Inundación

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).

UN-SPIDER Regional Support Offices with hazard-specific expertise

Related content on the Knowledge Portal

  • The United Nations Office for Outer Space Affairs (UNOOSA), as part of the support it provides to Member States through its UN-SPIDER programme, has requested the activation of the International Charter "Space and Major Disasters" for monitoring the impact of the floods in the Islamic Republic of Iran caused by heavy rainfall in the southwestern provinces of Golestan and Mazandaran on 31 March. The Charter was activated on behalf of UN-SPIDER Regional Support Office the Iranian Space Agency (ISA), which is acting as project manager for the activation.

    A state of emergency has been declared by officials with at least 45 people killed and many more injured as flash flood water and mud damaged...

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    According to the WHO, every year disasters “kill around 90,000 people and affect close to 160 million people worldwide.” This training will show participants how NASA remote sensing data can be used to characterize and monitor disaster-related events and support relief efforts. Each session will cover a different disaster and its supporting data. Disaster scenarios include tropical storms, flooding, earthquakes, and landslides.

    Learning Objectives

    By the end of this training, attendees will be able to:

    • Identify NASA data products to characterize and monitor the disasters, Tropical Storms, Flooding, Landslides and...

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    A state of emergency has been declared by officials with at least 45 people killed and many more injured as flash flood water and mud damaged thousands of buildings and  more rainfall is expected in the coming days. Up to 56 villages near the Dez and Karkheh rivers may need to be evacuated as water needs to be released from two dams.Officials reported that in the next five days around three billion cubic...

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    Regional Support Offices mentioned:
    31/03/2019
  • On 12 March, Nepal Telecommunications Authority (NTA) signed an agreement with French satellite operator Thales Alenia Space to build Nepal’s first communications satellite. The Nepalese government intends to use the satellite to provide nationwide internet access to its citizens, improve disaster management efforts and strengthen economic growth in the country.

    The development of Nepal’s own satellite system proves to be significant in terms of improving the country’s disaster management efforts. Nepal is regularly faces natural disasters such as droughts, floods, landslides, fires, and...

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    The mission was a follow-up activity to the UN-SPIDER Technical Advisory Mission (TAM) conducted in July 2015 that assessed use of space-derived information in all aspects of disaster...

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    Regional Support Offices mentioned:
    20/03/2019
  • Participants are being trained in analyzing maps produced as part of International Charter activations. , Over 50 participants participated in the two training courses provided as part of the ISM. , Training participants from the Department of Disaster Management. , Training participants from key ministries of Myanmar. Image: UN-Habitat.

    As part of the technical advisory support it provides to countries worldwide, UN-SPIDER carried out an Institutional Strengthening Mission to Myanmar from 11 to 15 March 2019 upon the request of the government. This activity was jointly organized by UN-SPIDER and the United Nations Human Settlement Programme (UN-Habitat), under auspices of the Ministry of Social Welfare, Relief and Resettle­ment (MSWRR) of Myanmar. It was hosted by the Emergency Operation Centre (EOC). Experts from the Centre for Space Science and Technology Education in Asia and the Pacific (CSSTEAP), the International Centre for Integrated Mountain Development (ICIMOD) and Maxar contributed to the mission.

    The mission was a follow-up activity to the UN-SPIDER Technical Advisory Mission (TAM...

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    19/03/2019
  • Vietnamese and American researchers joined efforts to develop a satellite-based system approach to monitor and manage transboundary flooding.

    The teams from the Viet Nam National Center for Water Resources Planning and Investigation (NAWAPI) and the University of Washington co-developed and implemented an advanced water forecasting system. Recently, Viet Nam launched the satellite-based system aiming to improve timely access to upstream reservoir information in transboundary river basins of the Red and Mekong rivers. The satellite-based system provides various ways to achieve this objective.

    Estimate reservoir storage and outflow

    With the mass balance approach users can calculate reservoir storage and outflow with satellite data. The key inputs of the dam system are precipitation and inflow. Therefore, satellite precipitation data and hydrologic models provide...

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    06/03/2019
  • The Tanzania Commission for Science and Technology (COSTECH), in partnership with the Revolutionary Government of Zanzibar (RGoZ), has launched an initiative to produce detailed aerial imagery maps of the islands of Zanzibar. The cooperative project is called the Zanzibar Mapping Initiative (ZMI). This initiative has drawn global attention because the mapping is done entirely with drones; the ability to map is now available widespread at a local level. The maps produced are of exceptional spatial resolution. Additionally, their free and open source data sets includes a comprehensive compilation of available vector and raster data covering the whole of Tanzania. Users can find not only aerial imagery produced from drones, but everything from census data to land use layers.
    More information can be found on the ZMI project website: http://www.zanzibarmapping.com/
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    Publishing institution:
  • Assessments of flood risk, on global to local scales, are becoming more urgent with ongoing climate change and with rapid socioeconomic developments. Such assessments need information about existing flood protection, still largely unavailable. Here we present the first open-source database of FLood PROtection Standards, FLOPROS, which enables more accurate modelling of flood risk. We also invite specialists to contribute new information to this evolving database.

Term Parents

UN-SPIDER Regional Support Offices with hazard-specific expertise