World’s Worst Regional River Floods

By: Christopher C. Burt , 8:19 PM GMT on May 14, 2011

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World’s Worst Regional River Floods

With the lower and middle Mississippi River having approached and, in some locations surpassed, its greatest flood stage on record I thought it timely to compare this spring’s event with those in the past from around the world. Aside from drought-induced famines no weather-related natural disaster has exacted the toll that massive regional floods have on the earth’s population.

Huang He (Yellow) and Yangtze Rivers, China

The deadliest river in the world, the Huang He (Yellow River) of China, has taken the lives of as many as seven million people over the course of the past 150 years. This included the single deadliest flood of all time that occurred in 1931 and drowned between one and four million in China’s Shandong and Henan Provinces (many of these fatalities were also the result of an ensuing famine). The same year the Yangtze River also flooded, killing another 145,000. In 1887, the Huang He caused the deaths of 900,000 to two million during another of the river’s catastrophic flood events.



A riverboat rests high and dry along the shore of the Yangtze River following a flood in the 1930s. The Yangtze has sometimes risen up to 100 feet above its normal stage.

The cause of these floods is silt washed into the river from loess deposits in the river headwaters (see this link for an explanation of loess deposits) that have elevated the river above the surrounding flood plain and so dikes have been built to contain the river’s course, thus when the dikes are overwhelmed the ensuing flood quickly submerges the thousand of square miles of neighboring flood plains. In the past decade the Three Gorges Dam Project has so far been successful in mitigating the river’s flooding.



A dam on the Huang He (Yellow River) releases a massive wall of water in order to flush silt out of the river’s lower reaches. The silt-causing loess deposits are the reason for the river’s eponymous name.

Floods have changed the course of the Huang He many times as this map below illustrates.



Rivers of the Gangetic Plain of India and Bangladesh

Given the Ganges River and its tributaries flood on a regular basis and that this part of the world is prone to mass casualties in the event of a natural disaster, it is interesting that no truly catastrophic flood is on record for the region. The deadliest such flood in modern history was that of September 1988, when an estimated 2,000 - 5,000 died in West Bengal State of India and in Bangladesh following four months of torrential monsoon rains.

The Indus River of Pakistan occasionally floods as well, but never in as spectacular fashion as it did last summer (August 2010) when up to 20 million people were displaced and over 1,500 died.

Rivers of Europe

The most flood-prone River in Europe is the River Arno in Italy. It has produced a catastrophic flood about once every hundred years for the past millennia. The last such was in November 1966 when Florence was inundated and 149 lives were lost. The flood was best known for the terrible destruction wrought to Florence’s cultural heritage including severe damage to the world-famous Uffizi Gallery, the primary art museum of Florence.



The Arno River rages out of control through the city of Florence, Italy during the flood of 1966 Photo by Balthazar Korab.

The deadliest river flood in European history was that of the River Neva when it overflowed its banks in and around St. Petersburg, Russia on November 19, 1824. Over 10,000 were downed. Virtually every dwelling in the city was flooded to the top of its first story including the Winter Palace of the czar and his family.

Africa

The Nile River has flooded virtually every year since time immemorial. Since the flooding is anticipated there has never been a catastrophic (in terms of human casualties) flood along its length. The possible exception to this was in August 1988 when Khartoum, Sudan was flooded destroying a refugee shantytown that had been erected along the banks of the Nile. Over 100 drowned according to press reports.

Mozambique and South Africa have had several devastating river floods in recent years as a result of tropical storms. The worst such was in 2000 when two tropical storms that made landfall between February and April that year unleashed torrents of rain and many rivers went into flood. Over 800 died as a result.



Flooding in Mozambique in 2000 trapped hundreds on this bridge leading to the town of Xai-xai. Photo from AP.

South America

The Amazon River, in spite of its vast size and drainage basin, rarely floods in an unexpected way. This is because its two principle tributaries, the Rio Negro and the Madeira River lie on opposite sides of the equator and experience different rainy seasons, so their contribution to the Amazon flowage tend to cancel one another out. Also, the Amazon has a series of large, shallow lakes along its way that act as a natural flood control mechanism. All of South America’s worst flood disasters have been the result of flash floods in mountainous regions (as happened in Brazil earlier this year and has been on-going in Columbia since last November).

North America

Obviously, the Mississippi River is the most flood-prone river on the continent and second in the world only to the rivers of China. So far (as of this writing), the highest flood stages on record this past week have not yet resulted in catastrophic flood damage or loss of lives. This, of course, is a result of the amazing system of levees and flood-control projects along its length. The last time the river flooded (along with the Missouri River) in a major way was in 1993. The Great Flood of 1993 resulted in $26 billion in damage (in current dollars—actual amount at time was $18 billion) which qualifies this as the costliest river flood in U.S. history.



The Missouri River floods a highway interchange near the Jefferson City, Missouri Airport on July 30, 1993. Photo from the Missouri Highway and Transportation Department.

The flood of 1927, however, killed and displaced far more people than the flood of 1993 even though the crests reached were not as high as those attained in 1993 or now. The death toll from the 1927 flood has variously been reported at between 246 and 313 and that of 1993 at 48. In 1927 some 750,000 were displaced versus 55,000 in 1993.



Flood refugees crowd onto an evacuation barge on the Sunflower River in western Mississippi during the 1927 flood. Photo from Library of Congress.

Deadliest Regional River Flood in U.S. History
The deadliest regional river flood in U.S. history was that of the Ohio River in March 1913. Four days of torrential rain (up to 11.16” in Bellefontaine) sent most of Ohio’s rivers into flood. The Miami River in Dayton crested some 34 feet above flood stage inundating the city and killing 123. All told 467 lives were lost in the region.




A map and table produced by USGS illustrate the rivers of risk in the United States and some of the historical floods of the 20th century.

Noah’s Flood

Obviously, great river floods have occurred in times prior to the modern records I list above. The historical event of the so-called ‘biblical flood of Noah’ has its basis in fact. Archeological evidence shows that at some time around 2400 BC the Tigris-Euphrates Valley was entirely submerged and silt some 10 feet deep was deposited in a very short amount of time.

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14. Christopher C. Burt , Weather Historian
12:31 AM GMT on May 22, 2011
Quoting MidwestJack:
What's the reference for the 2400 BC drowning of the Tigris / Euphrates valley with 10 ft silt deposits? I'm curious to read more about that!


See:

http://ncse.com/cej/8/2/flood-mesopotamian-archae ological-evidence

However, the date may have been closer to 2700BC not 2400BC.
Member Since: February 15, 2006 Posts: 266 Comments: 248
13. MidwestJack
5:33 AM GMT on May 21, 2011
What's the reference for the 2400 BC drowning of the Tigris / Euphrates valley with 10 ft silt deposits? I'm curious to read more about that!
Member Since: July 5, 2008 Posts: 0 Comments: 1
12. Neapolitan
5:57 PM GMT on May 20, 2011
Nice work, Chris.

I spent most of July and August of 1976 with some family in Loveland, Colorado, so I just happened to be in town on the 31st when the Big Thompson river flooded and killed those 140 or so people, mostly campers (in the list above). I was a kid, of course, but was fascinated by the weather even then, and I very well remember a huge cumulonimbus sitting up in the mountains late in the afternoon and into the evening. Turns out that cloud dropped nearly a foot of rain across a pretty large area in just four hours or so, and all that water had nowhere to go but into the steep and narrow Big Thompson canyon.

We and many other people went down by the river the next morning where it runs through the south edge of town. The water had mostly receded by then, but it was still muddy. And, sadly, odds bits and pieces of things were scattered along its banks: shirts, shoes, bread wrappers, beer cans, and that sort of thing. It was definitely eerie.
Member Since: November 8, 2009 Posts: 4 Comments: 13275
11. Midweststorm
4:56 PM GMT on May 20, 2011
Excellent post! I recall the flood of 93 very well. Even though I lived in Kansas city, I remember a lot of the area rivers being up much more than normal. I also remember that it didnt rain on only a few days that summer.
Member Since: August 5, 2007 Posts: 2 Comments: 92
9. Christopher C. Burt , Weather Historian
6:29 AM GMT on May 18, 2011
Quoting raingarden:
Has the Irrawaddy or Mekong Rivers ever flooded to the point of disaster?


No, there has never been a a flood of catastrophic proportions in recorded history along either of these two rivers although extensive flooding occurs regularly on both rivers.

The population in their flood plains are well prepared for the river's rises. The lower reaches of the Mekong have the vast lake of Tonle Sap in Cambodia to absorb high water and the Irrawaddy flows through the semi-arid region of central Burma to mitigate the possibility of downstream flooding in the wetter and heavily populated region of the Irrawaddy Delta where any 'great' flood could potentially cause great damage.
Member Since: February 15, 2006 Posts: 266 Comments: 248
8. raingarden
2:52 AM GMT on May 18, 2011
Has the Irrawaddy or Mekong Rivers ever flooded to the point of disaster?
Member Since: April 10, 2011 Posts: 0 Comments: 2
7. Christopher C. Burt , Weather Historian
10:28 PM GMT on May 17, 2011
Quoting 1900hurricane:
Speaking of Areal Floods, I was wondering how much you knew about the December 1913 Floods in Texas. Records from that flood still stand all along the Brazos and Colorado Rivers and I even read that the individual floods on both of the rivers were so high that they spilled out of their drainage basins and even temporarily merged with each other! While this is not confirmed, the small San Bernard River, which lies between the two larger rivers near the coast, also recorded it's highest stage during the flood, despite curiously receiving little rain in the area during the event, which can be seen in the table below for the Colorado Basin below La Grange and the Brazos River below Brenham (click on the image for the full-size version):



I'm afraid I don't know much about this famous flood off the top of my head. Checking in George W. Bomar's superb book 'Texas Weather' he list this flood as the 2nd deadliest in Texas history with 177 deaths attributed to it, just behind the famous deluge of Sept. 8-10, 1921 when 36.4" of rain fell in Thrall over just 18 hours and the ensuing flood killed 215.
Member Since: February 15, 2006 Posts: 266 Comments: 248
6. 1900hurricane
9:40 PM GMT on May 17, 2011
Speaking of Areal Floods, I was wondering how much you knew about the December 1913 Floods in Texas. Records from that flood still stand all along the Brazos and Colorado Rivers and I even read that the individual floods on both of the rivers were so high that they spilled out of their drainage basins and even temporarily merged with each other! While this is not confirmed, the small San Bernard River, which lies between the two larger rivers near the coast, also recorded it's highest stage during the flood, despite curiously receiving little rain in the area during the event, which can be seen in the table below for the Colorado Basin below La Grange and the Brazos River below Brenham (click on the image for the full-size version):

Member Since: August 2, 2006 Posts: 45 Comments: 11556
5. pottery
12:34 AM GMT on May 17, 2011
Very nice!
Thank you.
Member Since: October 24, 2005 Posts: 0 Comments: 23080
4. nocaneindy
12:08 AM GMT on May 17, 2011
Yep another top of the line blog! I'm so very glad you joined this community. I can't wait to see what ya got for us in regards to hurricanes!
Member Since: September 21, 2007 Posts: 34 Comments: 515
3. barbamz
8:47 PM GMT on May 15, 2011
Thanks a lot, very interesting overview.
Member Since: October 25, 2008 Posts: 43 Comments: 5020
2. TomTaylor
8:43 PM GMT on May 15, 2011
thanks weatherhistorian

fascinating read, as always
Member Since: August 24, 2010 Posts: 19 Comments: 4357
1. ajcamsmom2
12:43 PM GMT on May 15, 2011
Very interesting...Thank you!
Member Since: March 15, 2008 Posts: 4 Comments: 2490

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About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.