Most Dangerous Rivers in the World, Ranked by Their Deadliest Floods

Measured by the death toll of their worst recorded flood, the most dangerous rivers in the world are China's Yellow River, whose 1887 flood killed at least 930,000 people and possibly 2 million; the Yangtze, whose 1931 floods with the Huai killed somewhere between 422,000 and 4 million; and the Ru River in the Huai basin, where the 1975 Banqiao Dam failure killed between 26,000 and 240,000, according to Wikipedia's List of deadliest floods and the articles on each event, as they stood in October 2026. Below those three, the ranking runs from Libya's Wadi Derna to Nepal's Trishuli, and almost every entry tells the same story: a river held back by dikes or dams that failed, or were overwhelmed, when the water was highest.

How the List of Deadliest Floods turns "dangerous" into a number

"Dangerous" can mean crocodiles, rapids, pollution or disease, and none of those is counted consistently from one country to the next. Flood deaths are. The ranking below takes Wikipedia's List of deadliest floods, keeps only floods that came down one named river and have their own event article, and scores each river once, by its single deadliest event. Where the death toll is a range, the river's place is set by the lower estimate in that event's article.

That rule leaves several large entries out. Storm surges such as the 1970 Bhola cyclone and the medieval North Sea floods came from the sea. The 1949 Guatemala floods (up to 40,000 dead) and the 1954 Great Iran Flood (2,000 to 10,000) were regional rainstorms across many rivers and lakes. The 27,000 to 1.5 million listed for Bangladesh in 1974 counts the famine that followed that year's floods, and the 1939 Tianjin flood (20,000) and the 1705 Po Valley flood (15,000) are uncited lines with no article behind them.

Two cautions apply. Older Chinese tolls include people who died of famine and disease after the water receded, so they are not directly comparable with a modern count of drownings. And several rivers appear here because of a dam or levee failure rather than the river's natural behaviour, which is itself part of the danger: a river that has been confined for decades can release far more water at once when the barrier goes.

10 to 8: the Trishuli in 2026, the Machchhu in 1979 and the Vajont in 1963

10. Trishuli River, 2026 — at least 1,497 deaths. On the morning of 26 August 2026, a rock-ice avalanche from the Lirung massif in the Langtang Himal turned into a long-runout debris flow, and flash floods tore down the Lhende Khola and the Trishuli. They destroyed the Gyirong Port crossing on the China–Nepal border, which had carried 30 per cent of Nepal–China trade, and struck dozens of settlements along 72 km of the Trishuli. By late September Nepal counted 1,454 dead and 4,718 missing, and Tibet 43 dead and 519 missing, so this river's place is likely to rise. Some bodies were carried 240 km into India.

9. Machchhu River, 1979 — 1,800 to 25,000 deaths. On 11 August 1979 heavy rain sent 16,307 m³ per second into the Machchhu-2 dam in Gujarat, three times what it was designed to pass, and its earthen embankments gave way. Within 20 minutes water 3.7 to 9.1 m deep was running through Morbi, 5 km downstream. The Guinness Book of Records listed it as the worst dam burst until China declassified the Banqiao files in 2005. When the dam was rebuilt, its spillway capacity was increased fourfold.

8. Vajont, into the Piave, 1963 — 1,917 to 2,500 deaths. Here the dam held, which is what makes the Vajont unusual. On 9 October 1963, during the first filling of the reservoir 100 km north of Venice, the flank of Monte Toc slid into the lake. About 50 million cubic metres of water went over the 262 m dam in a wave 250 m high and poured down the Vajont gorge into the Piave valley, destroying Longarone, Pirago, Rivalta, Villanova and Faè. The operators had been warned that the slope was unstable. Just outside this top ten is the 1998 monsoon flood of the Brahmaputra, Ganges and Meghna, which killed 1,050 people in Bangladesh and affected 30 million.

7 and 6: the Indus in 2010 and the Little Conemaugh in 1889

7. Indus River, 2010 — 1,985 deaths. Heavy monsoon rain from late July 2010 swelled the Indus basin until roughly one-fifth of Pakistan's land area was affected. More than 90 per cent of the deaths were in Khyber Pakhtunkhwa, though the flooding also reached Sindh, Punjab and Balochistan. Government figures put the number of people directly affected at about 20 million, and the total economic impact may have reached US$43 billion.

6. Little Conemaugh River, 1889 — 2,208 deaths. The Johnstown Flood was not caused by the river rising so much as by the South Fork Dam failing on 31 May 1889, 23 km (14 mi) upstream of Johnstown, Pennsylvania. It released 14.55 million cubic metres of water, briefly flowing as fast as the average Mississippi. By loss of life it remains by far the worst flash flood in United States history, and the legal battles that followed helped shift American tort law towards strict liability. The relief effort was one of the first major operations of the American Red Cross, led by Clara Barton with 50 volunteers, and help arrived from 18 foreign countries; the site has been the Johnstown Flood National Memorial since 1964.

5 and 4: Wadi Derna in 2023 and the Mandakini in 2013

5. Wadi Derna, 2023 — at least 5,923 deaths, possibly far more. Most of the year Wadi Derna is a dry riverbed in eastern Libya. When Storm Daniel made landfall in Libya on 10 September 2023, the Derna and Mansour dams above the city, clay-filled embankments built by a Yugoslav firm between 1973 and 1977, collapsed in the night of 10–11 September. An estimated 30 million cubic metres of water tore through Derna, overflowing the wadi by 50 m on each side and splitting the city in two. Libya confirmed 5,923 deaths with thousands missing; the mayor feared 18,000 to 20,000, and a 2026 study cited by the List of deadliest floods counts more than 11,498. Researchers at Yale called it the deadliest single flood recorded in Africa; it sits fifth here only because its confirmed count is slightly lower than the Mandakini’s.

4. Mandakini and the upper Ganges, 2013 — 6,054 deaths. In June 2013 a low-pressure system from the Bay of Bengal met a western disturbance over Uttarakhand, and torrential rain melted ice on the Chorabari Glacier above Kedarnath. The meltwater flooded Chorabari Lake and then Kedarnath, sending a surge down the Mandakini, an 81 km tributary of the Alaknanda and so of the Ganges. Gaurikund and Ram Bada were obliterated, and about 300,000 pilgrims and tourists were trapped in the valleys leading to three of the four Chota Char Dham shrines. More than 89 per cent of the deaths were in Uttarakhand.

3: the Ru River and the 1975 Banqiao Dam failure

The Banqiao Dam stands on the Ru, a tributary of the Hong River in Zhumadian, Henan, within the Huai basin. In August 1975, after Typhoon Nina made landfall, rain near the storm's centre exceeded the normal yearly rainfall of 1,060 mm in a single day, far beyond the 300 mm a day the dam had been designed for. Banqiao and 61 other dams across Henan collapsed, flooding 12,000 km² where 10.15 million people lived and destroying between 5 and 6.8 million houses.

Estimates of the dead range from 26,000 to 240,000, a spread that reflects how long the disaster stayed hidden. Many of the dams in the region were built during the Great Leap Forward, and the details only emerged in the 1990s with the book The Great Floods in China's History, prefaced by the former Minister of Water Resources Qian Zhengying. Banqiao was later rebuilt.

2 and 1: the Yangtze in 1931 and the Yellow River, "China's Sorrow"

2. Yangtze, with the Huai, 1931 — 422,000 to 4 million deaths. After years of drought, a harsh winter and a spring of melting snow, the summer of 1931 brought nine cyclones in July alone, against an average of two a year. Floods covered about 180,000 km², roughly England plus half of Scotland. At Hankou in Wuhan the water peaked on 19 August at 16 m above average, and a dike failure on 27 July had already left about 782,000 people homeless in the city. On 25 August the Grand Canal dikes near Lake Gaoyou gave way, drowning 18,000 people in Gaoyou County alone. A University of Nanking survey led by John Lossing Buck counted 150,000 drowned and judged that drowning accounted for less than a quarter of all deaths in the first 100 days.

1. Yellow River, 1887 — 930,000 to 2 million deaths. The Yellow River, 5,464 km long, carries so much loess silt that its bed has risen over the centuries, and farmers kept raising the dikes to match. Around 28 September 1887, after days of heavy rain, the river broke through near Huayuankou outside Zhengzhou in Henan. Water spread across about 130,000 km² of the North China Plain, two million people lost their homes, and disease and hunger killed about as many as the flood itself. It is the deadliest flood in Chinese history.

The Yellow River also has a second entry near the top of the list of deadliest floods. In June 1938 Nationalist commanders deliberately breached the same Huayuankou dikes to slow the Japanese advance; between 30,000 and 89,000 civilians drowned, and 400,000 to 500,000 died from drowning, famine and plague. One estimate counts 1,593 floods and 26 noticeable changes of course between 595 BC and 1946, which is why the river has long been called a blessing and a curse. For the long story of those course changes, read our guide to the Yellow River as China's Sorrow, and for the weather and land-use factors that turn rain into disasters like these, see what causes floods.