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

  • Floods caused by the overflow of Salinas River in Sayaxche, Peten have affected 435 families and more than a thousand parcels of crops. Some 230 people from The Mollejon community are sheltered in schools.

    Source: glidenumber

     

  • Flood continuing since last week hit the north-central regions, killing 14, affecting over 31,000. Regional government is continuing search and rescue efforts.
     
    Source: glidenumber
     
    Also refer to information from GDACS and ReliefWeb.

    Status Update: 05/08/2010


    Contacts:

    UNOOSA/UN-SPIDER

    read more
  • A flood hit five villages in South Kalimantan. The flood had victimized around 1,640 families or 5,000 people.
     
    Source: glidenumber
  • At least 43 killed as a result of monsoon rains and flooding across the country.

    Source: glidenumber

    Monsoon rains continued in most parts of Punjab and Khyber Pakhtunkhwa provinces, while rain was forecasted for Sindh sometime late on Thursday.At least 12 people were killed in Lahore and other parts of northern Punjab and more than 16 were injured. In Lahore, 10 people reportedly lost their lives in rain-related incidents. A child was electrocuted in Lahore’s Chongi Amar Sadhu area, while a man died after the roof of his house collapsed in Manawan, reports quoted police sources as saying.
     
    Another man was electrocuted while 16 people were injured in two separate rain-related incidents in the city.
    Several localities came under knee-deep rain water in different parts of Lahore and people had difficult performing…
    read more
  • At least 33 people were killed and several others were missing following powerful floods in eastern Sudan on Thursday (15 Jul 2010)

    Source: glidenumber

  • In Japan floods and landslides triggered by record heavy seasonal rainfall have occurred nationwide since 11 June 2010.

    Source: glidenumber, glidenumber

  • Due to heavy rains at the end of June, and the consequent rise in river levels, more than 1,000 houses have been flooded in Chernivtsy and Ivano-Frankivsk regions.

    Source: http://www.glidenumber.net/

  • Since July 5 2010, the long rains have been pounding a part of the territory of the Republic of Moldova. A lot of localities were affected in the country, as Nemteni, Cotul Morii as well as Obileni. According to the preliminary data received from Emergency Service Centre of Moldova, the average number of disaster-affected residencies in the regions is some 600 houses. As a result, over 2000 people have been evacuated from the projected course of the waters.

    Source and more information on http://www.gov.md

     

    Available Space-based Information for: Floods in Moldova

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    Status Update: 09/07/2010

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    read more
  • Due to heavy rains in the past week water levels of several rivers in Bosnia and Herzegovina have risen. On 22 June water spilled out of the river beds in several municipalities, damaging land and residential objects across the Federation of Bosnia and Herzegovina as well as Republika Srpska and Br?ko district.

    Source: http://www.glidenumber.net/

  • Heavy rains which began in 23 June have caused floods in the north-east and north of Romania damaging and floods 4,384 households and affecting more than 12,237 people.

    Source: glidenumber

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