Cover: A man rows past houses flooded by the Yangtze River in Yueyang, Hunan Province, China, July 1998. The flood, one of the worst on 

record, killed more than 4,000 people and drove millions from their homes. (AP/Wide World Photos)
The World’s Largest Floods, Past and Present: 

Their Causes and Magnitudes

By Jim E. O’Connor and John E. Costa 

U.S. Department of the Interior

U.S. Geological Survey

Circular 1254
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

Free on application to the 

U.S. Geological Survey

Branch of Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation: O’Connor, J.E., and Costa, J.E., 2004, The world’s largest floods, past and present—Their causes and 

magnitudes: U.S. Geological Survey Circular 1254, 13 p.
 iii

CONTENTS

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

The Largest Floods of the Quaternary Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Floods from Ice-Dammed Lakes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Basin-Breach Floods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Floods Related to Volcanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Floods from Breached Landslide Dams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Ice-Jam Floods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Large Meteorological Floods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Floods, Landscapes, and Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Selected References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figures

1. Most of the largest known floods of the Quaternary Period resulted from breaching

of dams formed by glaciers or landslides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2. The late-Pleistocene Missoula floods in the Pacific Northwestern United States were 

some of the largest ever to have occurred on Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

3. The Lake Bonneville flood of about 14,500 years ago resulted from nearly 5,000 cubic kilometers

of water spilling out of the Great Basin and into the Snake River drainage . . . . . . . . . . . . . . . . . . . . . . . . . .4

4. The Bridge of the Gods landslide slid down from the north wall of the Columbia River Gorge

sometime between 1400 and 1465 A.D., blocking the Columbia River to a depth of 70–80 meters . . . .6

5. Rivers with drainage areas larger than 500,000 square kilometers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

6. In general, larger river basins produce larger floods, but larger unit discharges in the 

moist tropics can result in floods of disproportionately large size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

7. Nearly all of the largest floods caused by rainfall have occurred in basins south of latitude 

40 degrees N. North of that, snowmelt- and ice-jam-related floods have predominated. . . . . . . . . . . .11

Tables

1. Quaternary floods with discharges greater than 100,000 cubic meters per second. . . . . . . . . . . . . . . . . .3

2. Largest meteorologic floods from river basins larger than about 500,000 square kilometers . . . . . . . .10
iv 

Conversion Factors

Multiply By To obtain

Length

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi) 

Area

square kilometer (km2) 0.3861 square mile (mi2)

Volume

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s) 

cubic kilometer (km3) 0.2399 cubic mile (mi3) 

Geologic Time Terms

Quaternary Period: About 1.8 million years ago to the present

Pleistocene Epoch: A division of the Quaternary Period extending from about 1.8 million years ago to about 

10,000 years ago. Also known as "The Great Ice Age"

Holocene Epoch: A division of the Quaternary Period extending from about 10,000 years ago to the present
The World's Largest Floods, Past and Present:

Their Causes and Magnitudes

By Jim E. O’Connor and John E. Costa

Introduction

Floods are among the most powerful forces on earth. Human societies worldwide have lived and died with 

floods from the very beginning, spawning a prominent role for floods within legends, religions, and history. 

Inspired by such accounts, geologists, hydrologists, and historians have studied the role of floods on humanity and 

its supporting ecosystems, resulting in new appreciation for the many-faceted role of floods in shaping our world. 

Part of this appreciation stems from ongoing analysis of long-term streamflow measurements, such as those 

recorded by the U.S. Geological Survey’s (USGS) streamflow gaging network. But the recognition of the important role of flooding in shaping our cultural and physical landscape also owes to increased understanding of the 

variety of mechanisms that cause floods and how the types and magnitudes of floods can vary with time and space. 

The USGS has contributed to this understanding through more than a century of diverse research activities on 

many aspects of floods, including their causes, effects, and hazards. This Circular summarizes a facet of this 

research by describing the causes and magnitudes of the world’s largest floods, including those measured and 

described by modern methods in historic times, as well as floods of prehistoric times, for which the only records 

are those left by the floods themselves.

Residents of Dhaka, Bangladesh, carry drinking water as they wade through floodwaters caused by three weeks of 

rain in 1986. Three rivers—the Ganges, Brahmaputra, and Meghna—left their banks, killing more than 1,000 people 

and stranding millions. (AP/Wide World photos)
2 The World’s Largest Floods—Past and Present

Two complimentary types of information are used 

in this summary of the world’s largest floods. The first is 

a compilation of the world's largest known Quaternary 

floods. (The Quaternary Period extends from about 1.8 

million years ago to the present.) Some of these floods 

are known only from geologic evidence and resulted 

from special circumstances during the course of Earth’s 

history. Nevertheless, the records of such floods shed 

light on the great diversity and scales of flood-producing 

mechanisms and their particular settings on earth and 

over geologic time. The second source of information is 

historical measurements of the largest meteorologic 

floods on the largest river basins in the world. These 

floods, which are more within the realm of day-to-day 

human experience, provide a background for discussing 

the geologic, climatologic, and physiographic settings of 

large meteorologic floods on a global basis. 

The Largest Floods of the Quaternary Period

Table 1 and figure 1 summarize the characteristics 

of 27 freshwater floods that had flows greater than 

100,000 m3/s (cubic meters per second) during Quaternary time. Undoubtedly, many more floods of these types 

and magnitudes have occurred but have not yet been 

studied or reported. Nevertheless, this admittedly partial 

list serves as a starting point for some basic inferences on 

the settings of the largest floods in Earth’s history.

The largest known floods of the Quaternary Period 

had peak discharges of nearly 20 million m3/s and 

resulted from breaches of glacial-age ice dams that 

blocked large midcontinent drainage systems during ice 

ages. Most of the other largest documented floods 

resulted from breaches of other types of natural dams, 

including landslide dams, ice dams from smaller glaciers, 

releases from caldera lakes, and ice-jam floods. Only 4 of 

the 27 largest documented floods were primarily the 

result of meteorological conditions and atmospheric 

water sources. However, if only historic events are considered, the proportion of large meteorological floods 

still rises to only 4 of 10.

Floods from Ice-Dammed Lakes

All known terrestrial floods with discharges greater 

than 500,000 m3/s resulted from rapid release of water 

stored behind natural dams or within glaciers (table 1, 

figs. 1 and 2). During the Quaternary Period, blockage of 

large river systems by continental ice sheets has been a 

primary source of landscape-shaping floods. These 

floods include the 17 million m3

/s Missoula floods along 

the Cordilleran Ice Sheet margin in western North America (fig. 2), giant floods along the margins of the Laurentide Ice Sheet in eastern and central North America, and 

more recently discovered giant Pleistocene Epoch floods 

in central Asia. These large ice-age floods involved tremendous volumes of water, enough that their rapid discharge into the oceans may have affected oceanic 

circulation, and hence, global climate. These floods all 

resulted from rapid release of water impounded either in 

(1) preexisting river valleys dammed by ice or (2) proglacial lakes formed along glacial margins. Similar but 

much smaller floods have occurred historically, including 

the 1986 flood of 105,000 m3/s resulting from the failure 

of the dam formed by Hubbard Glacier across Russell 

Fiord, Alaska (table 1).

In June 1986, Hubbard Glacier in southeastern Alaska closed off 

the mouth of Russell Fiord, creating “Russell Lake.” When the lake 

breached the ice dam days later, the ensuing glacial outburst flood 

became the largest such flood in recorded history. (Photograph by 

Rod Marsh, U.S. Geological Survey)

Large ice-age floods occurred during glacial ages 

when ice sheets had advanced across preexisting drainage networks. Known cases are primarily from the northern midlatitudes, where the present geometry of land 

masses supported large continental ice sheets that 

advanced southward and disrupted large drainage systems. The largest floods (in terms of peak discharge) 

have been in areas of significant relief at ice-sheet margins, causing deep valleys to be filled by relatively tall 

ice dams that impounded very large lakes. When tall 

dams cataclysmically fail, such as the 600–1,000 m 

(meters) high ice dams for the Kuray and Missoula floods 

in Asia and North America (table 1), very large peak discharges result because of the exponential dependence of 

discharge on breach depth.
Floods from Ice-Dammed Lakes 3

.

 Table 1. Quaternary floods with discharges greater than 100,000 cubic meters per second

[Pleistocene, about 1.8 million to 10,000 years ago; Holocene, about 10,000 years ago to present. Peak discharge: 106m3/s, million cubic meters per second]

Flood/River Location Date

Peak 

discharge

(106

 m3/s) Mechanism Reference

Kuray Altai, Russia Late Pleistocene 18 Ice-dam failure Baker et al., 1993

Missoula Northwestern USA Late Pleistocene 17 Ice-dam failure O'Connor and Baker, 1992

Darkhat Lakes Mongolia Late Pleistocene 4 Ice-dam failure Rudoy, 1998

Jassater Lakes Altai, Russia Late Pleistocene 2 Ice-dam failure Rudoy, 1998

Yaloman Lakes Altai, Russia Late Pleistocene 2 Ice-dam failure Rudoy, 1998

Ulymon Lakes Altai, Russia Late Pleistocene 1.9 Ice-dam failure Rudoy, 1998

Lake Agassiz Alberta, Canada Early Holocene 1.2 Proglacial-lake overflow Smith and Fisher, 1993

Aniakchak Alaska, USA Late Holocene 1.0 Caldera-lake breach Waythomas et al., 1996

Lake Bonneville Northwestern USA Late Pleistocene 1.0 Lake-basin overflow O'Connor, 1993

Lake Regina Canada/USA Late Pleistocene .8 Ice-dam failure Lord and Kehew, 1987

Jökulsá á Fjöllum Iceland Early Holocene .7 Subglacial volcanic eruption Waitt, 2002

Indus River Pakistan 1841 .54 Landslide-dam failure Shroder et al., 1991

Amazon River Obidos, Brazil 1953 .37 Rainfall Rodier and Roche, 1984

Katla Iceland 1918 .3 Subglacial volcanic eruption Tomasson, 1996

Wabash River Indiana, USA Late Pleistocene .27 Ice-dam failure Vaughn and Ash, 1983

Toutle River Northwestern USA Late Holocene .26 Landslide-dam failure Scott, 1989

Amazon River Obidos, Brazil 1963 .25 Rainfall Rodier and Roche, 1984

Amazon River Obidos, Brazil 1976 .24 Rainfall Rodier and Roche, 1984

Columbia River Northwestern USA About 1450 .22 Landslide-dam failure O'Connor et al., 1996

Lake Agassiz Canada/USA Early Holocene .20 Proglacial-lake overflow Teller and Thorliefson, 

1987

Lena River Kasur, Russia 1967 .19 Ice jam and snowmelt Rodier and Roche, 1984

Lena River Kasur, Russia 1962 .17 Ice jam and snowmelt Rodier and Roche, 1984

Lena River Kasur, Russia 1948 .17 Ice jam and snowmelt Rodier and Roche, 1984

Lake Agassiz Canada/USA Late Pleistocene .13 Ice-dam failure Matsch, 1983

Porcupine River Alaska, USA Late Pleistocene .13 Ice-dam failure Thorson, 1989

Yangtze River China 1870 .11 Rainfall Rodier and Roche, 1984

Russell Fiord Alaska, USA 1986 .10 Ice-dam failure Mayo, 1989

Figure 1. Most of the largest known floods of the Quaternary Period resulted from breaching of dams formed by glaciers or landslides. 

See table 1 for details of each flood.
4 The World’s Largest Floods—Past and Present

Figure 2. The late-Pleistocene Missoula floods in the Pacific Northwestern United States were some 

of the largest ever to have occurred on Earth. The floods resulted from the repeated breaching of an ice 

dam formed from a lobe of the Cordilleran Ice Sheet that blocked the present-day Clark Fork River and 

created an immense lake known as glacial Lake Missoula. The floods coursed across northern Idaho 

and eastern Washington, ripping up basalt flows and depositing large boulders along their paths. 

(Photograph by Jim O’Connor, U.S. Geological Survey)

Basin-Breach Floods

Filling and spilling of large closed basins can also cause immense floods. Several times during wetter periods of 

the Quaternary Period, hydrologically closed basins have filled with water. Once a rising lake overtops its basin rim, 

spillover can cause rapid erosion, resulting in release of a large volume of water into adjacent drainages. Such was the 

case for the Bonneville flood of North America, which resulted from Pleistocene Lake Bonneville (the ice-age predecessor to Great Salt Lake, Utah) filling the Bonneville Basin, overtopping and eroding unconsolidated sediment that 

formed the drainage divide at Red Rock Pass, and the spilling northward into the Snake River Basin (fig. 3). Nearly 

5,000 km3 (cubic kilometers) of water was released at a peak discharge of about 1 million m3/s during incision of 

about 100 m of the alluvial barrier. There is evidence for similar floods from the many other closed basins in the 

North American Basin and Range Province.

Figure 3. The Lake Bonneville flood of about 14,500 years ago

resulted from nearly 5,000 cubic kilometers of water spilling out of 

the Great Basin and into the Snake River drainage. At a sustained 

peak discharge of about 1 million cubic feet per second, the flow 

filled the 100-meter-deep canyon and overflowed the basalt uplands 

of the Snake River Plain in southern Idaho, stripping soil from a 5-

kilometer-wide swath and carving immense cataracts where flow 

reentered the canyon. (Photograph by Jim O’Connor, U.S. Geological Survey; view looking north)
Floods Related to Volcanism 5

Geologic records also document tremendous 

marine floods into tectonically closed basins. The largest 

known example is the flooding of the Mediterranean 

Basin through a breach developed at the Straits of 

Gibralter—an event now recognized to have caused the 

faunal upheaval used by early geologist Charles Lyell to 

divide the Miocene and Pliocene Epochs. More recently, 

William Ryan and Walter Pitman, of the Lamont Doherty 

Earth Observatory, proposed that the Black Sea Basin 

was flooded about 7,500 years ago by water from the rising Mediterranean Sea when it overtopped and eroded a 

divide at the present-day Bosporus Strait. Ryan and Pitman (1999) further speculated that this event was the biblical Noah's Flood.

A common element of these floods from and into 

hydrographically closed basins is that they all occurred in 

semiarid environments during times of radically changing hydrologic conditions. Enormous terrestrial freshwater floods are generally associated with sustained wetter 

periods that cause basins to fill. Likewise, marine floods 

into closed basins such as the Black Sea are most likely 

during times of rising sea level due to global warming 

and deglaciation. Large closed basins are preferentially 

located in tectonically active regions within the arid subtropical belts. In these regions, long periods of negative 

water balances allow basin development to proceed without continuous overflow and incision of the flanking 

topographic divides, thus creating the potential for large 

water volumes to accumulate before descending over and 

eroding basin rims during rare times of basin filling. 

Likewise, episodes of marine floods into closed basins 

are mainly in semiarid areas, where high evaporation 

rates keep water levels well below sea level, thus providing the necessary elevation difference for cataclysmic 

inflow of marine water.

Floods Related to Volcanism

Volcanism has been directly or indirectly responsible for 5 of the 27 largest global floods (fig. 1). Some of 

the largest volcanic floods resulted from eruptions melting snow and ice, including the largest known historic 

flood caused by volcanism, of about 300,000 m3/s, which 

accompanied a subglacial volcanic eruption at Katla, Iceland, in 1918 (table 1). A 700,000–1,000,000 m3

/s flood 

down Jökulsá á Fjöllum, Iceland, also caused by a subglacial eruption, occurred about 7,000 years ago.

This 1996 jokulhlaup (literally "glacier-burst") in southeastern

Iceland (top) was caused by a volcanic eruption under the 

Vatnajokull glacier (bottom). The glacial meltwater produced by

the eruption poured into a nearby subglacial caldera lake and 

subsequently floated the overlying ice cap sufficiently to quickly 

release about 3.6 cubic kilometers of water. Peak discharge during 

the flood was about 50,000 cubic meters per second. The largest 

jokulhlaup in recorded history, in Katla, Iceland (table 2), had a 

discharge of about 300,000 cubic meters per second at its peak, 

6 times as large. (Photographs by Magnus Tumi Gudmundsson, 

University of Iceland)

Volcanic eruptions have also caused floods by 

means other than direct melting. Debris dams formed 

during volcanic eruptions by lava flows, lahars, pyroclastic flows, and landslides have blocked drainages, allowing lakes to form and breach. A flow of about 260,000 

m3/s coursed down the Toutle River, Washington, about 

2,500 years ago when a landslide associated with an 

eruption of Mount St. Helens blocked a river valley and 

the resulting ancestral Spirit Lake breached cataclysmically. Similar floods would have been likely after the 

1980 Mount St. Helens eruptions if mitigation measures 

had not been undertaken as the modern Spirit Lake rose 

against the 1980 debris avalanche. Large floods from 

breached volcanogenic blockages also resulted from the 
6 The World’s Largest Floods—Past and Present

eruption of Tarawera Volcano, New Zealand, about 700 years ago, and from the Mount Mazama eruption in the 

Oregon Cascade Range about 7,700 years ago. Large historic floods in conjunction with volcanism have been 

reported in southern Mexico, Japan, and Alaska. Additionally, at least two large Quaternary floods on the Colorado River in the Grand Canyon, Arizona, resulted from breaches of lava dams.

Floods from breaches of water-filled calderas and craters have also caused large flows, including a late 

Holocene Epoch flood of about 1 million m3

/s from Aniakchak Volcano in Alaska, a flood 1,800 years ago from Lake 

Taupo, New Zealand, and a late Holocene flood from Newberry Caldera in Oregon.

Floods from Breached Landslide Dams

Failures of landslide dams not directly related to volcanic activity were the cause of 2 of the 27 largest floods 

(table 1). Dam-breach modeling indicates that a flood with a peak discharge of about 540,000 m3

/s, probably the largest flood in recorded history, resulted from breaching of an 1841 rockslide that temporarily blocked the Indus River 

within the western Himalaya, Pakistan. Similarly, there is stratigraphic evidence of a flood of about 220,000 m3

/s 

from breaching of a landslide dam across the Columbia River in western Washington about 500 years ago (fig. 4). 

Figure 4. The Bridge of the Gods landslide slid down from the north wall of the Columbia River Gorge sometime between 1400 and 1465 

A.D., blocking the Columbia River to a depth of 70–80 meters. Breaching of almost the entire thickness of the landslide dam caused a 

flood of about 220,000 cubic meters per second, about six times larger then the largest meteorological flood of the last 150 years. Deposits from the flood form a distinctive marker bed all the way to the Pacific Ocean. The last remnant of the dam was bouldery Cascade 

Rapids, the namesake of the Cascade Range, now drowned in the pool behind the 24-meter-high Bonneville Dam. (Photograph courtesy 

of the U.S. Army Corps of Engineers)
Ice-Jam Floods 7

Landslide dams can form in a wide range of physiographic settings, from high alpine debris avalanches to 

quick-clay failures in wide valley floors. The most common mechanisms triggering dam-forming landslides are 

rainstorms, rapid snowmelt, and earthquakes. Landslide 

dams can be unstable and subject to failure because they 

have no controlled outlet. The vast majority of dam failures and ensuing floods result from overtopping and incision of the blockage, generally beginning soon after 

impounded water first reaches the low point of the blockage.

Despite representing only a small percentage of the 

world's largest floods, breaches of landslide dams are a 

significant hazard. There have been at least six historic 

landslide dam floods with peak discharges greater than 

10,000 m3

/s. Most of these large floods were associated 

with tall blockages of large rivers, including cases where 

breach depths ranged up to 150 m through landslide dams 

that were as high as 250 m. Similar to the case of glacial 

dams, the potential peak discharge through a landslide 

dam increases exponentially with blockage height. Consequently, landscapes that generate large landslides that in 

turn form tall blockages in confined valleys have the 

greatest potential for extreme floods.

Landslide dams can dwarf human-constructed 

dams and therefore produce much larger floods. The largest landslide dam on Earth is the 550 m high Usoi landslide dam in Tajikistan, which created Lake Sarez. The 

dam formed as a result of a large earthquake in 1911.

Usoi Dam in Tajikastan, formed by a landslide in 1911, created

16 cubic-kilometer Lake Sarez, the largest lake in the world

resulting from a landslide. Five million people live in the valleys 

downstream of the dam. Even partial breaching of the dam could 

cause catastrophic flooding. Complete failure of the dam could 

result in the deadliest natural disaster in human history. 

(Photograph courtesy of NASA)

This dam is nearly twice the height of the largest 

constructed dam in the world today, the 300-m-high 

Nurek rockfill dam, also in Tajikistan. The largest 

flood documented from failure of a constructed dam 

is the Teton Dam, Idaho, which failed in 1976 by 

piping (erosion through the dam) and for which the 

peak discharge was about 70,000 m3/s, less than half 

the peak discharge of floods resulting from the 

landslide dam failures listed in table 1.

Ice-Jam Floods

Three of the world's largest 27 recorded flows were 

ice-jam floods on the Lena River, Russia—and this does 

not include the "unprecedented flooding" of May 1998 

for which we have been unable to obtain discharge information. Floods on large rivers from ice jams result from 

"breakup jams," in which dislodged river ice accumulates 

at constrictions or river bends, forcing ponding upstream 

and rapid release of water when the ice dams breach. 

Such was the case in April 1952 on the Missouri River, 

North Dakota, where an eroding ice dam resulted in flow 

increasing from about 2,100 m3/s to more than 14,000 

m3/s in less than 24 hours.

Ice jams, like this one on the Yukon River, Alaska, can cause severe 

flooding when impounded water overflows the stream channel 

upstream and when breakup of the jam suddenly releases water 

downstream. (Photograph courtesy of the Alaska Department of 

Military and Veterans Affairs)

Extreme ice-jam floods are most common in highlatitude, north-flowing continental river systems like the 

Lena River and adjacent large river systems of northern 

Eurasia, and the MacKenzie River of North America. 

Large poleward-flowing rivers are especially susceptible 

to large breakup floods because headwater areas may melt 

before downstream areas, increasing the potential for 

large blockages. 
8 The World’s Largest Floods—Past and Present

Large Meteorological Floods

In the tabulation of Quaternary floods with peak 

discharges greater than 100,000 m3/s, only four floods 

primarily due to rainfall or snowmelt make the list (table 

1)—the floods of 1953, 1963, and 1976 on the Amazon 

River at Obidos, Brazil, and the 1870 flood of 110,000 

m3/s on the Yangtze River, China. The Amazon River, 

draining by far the world's largest basin, with an area 7 

million km2 (square kilometers), including a vast portion 

of the equatorial South American Cordillera, can generate tremendous floods by virtue of its immense size and 

tropical location. The Yangtze (Chang Jiang) River of 

China is also a large basin that receives substantial tropical moisture. 

The paucity of meteorological floods in this list of 

largest Quaternary floods does not indicate lesser significance of meteorologic floods. Indeed, meteorologic 

floods are by far the most common of the types of floods 

in the human experience, affecting parts of the globe 

every year. Such floods can bring good, such as the fertile soils formerly brought to the Nile Delta by annual 

flooding. However, large floods are mostly known for 

their catastrophic loss of life and property, such as 

the floods on the Mississippi River in 1927, when several 

hundred casualties resulted, the Columbia River in 1948, 

when the town of Vanport was destroyed, and the 

Yangtze River in 1931, when nearly 4 million people 

died from flooding and ensuing famine.

The town of Vanport, Oregon, was destroyed in May 1948 when the 

Columbia River flooded due to rapid melting of large snowpacks in 

the Columbia and Snake River Basins. (Photograph from Oregon 

Historical Society [negative OrH: 68809], used by permission)

Records of the largest historic floods from the 

Earth's largest drainage basins (figs. 5 and 6, table 2) 

show that, in general, larger basins produce larger floods.

Variation within this general observation owes partly 

to a pronounced geographic pattern of larger unit 

discharges (defined as peak discharge per unit basin 

area) in the tropics, primarily between latitudes 10o S 

and 30o

 N (fig. 7). The largest floods in large basins 

within the tropics are primarily derived from rainfall 

within areas affected by tropical cyclones or strong 

monsoonal airflow, such as the Brahmaputra, Ganges, 

Yangtze, Mekong, Huangue River Basins, or 

eastward-draining continental basins, such as the 

Amazon and Orinoco River Basins, which intercept 

easterly flows of tropical moisture. The distribution 

of relatively large floods is skewed northward of the 

Equator by the preponderance of land in the northern 

hemisphere, promoting northward migration of 

monsoonal moisture flow driven by orographic lifting 

over large mountain belts, such as the Himalaya in 

south-central Asia.

Several large basins in the tropics do not produce 

relatively large peak discharges. These include the 

Congo, Niger, Chari, and Sao Francisco River Basins, 

which drain large areas of low relief or are isolated 

from zones of major precipitation. Likewise, many of 

the horse-latitude (20o–40o N) and midcontinental drainage basins outside areas of seasonal tropical moisture 

influxes do not produce large flows compared with more 

tropical basins. Examples include the Murray and Darling River Basins in Australia, the Nile River and Zambezi River Basins in Africa, and the Colorado and 

Mississippi River Basins of North America.

Northward of 40o N, snowmelt and ice jams are 

important contributors to peak discharges from large 

basins, forming a group of rivers with flood discharges 

greater than the apparent latitudinal limits of flood flows 

derived primarily from rainfall (fig. 7). Exceptional discharges on the Lena, Yenisey, and Yukon Rivers were 

augmented by ice jams, but relatively large flows on rivers such as the Columbia and Dnieper Rivers indicate the 

importance of melting snow to peak flows, especially in 

midlatitude basins with substantial relief. With the 

present configuration of continents, there are no southern 

hemisphere river basins greater than 500,000 km2

 with 

peak discharges substantially affected by snowmelt.

Floods, Landscapes, and Hazards

One observation evident from consideration of the 

world’s largest floods is that the incidence of floods 

caused by different processes changes through time. 
Floods, Landscapes, and Hazards 9

Figure 5. This map shows rivers with drainage basins larger than 500,000 square kilometers. Map numbers are keyed to table 2.

Figure 6. In general, larger river basins produce larger floods, 

but larger unit discharges in the moist tropics can result in floods 

of disproportionately large size. Numbers refer to basin numbers 

in figure 5 and table 2.

Most of the largest documented floods in the past 

100,000 years resulted from the failures of natural dams, 

but conditions that caused some of the largest of 

these natural dams, such as the large ice-dam 

failures at the margins of continental ice sheets, are 

now absent. Consequently, earth history contains 

"flood epochs"—times when climate and topography 

combine to produce higher-than-typical frequencies 

of large floods. To produce floods with discharges 

greater than about 1 million m3/s, times of advanced 

continental ice sheets and rapidly changing global 

water balances are required. In many locations, these 

outsized floods from previous flood epochs were 

dominant forces in establishing regional drainage 

networks and landscape patterns that persisted into 

times of fewer extreme floods.

Other geologically controlled cataclysmic floods 

are probably more evenly distributed in time, at least at 

time scales of hundreds to thousands of years. Consequently, the future likelihood and magnitude of such 

events can be more directly guided by analysis of past 

events. Within active volcanic provinces, the likelihood 

of large volcanic eruptions and the consequent floodgeneration processes probably does not change significantly over hundreds or even thousands of years. Similarly, the frequency of large valley-blocking landslides 

probably remains relatively constant over such time 

scales.
Table 2. Largest meteorologic floods from river basins larger than about 500,000 square kilometers.

[Data from Rodier and Roche (1984) except as noted. River and station locations shown on figure 5. Station area: 103km2, thousand square kilometers. Station latitude 

and longitude: N, north; S, south; E, east; W, west. Peak discharge: m3

/s, cubic meters per second]

Basin 

number River basina Country

Basin area 

(103 km2)

b Station

Station area

(103 km2)

Station 

latitude 

(degrees)

Station 

longitude 

(degrees)

Peak 

discharge

(m3

/s) Date Flood type

1 Amazon Brazil 5,854 Obidos 4,640 1.9S 55.5W 370,000 June 1953 Rainfall

2 Nile Egypt 3,826 Aswan 1,500 24.1N 32.9E 13,200 Sept. 25, 1878 Rainfall

3 Congo Zaire 3,699 Brazzaville B. 3,475 4.3S 15.4E 76,900 Dec. 27, 1961 Rainfall

4 Mississippic USA 3,203 Arkansas City 2,928 33.6N 91.2W 70,000 May 1927 Rainfall

5 Amur Russia 2,903 Komsomolsk 1,730 50.6N 138.1E 38,900 Sept. 20, 1959 Rainfall

6 Parana Argentina 2,661 Corrientes 1,950 27.5S 58.9W 43,070 June 5, 1905 Rainfall

7 Yenisey Russia 2,582 Yeniseysk 1,400 58.5N 92.1E 57,400 May 18, 1937 Snowmelt

8 Ob-Irtysh Russia 2,570 Salekhard 2,430 66.6N 66.5E 44,800 Aug. 10, 1979 Snowmelt

9 Lena Russia 2,418 Kasur 2,430 70.7N 127.7E 189,000 June 8, 1967 Snowmelt/Ice 

Jam

10 Niger Niger 2,240 Lokoja 1,080 7.8N 6.8E 27,140 Feb. 1, 1970 Rainfall

11 Zambezi Mozambique 1,989 Tete 940 16.2S 33.6E 17,000 May 11, 1905 Rainfall

12 Yangtze China 1,794 Yichang 1,010 30.7N 111.2E 110,000 July 20, 1870 Rainfall

13 Mackenzie Canada 1,713 Norman Wells 1,570 65.3N 126.9W 30,300 May 25, 1975 Snowmelt

14 Chari Chad 1,572 N'Djamena 600 12.1N 15.0E 5,160 Nov. 9, 1961 Rainfall

15 Volga Russia 1,463 Volgograd 1,350 48.5N 44.7E 51,900 May 27, 1926 Snowmelt

16 St. Lawrence Canada 1,267 La Salle 960 45.4N 73.6W 14,870 May 13, 1943 Snowmelt

17 Indus Pakistan 1,143 Kotri 945 25.3N 68.3E 33,280 1976 Rain/Snowmelt

18 Syr Darya Kazakhstan 1,070 Tyumen’-Aryk 219 44.1N 67.0E 2,730 June 30, 1934 Rain/Snowmelt

19 Orinoco Venezuela 1,039 Puente 

Angostura

836 8.1N 64.4W 98,120 Mar. 6, 1905 Rainfall

20 Murray Australia 1,032 Morgan 1,000 34.0S 139.7E 3,940 Sept. 5, 1956 Rainfall

21 Ganges Bangladesh 976 Hardings 

Bridge

950 23.1N 89.0E 74,060 Aug. 21, 1973 Rain/Snowmelt

22 Shatt al Arab Iraq 967 Hit(Euphrates) 264 34.0N 42.8E 7,366 May 13, 1969 Rain/Snowmelt

23 Orange South Africa 944 Buchuberg 343 29.0S 22.2E 16,230 1843 Rainfall

24 Huanghe China 894 Shanxian 688 34.8N 111.2E 36,000 Jan. 17, 1905 Rainfall

25 Yukon USA 852 Pilot Station 831 61.9N 162.9W 30,300 May 27, 1991 Snowmelt

26 Senegal Senegal 847 Bakel 218 14.9N 12.5W 9,340 Sept. 15, 1906 Rainfall

27 Coloradoc USA 808 Yuma 629 32.7N 114.6W 7,080 Jan. 22, 1916 Rainfall

28 Rio Grandec USA 805 Roma 431 26.4N 99.0W 17,850 1865 Rain/Snowmelt

29 Danube Romania 788 Orsova 575 44.7N 22.4E 15,900 April 17, 1895 Snowmelt

30 Mekong Vietnam 774 Kratie 646 12.5N 106.0E 66,700 Sept. 3, 1939 Rainfall

31 Tocantins Brazil 769 Itupiranga 728 5.1S 49.4W 38,780 April 2, 1974 Rainfall

32 Columbiac USA 724 The Dalles 614 45.6N 121.2W 35,100 June 6, 1894 Snowmelt

33 Darling Australia 650 Menindee 570 32.4S 142.5E 2,840 June 1890 Rainfall

34 Brahmaputrad Bangladesh 650 Bahadurabad 636 25.2N 89.7E 81,000 Aug. 6, 1974 Rain/Snowmelt

35 São Francisco Brazil 615 Traipu 623 9.6S 37.0W 15,890 April 1, 1960 Rainfall

36 Amu Darya Kazakhstan 612 Chatly 450 42.3N 59.7E 6,900 July 27, 1958 Rain/Snowmelt

37 Dnieper Ukraine 509 Kiev 328 50.5N 30.5E 23,100 May 2, 1931 Snowmelt

10 The World’s Largest Floods—Past and Present

a

Basins larger than 500,000 square kilometers for which reliable data were not available include the Nelson River in North America; 

the Jubba, Irharhar, Araye, Tafassasset and Qattar Rivers in Africa; and the Kolyma and Tarim Rivers in Asia.

bBasin areas from Vörösmarty et al. (2000).

c

Station and discharge data from U.S. Geological Survey National Water Information System (http://water.usgs.gov/nwis).

d

Station area and drainage basin data from Global Runoff Data Centre in the Federal Institute of Hydrology, Germany 

(http://www.bafg.de/grdc.htm).
Floods, Landscapes, and Hazards 11

Figure 7. Nearly all of the largest floods 

caused by rainfall have occurred in basins 

south of latitude 40 degrees N. North of 

that, snowmelt- and ice-jam-related floods 

have predominated. Data from table 2.

Exceptionally large floods are 

not evenly distributed around the 

globe. The largest Quaternary floods 

from natural dam failures and closed 

basin spillovers have been in the midlatitudes, where advancing ice sheets 

blocked large continental drainage 

systems and where closed basins in 

arid or semiarid regions filled and 

then spilled during wetter periods of 

earth history. The largest recorded 

meteorological floods have been in 

tropical regions, especially where 

monsoon moisture falling on large 

and high-relief drainage basins produces immense volumes of runoff.

This broad framework for the 

temporal and spatial distribution of 

floods is but a launching point for 

ongoing USGS flood research. 

Together with many cooperating 

State, local, and Federal agencies, 

academic institutions, and international partners, USGS studies 

focused on floods are taking many forms. These activities include developing new ways to measure and monitor 

floods and to map flood hazards, investigating the complex relations between floods and persistent climatic patterns 

such as the El Niño Southern Oscillation and the Pacific Decadal Oscillation, and understanding the role of flood processes in forming and maintaining landscapes and ecologic systems. All of these activities have the goal of providing 

high-quality scientific information that can be used to make informed decisions regarding the management of floods 

and their benefits and hazards throughout the world. 
12 The World’s Largest Floods—Past and Present

Selected References 

Baker, V.R., Kochel, R.C., and Patton, P.C., eds., 1988, 

Flood Geomorphology: New York, Wiley, 503 p.

Baker, V.R., Benito, G., and Rudoy, A.N., 1993. Paleohydrology of late Pleistocene superflooding, Altay 

Mountains, Siberia: Science, 259, p. 348–350.

Costa, J.E., 1987, A comparison of the largest rainfall-runoff 

floods in the United States with those of the People’s 

Republic of China and the world: Journal of Hydrology, 

v. 96, p. 101–115.

House, P.K., Webb, R.H., Baker, V.R., and Levish, D.R., eds., 

2001, Ancient floods, modern hazards—Principles and 

application of paleoflood hydrology: American 

Geophysical Union Water Science and Application 

Series, no. 5, 385 p.

Hoyt, W.G., and Langbein, W.B., 1955, Floods: Princeton, 

New Jersey, Princeton University Press, 469 p.

Lord, M.L., and Kehew, A.E., 1987, Sedimentology and 

paleohydrology of glacial-lake outburst deposits in 

southeastern Saskatchewan and northwestern North 

Dakota: Geological Society of America Bulletin v. 99, 

p. 663–673.

Matsch, C.L., 1983, River Warren, the southern outlet of 

Glacial Lake Agassiz, in Teller, J.T., and Lee, Clayton, 

Glacial Lake Agassiz: Geological Association of Canada 

Special Paper 26, p. 231–244.

Mayo, L.R., 1989, Advance of Hubbard Glacier and 1986 

outburst of Russell Fiord, Alaska, U.S.A.: Annals of 

Glaciology, v. 13, p. 189–194.

Miller, E.W., and Miller, R.M., 2000, Natural disasters— 

Floods, A reference handbook: Santa Barbara, California, 

ABC-CLIO, 286 p.

O'Connor, J.E., 1993, Hydrology, hydraulics, and 

geomorphology of the Bonneville flood: Geological 

Society of America Special Paper 274, 83 p.

O'Connor, J.E., and Baker, V.R., 1992, Magnitudes and 

implications of peak discharges from Glacial Lake 

Missoula: Geological Society of America Bulletin, v. 104, 

p. 267–279.

O’Connor, J.E., Grant, G.E., and Costa, J.E., 2002, The 

geology and geography of floods, in House, P.K., Webb, 

R.H., Baker, V.R., and Levish, D.R., eds., Ancient floods, 

modern hazards: principles and application of paleoflood 

hydrology: American Geophysical Union Water Science 

and Application Series, no. 5, p. 359–385.

O'Connor, J.E., Pierson, T.C., Turner, D., Atwater, B.F., and 

Pringle, P.T., 1996, An exceptionally large Columbia 

River flood between 500 and 600 years ago—Breaching 

of the Bridge-of-the-Gods landslide?, Geological Society 

of America Program with Abstracts, v. 28, no. 7, p. 97.

Rodier, J.A., and Roche, M., 1984, World catalogue of 

maximum observed floods: International Association of 

Hydrologic Sciences Publication No. 143, 354 p.

Ryan, W., and Pitman, W., 1999, Noah’s flood—The new 

scientific discoveries about the event that changed 

history: New York, Simon and Schuster, 310 p.

Rudoy, A., 1998, Mountain ice-dammed lakes of southern 

Siberia and their influence on the development and 

regime of the intracontinental runoff systems of North 

Asia in the late Pleistocene, in Benito, G., Baker, V.R., 

and Gregory, K.J., eds., Paleohydrology and 

Environmental Change: John Wiley and Sons, p. 215–

234.

Scott, W.E., 1989, Volcanic and related hazards, in Volcanic 

hazards—Short course in geology—Volume 1: 

Washington, D.C., American Geophysical Union, 

p. 9–50.

Shroder, J.F. Jr., Cornwell, K., and Khan, M.S., 1991, 

Catastrophic breakout floods in the western Himalaya, 

Pakistan: Geological Society of America Program with 

Abstracts, v. 23, no, 5, p. 87.

Smith, D.G. and Fisher, T.G., 1993. Glacial Lake Agassiz— 

The northwest outlet and paleoflood: Geology v. 21, 

no. 1, p. 9–12.

Teller J.T., and Thorliefson, L.H., 1987, Catastrophic flooding 

into the Great Lakes from Lake Agassiz, in Majer, L. and 

Nash, D. eds.,. Catastrophic flooding: London, Allen & 

Unwin, p. 121–138.

Thorson, R.M., 1989, Late Quaternary paleofloods along the 

Porcupine River, Alaska—Implication for regional 

correlation, in Carter, L.D., Hamilton, T.D., and 

Galloway, J.P., eds., Late Cenozoic history of the interior 

basins of Alaska and the Yukon: U.S. Geological Survey 

Circular 1026, p. 51–54.

Tomasson, H., 1996, The jokulhlaup from Katla in 1918: 

Annals of Glaciology, v. 22, p. 249–254.

Vaughn, D., and Ash, D.W., 1983, Paleohydrology and 

geomorphology of selected reaches of the upper Wabash 

River, Indiana: Geological Society of America Program 

with Abstracts, v. 15, no. 6, p. 711.

Vörösmarty, C.J., Fekete, B.M., Meybeck, M., and Lammers, 

R.B., 2000, Geomorphometric attributes of the global 

system of rivers at 30-minute spatial resolution: Journal of 

Hydrology v. 237, p. 17–39.

Waitt, R.B., 2002, Great Holocene floods along Jökulsá á 

Fjöllum, North Iceland, in Martini, I.P., Baker, V.R., and 

Garzón, G., eds., Flood and megaflood processes— 

Recent and ancient examples: International Association of 

Sedimentologists, Special Publication 32, p. 37–52.

Walder, J.S., and O’Connor, J.E., 1997, Methods for predicting 

peak discharge of floods caused by failure of natural and 

constructed earthen dams: Water Resources Research, 

v. 33, p. 2337–2348.
Selected References 13

Waythomas, C.F., Walder, J.S., McGimsey, R.G., and Neal, 

C.A., 1996, A catastrophic flood caused by drainage of a 

caldera lake at Aniakchak Volcano, Alaska, and 

implications of volcanic hazards assessment: Geological 

Society of America Bulletin, v. 108, no. 7, p. 861–871.

For More Information: 

USGS Flood Information

http://water.usgs.gov/osw/programs/floods.html

USGS Fact Sheet: Significant Floods in the United States 

During the 20th Century

http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.024-

00.html

USGS Circular: Large Floods in the United States—Where 

They Happen and Why

http://pubs.water.usgs.gov/circ1245

USGS Water Watch

http://water.usgs.gov/waterwatch/

Dartmouth University Flood Observatory

http://www.dartmouth.edu/~floods/

EarthSatTM flood maps 

http://www.earthsat.com/wx/flooding/

National Weather Service: Significant River Flood Outlook

http://www.hpc.ncep.noaa.gov/nationalfloodoutlook/

Federal Emergency Management Agency (FEMA) Flood 

Hazard Mapping

http://www.fema.gov/mit/tsd/fq_genhm.htm

Societal Aspects of Weather: Floods

http://sciencepolicy.colorado.edu/socasp/floods.html