You may have heard the term flash flood before, but perhaps you’re not sure what exactly it means or how it works. In this article, we’ll explain what flash flooding actually is, why it happens, and when you’re most likely to experience it. We’ll also talk about how to stay safe during a flash flood event and how to get the emergency services you need if one strikes unexpectedly.
What is Flash Flooding?
Flash flooding is a dangerous weather phenomenon that can happen with little to no warning. Flash floods can occur when there is heavy rain, when a dam or levee breaks, or when snow melts too quickly. When flash flooding happens, water can rise quickly and overwhelm people and vehicles. This can lead to serious injuries or even death. If you live in an area that is prone to flash flooding, it is important to be prepared. Make sure you know where to go if you need to evacuate, and have a plan for what to do if your home or business is flooded.
You should also have emergency supplies on hand such as a battery-powered radio, food and drinking water, first aid kit, flashlight (with extra batteries), cash, medications, pet food and leashes. These things will help you stay safe while the waters recede.
What Causes Flash Floods?
Flash floods can be caused by a variety of things, but they all have one thing in common: too much water. Heavy rains, melting snow, and dam or levee failures can all lead to flash flooding. When the ground is already saturated with water, it doesn’t take much for floodwaters to rise quickly and overwhelm an area. Just six inches of fast-moving water can knock a person down, and two feet of water can sweep a car off the road. Flash floods can happen with little or no warning, which is why they’re so dangerous. If you’re caught in a flash flood, get to higher ground immediately and stay there until the danger has passed.
The Signs of a Flash Flood
Do you know what to do if a flash flood hits your area? Flash floods are one of the most underrated weather phenomena – but they can be incredibly dangerous. Here are some signs that a flash flood is about to happen:
- A sudden, intense rainfall
- Thunder and/or lightning
- Rapidly rising water levels
- Large amounts of debris in the water
- Water moving at high speeds
- Rising water levels in rivers or streams
- Flooding in normally dry areas
- Dam failure
- Abnormally strong currents
- Loss of power for more than an hour
How to Survive a Flash Flood
Flash floods can occur anywhere there is heavy rainfall, but they are most common in areas with low-lying ground, such as river valleys or near mountains.
How can you survive a flash flood? If you are caught in a flash flood, the best thing to do is to move to higher ground immediately. Do not try to drive through flooded roads, as this can be extremely dangerous. If you are stranded on a road that is flooding, abandon your vehicle and seek higher ground on foot. Remember to stay away from power lines and electrical equipment, as these can pose a serious danger.
A History of Flash Floods
Flash floods have been around for centuries, and they’re one of the most dangerous weather phenomena out there. Despite this, many people don’t know what a flash flood is or how to stay safe during one.
This list of notable flash floods summarizes the most widely reported events.
Information provided by WikiPedia
| Date | Fatalities | Cause | Description |
|---|---|---|---|
| 11 March 1864 | 240 | dam failure | Great Sheffield Flood, Sheffield, England |
| 31 May 1889 | 2200 | dam failure | Johnstown Flood Johnstown, Pennsylvania, U.S. |
| 14 June 1903 | 247 | thunderstorm | Heppner Flood of 1903, Oregon, U.S. Second-deadliest flash flood in the United States; killed almost a quarter of the town’s residents. |
| 11 July 1912 | 8 | thunderstorm | Mazuma, Nevada, Postmistress among the dead. Relief efforts included a fund set up by William Randolph Hearst. |
| 15 January 1919 | 21 | dam failure | Great Molasses Flood, Boston, U.S. A 8-to-15-foot (2.4 to 4.6 m) wall of molasses from a collapsed distillation storage tank moved through the streets at 35 miles per hour (56 km/h) killing 21, injuring 150 |
| 19 February 1938 | 21 | thunderstorm | Kopuawhara flash flood of 1938, Mahia Peninsula, New Zealand: a temporary camp for rail workers next to a river was hit by a 5-metre (16 ft) high wall of water[1] already swollen by heavy rain associated with Typhoon Haikui.[2] |
| 15 August 1952 | 34 | heavy rain | Lynmouth Flood, England |
| 31 January 1953 | 2394 | heavy storm | North Sea flood of 1953, The Netherlands, Belgium, England, Scotland, a combination of a high spring tide and a severe European windstorm over the North Sea caused a storm tide. As a result, the Dutch Delta Works were authorized, an elaborate project to enable emergency closing of the mouths of most estuaries, to prevent flood surges upriver. |
| 17 June 1965 | 0 | heavy rain | 1965 Philmont Scout Ranch flash flood, Philmont Scout Ranch, New Mexico |
| 25 November 1967 | 464 | heavy rain | 115 to 129 millimetres (4.5 to 5.1 in) rain in 5 hours at up to 30 millimetres (1.2 in) per hour near Lisbon, Portugal[3] |
| 4 January 1971 | 32 | monsoon | Kuala Lumpur floods, Malaysia |
| 9 June 1972 | 238 | dam failure | Black Hills flood, South Dakota, U.S., 15 inches (38 cm) in 6 hours |
| 31 July 1976 | 143 | thunderstorm | Big Thompson River flood, Colorado, U.S. |
| 11 August 1979 | 1800–25,000 | dam failure | Machchu-2 dam failed due to heavy upstream rain, washed out the town of Morbi and nearby villages of Gujarat, India. Estimated deaths ranged from 1800 to 25,000 people. Considered worst flash flood of history. |
| 24 July 1982 | 299 | heavy rain | maximum 187 millimetres (7.4 in) rainfall per an hour in Nagayo, Nagasaki, floods, landslides, and bridge, house, buildings collapses occur simultaneously in the suburbs of Nagasaki, Kyushu Island, Japan[4] |
| 19 November 1983 | 10 | heavy rain | maximum rate of 24 millimetres (0.94 in) in 30 minutes near Lisbon, Portugal, with similar intensity of 1967 event; much lower fatalities due to lessons learned[3] |
| 14 June 1990 | 26 | heavy rain | Shadyside, Ohio, U.S.[5] |
| 16 June 1990 | 4 | thunderstorm | Duck Creek Floods of 1990 near Davenport, Iowa, U.S.[6] |
| 12 August 1997 | 11 | thunderstorm | Antelope Canyon, Arizona, U.S. |
| 20 July 1998 | 63 | heavy rain | Jarovnice, Slovakia. Combination of heavy rain and collapse of dam formed by debris caused flood wave inundated the unprotected Romani settlement. |
| 18 October 1998 | 31 | heavy rain | San Marcos, Texas, U.S., rains totaling from 15 to 30 inches (380 to 760 mm)[7] |
| 11 September 2000 | 10 | heavy rain | According to Japan Meteorological Agency official confirmed report, a 100 millimetres (3.9 in) to 114 millimetres (4.5 in) principation per a single hour, total 428 millimetres (16.9 in) to 492 millimetres (19.4 in) principation per twelve hours, following flash flooded in Nagoya and surrounding area, another 150 persons were wounded, Japanese government official confirmed report.[8] |
| 30 August 2003 | 6 | heavy rain | Jacobs Creek Flood, Kansas Turnpike near Emporia, Kansas, U.S. |
| 16 August 2004 | 0 | heavy rain | Boscastle flood, Cornwall, England |
| 6 August 2006 | 350 | heavy rain | eastern Ethiopia, tens of thousands displaced[9][10] |
| 13 August 2006 | 125 | heavy rain | southern Ethiopia, hundreds of thousands displaced[9] |
| 3 July 2007 | 64 | Sudan floods | |
| 2 November 2007 | 0 | heavy rain | Mount Rainier National Park, Washington, U.S.[11] |
| 12 June 2008 | 0 | thunderstorm | The 12–13 June 2008 floods around Duck Creek in Davenport, Iowa, U.S.[12] |
| 4 August 2009 | 0 | thunderstorm | The 2009 Kentuckiana Flash Flood resulted from 3 to 6 inches (76 to 152 mm) of rain falling in less than an hour near Louisville, Kentucky, U.S. |
| 9 September 2009 | 31 | heavy rain | Turkish flash floods. |
| 19 September 2009 | 10 | heavy rain | 2009 Southeastern United States floods included flash flooding around Atlanta, Georgia, U.S.[13] |
| 26 September 2009 | 100 | tropical storm | Metro Manila, primarily Marikina, Taguig, and Pasig; and several municipalities in the provinces of Rizal, Bulacan, and Laguna, taking more than a hundred lives and leaving thousands of affected residents homeless. It also submerged several municipalities under feet deep of water for several weeks. It was caused by Typhoon Ketsana. |
| 1 October 2009 | 37 | heavy rain | Giampilieri, Messina, Sicily. See Also 2009 Messina floods and mudslides |
| 10 October 2009 | 10–13 October in Northern Luzon causing major landslides in the Cordillera Mountains (Philippines), and submerging 80% of the Province of Pangasinan. | ||
| October 2009 | 0 | heavy rain | In late October, a rainy nor’easter caused several flash floods in Southeast Virginia (U.S.) and injured over 100 people. |
| 25 November 2009 | 122 | heavy rain | More than 122 people died in flash floods that swept away highways and neighborhoods in the city of Jeddah, Saudi Arabia, which was caused by heavy rains.[14] |
| 20 February 2010 | 42 | heavy rain | 2010 Madeira floods and mudslides: 108 to 165 millimetres (4.3 to 6.5 in) of rain fell in 5 hours, much more than the monthly February average of 88 millimetres (3.5 in). 51 people died, 250 were injured, and at least eight people went missing. |
| April 2010 | April–May: The great Nashville, Tennessee, U.S., flood. Water in the Cumberland river rose, flooding downtown Nashville and surrounding areas. | ||
| 11 June 2010 | 20 | heavy rain | The Little Missouri River rose over 20 feet in only a few hours, 2010 Arkansas floods |
| 24 July 2010 | 0 | dam failure | Delhi Dam on Iowa’s Maquoketa River breached after 9 inches (230 mm) of rainfall. 8,000 people evacuated and 15 ft. chunks of highway broke off and swept down river. Contributed to flooding the Mississippi River in Davenport, Iowa. |
| July 2010 | 1400 | monsoon | Mid–July till mid-August, Pakistan’s three provinces were badly affected during the monsoon rains when dams, rivers and lakes overflowed killing at least 1400 people and affecting 3.5 million people. |
| 6 August 2010 | 180 | cloud burst | Leh, India. More than 180 people were reported to have died with 400 missing and 300 injured due to flash floods, caused probably due to cloud burst. Injured and stranded public have been airlifted by Indian army.[15] |
| 4 October 2010 | 7 | chemical plant accident | flood caused by the Ajka alumina plant accident in western Hungary[16] A dam wall collapsed, freeing about one million cubic metres (35 million cubic feet) of highly alkaline liquid waste, called red mud, from the Ajkai Timföldgyár alumina plant in Ajka,[17][18] Veszprém County. The mud was released as a 1–2 m (3–7 ft) wave, flooding several nearby localities, including the village of Kolontár and the town of Devecser. The flood killed seven persons and the high pH (~13) of the sludge burned several hundred people and devastated more than 40 km2 of ground in the basin of the Danube river. |
| 18 October 2010 | 0 | heavy rain | St. Lucia, West Indies:[19] The flood displaced about 500 people and received immediate assistance from local government and international organizations. No fatalities or injuries were reported.[20] |
| 27 – 28 July 2011 | 1 | heavy rain | Dubuque County, Iowa – Jo Daviess County, Illinois, United States.[21] |
| 11 January 2011 | 35 | heavy rain | 2010–2011 Queensland floods, Australia[22] |
| 7 July 2012 | 172 | heavy rain | 2012 Russian floods Krasnodarsky krai, Russia[23] |
| 7 August 2012 | 89 | monsoon | 2012 Philippine floods Monsoon enhanced by Typhoon Haikui brought torrential rain and floods to Metro Manila and nearby provinces[24] |
| 1 April 2013 | 101 | rain storm | 2013 Argentina floods For five hours there was extremely heavy rainfall on northeastern section of Buenos Aires Province, Argentina, resulting in several flash floods that claimed the lives of at least 101 people. Greater La Plata was hardest hit with 91 reported deaths, and Greater Buenos Aires reported ten deaths. Is the worst flooding in La Plata’s history.[25] |
| 17 November 2013 | 18 | heavy rain | Cyclone Cleopatra, Northeast Sardinia. See Also 2013 Sardinia floods |
| 29 – 30 April 2014 | 2+ | heavy rain | Alabama, Florida |
| 7 June 2014 | 73 | rain storm | 2014 Baghlan floods High rainfall contributed to the flash flood which destroyed hundreds of mud homes.[26] |
| 27 June 2015 | 1 | heavy rain | 2015 Philmont Scout Ranch flash flood, Philmont Scout Ranch, New Mexico |
| 7 July 2015 | 0 | heavy rain | 2015 Ghost Ranch flash flood, Ghost Ranch, New Mexico |
| 14 September 2015 | 16+ | rain storms | 2015 Utah floods Sudden downpours caused flash flooding of canyons in Hildale, Utah, and Zion National Park, killing at least 16 and possibly 20 people.[27] |
| 25 October 2015 | 17+ | rain storms | Alexandria and Nile Delta region of Northern Egypt. Strong rains on 25 October and 4 November caused flash flooding and resulted in the deaths of at least 17 people, including five electrocuted when a tram power line collapsed into a puddle.[28] |
| 5 November 2015 | 3 | rain storms | Flash flooding occurred in the Jordanian capital Amman causing 3 deaths when a severe thunderstorm lasted over 30 minutes. |
| 30 July 2016 | 2 | heavy rain | 2016 Maryland flood – A historic and deadly flash flood struck Ellicott City, Maryland due an estimated 6 inches (15 cm) of rain falling in the city within only two hours. It was said to have been a “1000-year flood” event by the NWS. |
| 15 July 2017 | 10 | heavy rain, wildfire burn scar | 2017 Payson flash floods A flash flood occurred at a popular swimming hole near Payson, Arizona, the flood killed 10 members of an extended family. |
| 15 November 2017 | 24 | heavy rain | 2017 West Attica floods Flash floods occurred in the towns of Mandra, Nea Peramos and Megara, towards west of Athens, due to heavy rain. 24 people were killed due to this disaster along with significant damage to property.[29] |
| 26 April 2018 | 10 | heavy rain | Heavy rainfall in the Negev desert caused a flash flood in the Tzafit canyon trapping a group of hikers and resulting in 10 fatalities.[30] |
| 27 May 2018 | 1 | heavy rain | 2018 Maryland flood Just two years after a historic and deadly flash flood struck the region, another heavy rain bought around 8 inches (20 cm) in two hours to |Elliccott City, Maryland]], resulting in a disastrous that was assessed to be much worse than the previous one. This was the second “1000-year flood” event in two years. |
| 4 July 2018 | 0 | heavy rain | Heavy rainfall caused flash flooding in Houston, Texas, and the surrounding area, causing the cancellation of 4 July festivities.[31] |
| 5 July 2018 | 0 | heavy rain | Heavy rainfall caused flash flooding in Canton, Ohio, and other parts of Stark County.[32] |
| 21 August 2018 | 11 | heavy rain | A flash flood in a gorge in the southern Italian region of Calabria killed 11 hikers.[33] |
| 25 October 2019 | 10 | heavy rain | Heavy rainfall, total 60 to 120 millimetres (2.4 to 4.7 in) per an hour, and 160 to 280 millimetres (6.3 to 11.0 in) on twelve hours precipitation, and resulting to flash flooding, landslide around Boso Peninsula, Chiba Prefecture, Japan.[34] |
| 20 July 2021 | 302 (50 missing) | heavy rain | According to China Meteorological Administration official confirmed report, a heavy rain 617.1 millimetres (24.30 in) past three days by 20 July, including 201.9 millimetres (7.95 in), per a single hour in Zhengzhou, Henan Province, China. According to Chinese government official confirmed report, flood swept and many persons and vehicles struck in downtown area, and part section of Zhengzhou Subway Line 5 also damaged, and flash flooding hit neighborhooud Kaifeng, Luohe, Xinxiang, total government and economic damaged on 90.98 billion renminbi (14.08 billion US dollars).[citation needed] |
| 12 August 2021 | 21 (4 missing) | heavy rain | According to China Meteorological Administration official confirmed report, a heavy rain 459 millimetres (18.1 in) to 519 millimetres (20.4 in) past 18 hours by 12 August in Suizhou, Yicheng, Liulin, Hubei Province, China. including 117.9 millimetres (4.64 in), per a single hour in Liulin. According to Chinese government official confirmed report, flood swept and many persons and vehicles struck in widely area.[citation needed] |
| 26 July 2022 | 1 (0 missing) | heavy rain | 12.86 millimetres (0.506 in) was reported in a span of 5 hours in July 26, 2022 in St. Louis, Missouri.[citation needed] |
