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

  • Flash floods triggered by days of heavy rain have killed at least four people, forced mass evacuations and cut off power to thousands in central Europe.

    Source: http://glidenumber.net/glide/public/search/details.jsp?glide=19103

  • Flash floods triggered by days of heavy rain have killed at least four people, forced mass evacuations and cut off power to thousands in central Europe.

    Source: http://glidenumber.net/glide/public/search/details.jsp?glide=19101

  • Source: http://glidenumber.net/glide/public/search/details.jsp?glide=19099

    Heavy ranfall received since 14th May 2010, and was continuing till date. Most of the areas in Colombo, Gampaha and Kalutara district has been affected by floods. Transport was difficult due to submerge of main roads and diffuclt to make emergency response. In additiona to that more than 80,000 families has been directly affected by floods. More over there has been only 1 death and few injusres has been reported. Since the data is still receiving the the actual figures may increase. Situation reports has been posted to DMC web site:

    www. dmc.gov.lk

     

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  • On 4 January 2010, a massive landslide triggered nearly 1.5 KM wide blockage (referred to as the ‘Dam’) across Hunza River and Karakoram Highway (KKH) at Ataabad, 15 KMs east of Karimabad ( Hunza-Nagar district). Loss of life in Attabad was prevented through timely evacuations. However, humanitarian consequences of the disaster are:-
    · 20 died in an adjoining village of Sarat and 7 were injured;
    · 56 houses were destroyed in Ataabad and Surat and 60 were damaged;
    · 252 families are living in IDP camps in Karimabad, Hunza (142 families) and in Shishket (110 families), upper Hunza.
    Blockage of the Hunza River has created a Lake that extends nearly 15 kilometers into Gojal Tehsil of upper Hunza. The Lake has inundated a stretch of KKH including a bridge at Shishket. Village Ainabad and parts of village Shishkat are inundated and Gulmit is vulnerable. 110 families have been displaced and valuable agricultural land and fruit orchards are lost. 30,000 population in upper…

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  • Heavy rains caused flooding in 40 districts surrounding the Kur (Kura), Azerbaijan's main river. 20,000 homes have been flooded, 300 of them ruined, and 2,000 fell into disrepair. 50,000 hectares of cultivated land and pasture are under water.

    Source: GlideNumber

  • The torrential rains of 7 May, 2010, caused floods and mudslides in Tajikistan. In total 10 districts were affected in the south regions, of wich Vose, Muminabad, Temurmalik, Baljuvon and Shurabad districts and Kulyab town of Kulyab region, as well as Nurek, J. Rumi, Yovon and Jilikul districts of Kurgan-tube region. According to the preliminary data received from RCST regional branches, the average number of disaster affected residencies in both regions is some 1059 houses (or 6354 people), out of which 179 houses totally destroyed. On the report of RCST staff and volunteers 60 people were killed, but at this stage only 13 people officially reported by the government, 40-50 are missing, 40 hospitalized and 85 injured.

    Source: GlideNumber

     


    Available Space-based Information for: Floods in Tajikistan (May 7 - ongoing) 

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  • Rainfall and torrential flooding in western province of Herat has devastated many areas, killing some 14 people, including seven children, injuring 30 others, damaging more than 250 houses and destroying around 300 hectares of agricultural land.

    Source: GlideNumber

  • Since March 1st 2010, the long rains have been pounding most parts of Kenya resulting in flood situations in parts of the Kenya.
    The floods have claimed 56 lives country wide; over 9,135 house holds have since been displaced and over 90,000 persons affected.
    As a result of the incident rains and run-off water from the Ethiopian highlands at the Kenya Ethiopia border have resulted in widespread floods in the vast district. The Ethiopian side has also issued a flood warning for the Kenyans living in the shadow of Wirwita dam in Ethiopia since the dam is about to reach overspill level. As a result, over 1000 families have evacuated from the projected course of the waters from Wirwita dam.


    Due to the vastness of Garissa district, limited GSM coverage, impassable roads, and the exorbitant costs of and limitations of chartering airplanes or choppers for aerial assessment and the prevailing humanitarian case the Emergency Operations Center (EOC) of Kenya Red Cross Society…

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  • The Caprivi region, particularly those constituencies traversed by the Zambezi and Chobe rivers which are Kabbe and Katima Rural have experienced high water flows arising from Zambia causing severe flooding.

    Source: GlideNumber

  • Hundreds of families affected by floods caused by heavy rains that started with the beginning of the winter (rainy) season

    Source: GlideNumber

    The Colombian Red Cross said Wednesday that 3,000 families across the country have been affected the floods, landslides and high winds that have battered the country in the last two weeks, according to Caracol Radio.

    The central Colombian department of Risaralda was battered with heavy rains and gail force winds over Easter, leaving 80 families homeless.

    Most of the damage was in the departments of Antioquia, Cauca, Choco and Caqueta Quindio, but the Red Cross said that the families struggling to deal with the devastation were spread over twelve departments.

    The Red Cross has called on local authorities to implement permanent systems to monitor the levels of river and streams and the conditions of hillsides…

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