Flood

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).

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Related content on the Knowledge Portal

  • Torrential rain since Thursday, September, 2nd 2010 lead to floods in the main part of Senegal and many towns. The most affected, Dakar, the capital gathers in his suburbs (Pikine and Guediewaye Departements) more than 30,000 affected households. Departement of Velingara in the South of Senegal gathers 1,042 affected people with 105.5 ha of flooded farms.
    Source: OCHA- ROWCA

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    Status Update: 13/09/2010

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    Contacts:

    UNOOSA/UN-SPIDER

    read more
  • - 44 people have been reported dead, and some 50,364 people have been affected by recent torrential rains.

    - The National Coordinator for Disaster Risk Reduction has declared a national level orange alert while the State of National Calamity continues.

    - The UN System and the Humanitarian Network have finalized the flash appeal review process In order to continue to support most vulnerable populations.

    - UN agencies are currently monitoring the situation on the ground in order to respond and to evaluate the needs of the affected population.

    - Food distribution continues in shelters and affected areas around de country.

     

    Source: ReliefWeb
     

    DEADLY landslides in Guatemala are the culmination of one of the worst rainy seasons in half a century, aid workers at Plan International report.

    In June, 80,000 people were left homeless…

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  • Floods have affected more than 340 families countrywide following torrential rains.

    Source: Glidenumber

  • Around 2000 are affected by the massive floods in Bendang Man, Sik Kedah. Malaysia Red Cross started emergency operation to deliver humanitarian aid.

    Source: glidenumber

    The month of Ramadan never stop the Malaysian Red Crescent volunteers to help those in needs. Their highly commitment and dedication bring them to Kedah to help around 2000 floods victims affected by the massive floods in Bendang Man, Sik Kedah. The convoy left for Kedah yesterday and led by Jasni Hashim, MRC Director of Operations with the emergency supplies to children and families affected. The supplies comprises of drinking water, clothes and personal hygiene kit.

    Source: Malaysian Red Crescent

  • Intermittent moderate to heavy rains that prevailed from July 26-30, 2010 trigerred the overflowing of Simuay River and other tributaries which caused flooding in the municipalities of Sultan Kudarat, Pagalungan and Datu Montawal, all in Maguindanao; Lambayong, Sultan Kudarat Province; and Kabacan, North Cotabato, thus, affecting 16,184 families in 35 barangays in Region XII.

    Source: glidenumber

    For more summary of flooding in Region XII please see also official NDCC update.

     

  • On 6 August 2010, at least 80 people were killed and more than 200 injured when heavy rains triggered flash floods and landslides in the frontier town of Leh, police said.

    Source: glidenumber

    SRINAGAR, India, Aug 7 (Reuters) - Heavy rainfall was hampering rescue and relief efforts in India's Himalayan region of Ladakh on Saturday, the army said, after flash floods killed at least 113 people.

    Scores of people were missing, and some foreign tourists were also believed to have been affected, the foreign ministry said.

    The airport in Leh town, dotted with Buddhist monasteries, was open and planes carrying disaster response teams, doctors and communications equipment have been dispatched.

    Source: ReliefWeb

  • North Korea state-run news agency says heavy rains have caused great damage to the country?s economy and unspecified human losses. The report said more than 5,500 houses and more than 350 public buildings have been destroyed, while almost 15,000 hectares of farmland is submerged.

    Source: glidenumber

    The report did not say how many people have been killed or injured. But China's state-run Xinhua agency reported Wednesday that flooding in Jilin province, which borders North Korea, has killed more than 70 people and forced the evacuation of close to 800,000.

    The North Korean agency said the government has put emergency relief procedures in place as weather officials predict more rain in the coming days.

    Source:…

    read more
  • Local authorities in the northern province of Lampang are expediting rescue operation to help over 300 families plagued by flash floods.

    Source: glidenumber

  • Floods have devastated the Basunkusu area, located in the northern part of the Equateur Province. Nearly 300 homes were totally destroyed, leaving an estimated 1,500 individuals homeless.

    Source: glidenumber

  • After approximately 100 hours of continuous rain, 84 municipalities of the state of Hidalgo are facing floods and landslides. So far 200 people had been evacuated in Hujutla, Tlanchinol and Orizatlan.

    Source: glidenumber

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