Inondation

This Copernicus Sentinel-1 image combines two acquisitions over the same area of eastern Iraq, one from 14 November 2018 before heavy rains fell and one from 26 November 2018 after the storms. The image reveals the extent of flash flooding in red, near the town of Kut. Image: modified Copernicus Sentinel data (2018), processed by ESA, CC BY-SA 3.0 IGO.

Definition

Flood is usually used as a general term to describe the overflow of water from a stream channel into normally dry land in the floodplain (riverine flooding), higher-than–normal levels along the coast and in lakes or reservoirs (coastal flooding) as well as ponding of water at or near the point where the rain fell (flash floods) (IRDR Glossary).

Facts and figures

Floods are the natural hazard with the highest frequency and the widest geographical distribution worldwide. According to the Organization for Economic Cooperation and Development (OECD) flooding is one of the most common, widespread and destructive natural perils, affecting approximately 250 million people worldwide and causing more than $40 billion in damage and losses on an annual basis (OECD).

Flooding occurs most commonly from heavy rainfall when natural watercourses lack the capacity to convey excess water. It can also result from other phenomena, particularly in coastal areas, by a storm surge associated with a tropical cyclone, a tsunami or a high tide. Dam failure, triggered by an earthquake, for instance, will lead to flooding of the downstream area, even in dry weather conditions.

Various climatic and non-climatic processes can result in different types of floods: riverine floods, flash floods, urban floods, glacial lake outburst floods and coastal floods.

Flood magnitude depends on precipitation intensity, volume, timing and phase, from the antecedent conditions of rivers and the drainage basins (frozen or not or saturated soil moisture or unsaturated) and status. Climatological parameters that are likely to be affected by climate change are precipitation, windstorms, storm surges and sea-level rise (UNDRR).

When floodwaters recede, affected areas are often blanketed in silt and mud. The water and landscape can be contaminated with hazardous materials such as sharp debris, pesticides, fuel, and untreated sewage. Potentially dangerous mold blooms can quickly overwhelm water-soaked structures. Residents of flooded areas can be left without power and clean drinking water, leading to outbreaks of deadly waterborne diseases like typhoid, hepatitis A, and cholera (UNDRR).

Further information

UN Guidelines for Reducing Flood Losses

OECD Report on Financial Management of Flood Risk

PreventionWeb Floods

UN-SPIDER Regional Support Offices with hazard-specific expertise

Title: Bureau Régional d'Appui de l'Allemagne

Title: Bureau Régional d'Appui de l'Argentine

Title: Bureau Régional d'Appui de l'Indonésie

Title: Bureau Régional d'Appui de la Grèce

Title: Bureau Régional d'Appui de la Roumanie

Title: Bureau Régional d'Appui des Etats-Unis d'Amérique

Title: Bureau Régional d'Appui du Brésil

Title: Bureau Régional d'Appui du Pakistan

Title: Bureau Régional d'Appui Nigéria

Title: Centre Asiatique pour la Prévention des Catastrophes (ADRC)

Title: Centre International pour le Développement Intégré des Montagnes (ICIMOD)

Title: Institut International de Gestion de l'Eau (IWMI)

Related content on the Knowledge Portal

Floods in Nepal

Unseasonably heavy rains in western Nepal left a trail of destruction Tuesday(05/10/2009), killing at least 36 people and injuring several others, official said. Government officials said landslides struck at least five districts in western Nepal while flash floods were reported in Nepal's plains, known as Terai, after heavy rain began falling Sunday evening.

Source:http://glidenumber.net/glide/public/search/details.jsp?glide=18924.
Floods in Kenya

On 21 September 2009, three people died and property was destroyed during floods that occurred in Kisumu and Nyando districts, Nyanza province. Floods in the Kisumu district occurred in Winam and Kadibo divisions, killing three (3) people and affecting about 10,000 people. Floods in the flood prone district of Nyando occurred in Miwani division. 1126 people (206 households) had their houses submerged and an additional 3,000 people were affected by the floods.

Source: http://www.glidenumber.net/glide/public/search/details.jsp?glide=18923&record=1&last=4.

read more
Floods in India

The heaviest flood in over a 100 years hit the Prakasam Barrage on Krishna River threatening several villages downstream even as the toll due to heavy rains and rampaging floods in Andhra Pradesh and Karnataka climbed to 205. Andhra Pradesh & Karnatka are under the grip of flash floods. Several towns and villages in the state, particularly in Kurnool, Mahabubnagar and Krishna districts in Andhra Pradesh, have been inundated with the mighty Krishna river and its tributaries in spate for the past four days.

Source: http://glidenumber.net/glide/public/search/details.jsp?glide=18922.

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Floods in Italy

Italian government declared a state of emergency after flash floods and mudslides hit the southern town of Messina in Sicily leaving at least 20 dead and 35 missing

Source: http://www.glidenumber.net/glide/public/search/details.jsp?glide=18920&record=1&last=4478
Floods in Azerbaijan

On 21 September 2009 heavy rainfall caused flooding of hundreds of houses and roads in central parts of Azerbaijan. The Hajigabul district is most affected and some 70 per cent of the territory was flooded. Latest information suggests that more than 5,000 people are affected. More than 2,300 houses have been damaged or destroyed. The Azerbaijan Red Crescent will provide food and non-food items to 300 families amounting to 1,200 persons in Navahi.

Source: http://www.glidenumber.net/glide/public/search/details.jsp?glide=18910&record=9&last=4478

Further Information

Reliefweb: http://www.reliefweb.int/rw/dbc.nsf/doc108?OpenForm&emid=FL-2009-000208-AZE

ADRC: http://www.adrc.or.jp/latestinfo/view_c.php?lang=en&KEY=FL-2009-000208-AZE
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Flooding in Georgia

Severe flooding in north Georgia has killed so far seven people, submerged homes, knocked out power and turned streams into rivers.

Source: International Charter

Floods in US Georgia, North Carolina, Alabama and Tennessee have claimed at least 8 lives, more than 220 have taken refuge in shelters.

Source: Glide number

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Flash Floods in Indonesia

At least 38 people were killed in flash floods in a remote region of Indonesia's North Sumatra province Tuesday, a spokesman for the provincial government said.

Source: Glide number
Floods in India

Continuous rainfall in the catchment areas of major rivers (Mahananda, Kosi, Kamla , Adhwara group of rivers,Bagmati, Kankai, Donk, Mecchi, Ratua and Bakra) and its tributaries both in Bihar and adjoining country Nepal is causing the prevailing flood situation in seven districts in Bihar. Darbhanga, Madhubani, Sitamarhi, Muzaffarpur,Katihar, Purnia and Kishanganj are the affected districts so far according to official sources. Media reports state that 11 districts are aff ected by the floods which include West Champaran, Saharsa, Supaul and Gopalganj in addition. According to the Ministry of Home Affairs, 1,246,000 people have been affected in the state and 32 human lives have been lost . Media reports state that more that 1.5 million people have been affected and 52 human lives have been lost. Official reports state that 8,100 people have been evacuated .

Source: Glide number
Floods in Mexico

Mexican Govt declared state of calamity for Tlalnepantla de Baz and Atizapan de Zaragoza in the Estado de Mexico, due to heavy rains and floods.

Source: Glide number
Floods in Mexico

Mexican Government declared state of calamity for Tlalnepantla de Baz and Atizapan de Zaragoza in the Estado de Mexico, due to heavy rains and floods.

Source: Glide number