drop to around 0 by June and then stall near or slightly below the 0 mark through hurricane season?


-0.5C to +0.5C is considered neutral. 0.5C-1.0C is considered a weak El Nino.
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Quoting AstroHurricane001:
I just noticed something: in ALL five analog years above (arguably including 2005), SSTs in the MDR and eastern Caribbean were cooler than they are this year.
Quoting Levi32:


2008 and 2004 are not great analog years for this hurricane season based on the ENSO alone.

That said...using those maps you won't find a single year since satellite SST measurement began in 1982 that was warmer than this year in the eastern MDR. We already know this year set a record in the eastern Atlantic for warm SSTs in February.
i remember posting a note of it myself in feb and began comparision to the 2005 season and will pretty well use 2005 sst in reference to 2010 for the entire season yet to come this has the making to become all time record levels for sst the power is there just need the contact
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Quoting Dodabear:


What is an "analog year?"


Years that had hurricane seasons similar to this one in pre-season conditions (SSTs, atmospheric pressure, etc).
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Quoting atmoaggie:

That's because they aren't analogue years, really. (thinking in terms of El Nino type and strength, here)

No, this one doesn't rival 1998, but that yeras is the closest to the present one. Can you post that same plot for that year?


1998:
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Quoting AstroHurricane001:
I just noticed something: in ALL five analog years above (arguably including 2005), SSTs in the MDR and eastern Caribbean were cooler than they are this year.


What is an "analog year?"
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Quoting AstroHurricane001:
I just noticed something: in ALL five analog years above (arguably including 2005), SSTs in the MDR and eastern Caribbean were cooler than they are this year.


2008 and 2004 are not great analog years for this hurricane season based on the ENSO alone.

That said...using those maps you won't find a single year since satellite SST measurement began in 1982 that was warmer than this year in the eastern MDR. We already know this year set a record in the eastern Atlantic for warm SSTs in February.
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Quoting AstroHurricane001:
I just noticed something: in ALL five analog years above (arguably including 2005), SSTs in the MDR and eastern Caribbean were cooler than they are this year.

That's because they aren't analogue years, really. (thinking in terms of El Nino type and strength, here)

No, this one doesn't rival 1998, but that yeras is the closest to the present one. Can you post that same plot for that year?
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Skye, WU mail. No rush, just a question...
Member Since: February 11, 2010 Posts: 0 Comments: 865
I just noticed something: in ALL five analog years above (arguably including 2005), SSTs in the MDR and eastern Caribbean were cooler than they are this year.
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127. JeffMasters (Admin) 3:38 PM EDT on March 19, 2010

Thank You Dr......Just snagged a few of Lixion Avila's papers......... :)
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Quoting altesticstorm10:

Basically...in 2005, there were several storms in June-August that weren't hurricanes but added to the named storms list so we got deeper into the name list, which led us into the Greek Alphabet. Many of these "filler storms" formed and made landfall in the Bay of Campeche. Examples include Bret, Gert and José.

Storms like that happen EVERY year. See "2009 Atlantic Hurricane Season". Saying small storms like that raised the number of storms inappropriately is insane. What about TS Marco (smallest storm in the Atlantic basin). Is that storm a "filler" storm?

The fact is that every storm named has its place. A season can be destructive whether the first 5 storms are all weak TS and the 6th is a monster Cat 5, or if the first storm is a monster Cat 5 and the rest are all minor TS.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
127. JeffMasters (Admin)
Quoting nrtiwlnvragn:
Dr Masters, your link for "Trends and variability in column-integrated atmospheric water vapor" does not work, at least for me.


Sorry about that, here it is.

A great way to find a paper is to type its name into scholar.google.com. If there is a free version (pdf) of the paper available on the researcher's web site, it will provide a link to that at the right. The main (usually fee-required) link is on the left.

Jeff Masters
2010 March 18 SSTs compared to analog years:

1995...


2004...


2005...


2007...


2008...


Hmm, this looks like an active season in store.
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well how all you girls doing today
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Won't happen but I would rather it remain cooler nearer to the coast during the season to "take the edge off" on any storms that may get into the Gulf this year after traversing through the very robust loop current.
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GOM 120 Hour Surface Current Forecast Model


GOM 120 Hour Salinity Forecast
Model
Member Since: July 3, 2005 Posts: 427 Comments: 129457
GOM 120 Hour Water Surface Temperature Forecast
Model
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Quoting nrtiwlnvragn:


Trends and variability in column-integrated atmospheric water vapor


Thanks a lot Nrt.
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Quoting altesticstorm10:

Better...if we're going to stand a chance at rivaling 2005. A lot of those weak storms in the first half of the hurricane season formed in the Bay of Campeche, padding the stats.


Yeah well I don't want another 2005, I don't think anyone does.
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Quoting altesticstorm10:

Better...if we're going to stand a chance at rivaling 2005. A lot of those weak storms in the first half of the hurricane season formed in the Bay of Campeche, padding the stats.
You WANT to top 2005? Son, you need help...LOL!
Member Since: February 11, 2010 Posts: 0 Comments: 865
Quoting altesticstorm10:


The Gulf refuses to warm a degree.

Dr. Jeff, when does the Gulf warm up?


It is kinda hard for it to warm up with cold air constantly making its way down to the GOMEX. In many areas of FL, it has been the one of the coldest meteorological winters on record. But I agree, it will take no time to warm once April and May come along.
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112. jeffs713 12:11 PM PDT on March 19, 2010
110. huh? I don't understand that comment


that's because it's JFV....

;)
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More conflicting data on global precipitation. This is from the University of Delaware precipitation dataset, from the NOAA Physical Science Division, Earth System Research Laboratory.

Global Precipitation Time-series since 1950:



Notice the general decreasing trend. This dataset actually agrees with the increase in precipitation in the Red River area:

Global Precipitation Time-series for the Red River drainage area since 1950:



So yes precipitation seems to be increasing in that small area, but this seems to be the opposite of what the entire globe is doing, at least according to this dataset, which is an official dataset used by NOAA. Which dataset is correct? They are all incomplete frankly.

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Quoting altesticstorm10:

Gas Prices before Ike: $3.87
Gas Prices after Ike: went down to $1.55


And it was mostly because of the gas prices that the economy dumped. We do not need that again.
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110. huh? I don't understand that comment
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting altesticstorm10:

Gas Prices before Ike: $3.87
Gas Prices after Ike: went down to $1.55

The economy also face-planted after Ike. Not a valid comparison.
Member Since: August 3, 2008 Posts: 16 Comments: 5891

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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