Flood

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).

Related content

SAM Satellite

Landsat 2 was launched into space onboard a Delta 2910 rocket from Vandenberg Air Force Base, California on January 22, 1975, two and a half years after Landsat 1. Originally named ERTS-B (Earth Resource Technology Satellite B), the spacecraft was renamed Landsat 2 prior to launch. The second Landsat was still considered an experimental project and was operated by NASA.
Landsat 2 carried the same sensors as its predecessor: the Return Beam Vidicon (RBV) and the Multispectral Scanner System (MSS).
On February 25, 1982 after seven years of service, Landsat 2 was removed from operations due to yaw control problems; it was offically decommissioned on July 27, 1983.

Instruments:
Return Beam Vidicon (RBV)
Multispectral Scanner (MSS)
 

Launch date:
22/01/1975

Landsat 1 was launched on July 23, 1972; at that time the satellite was known as the Earth Resources Technology Satellite (ERTS). It was the first Earth-observing satellite to be launched with the express intent to study and monitor our planet’s landmasses. To perform the monitoring, Landsat 1 carried two instruments: a camera system built by the Radio Corporation of America (RCA) called the Return Beam Vidicon (RBV), and the Multispectral Scanner (MSS) built by the Hughes Aircraft Company. The RBV was supposed to be the prime instrument, but the MSS data were found to be superior. In addition, the RBV instrument was the source of an electrical transient that caused the satellite to briefly lose altitude control, according to the Landsat 1 Program Manager, Stan Weiland.
To help understand the... read more

Launch date:
23/07/1972

Actualités

Participants at the virtual expert meeting. Image: UNOOSA.

In order to discuss and promote the use of space technologies in addressing natural hazards such as forest fires and landslides in Latin America, UN-SPIDER conducted a virtual regional expert meeting on the topic of “Space-based Solutions for Disaster Risk Reduction and Emergency... read more

Publishing date: 28/09/2020
A SpaceX Falcon 9 rocket launches the SAOCOM 1B satellite. Image: Manuel Mazzanti/CONAE

The Argentinean SAOCOM 1B satellite was successfully launched into orbit on 30 August 2020. Developed by the National Argentinean Space Commission (CONAE), this new satellite will join SAOCOM 1A and four Italian COSMO-SkyMed to complete the joint Italian-Argentinean Satellite System for Emergency Management (SIASGE). Like its predecessor, SAOCOM 1B was built in Argentina through a joint effort with private companies and universities. It will operate at an elevation of 620 kilometers above the surface of the Earth. A SpaceX Falcon 9 booster launched the satellite from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida, United States of America.

The SAOCOM 1B satellite has been fitted with a Synthetic Aperture Radar (SAR) sensor that makes use of microwaves in the electromagnetic L-band, which goes through clouds... read more

Publishing date: 14/09/2020
Regional Support Offices mentioned:
Tropical cyclone Fani over the eastern coast of India on 2 May 2019. Image: NASA.

According to the latest issue of an annual disaster statistics report, floods were the deadliest type of disasters in 2019, followed by extreme... read more

Publishing date: 20/08/2020
Floods in Bangladesh in 2019. Image: UN Women Asia and the Pacific.

The International Centre for Integrated Mountain Development (ICIMOD) is leveraging space-based information to support government and humanitarian agencies in the Hindu Kush Himalayan (HKH) region with timely information for flood early warning and inundation mapping. The efforts, which consist of developing a streamflow prediction system for flood early warning and of providing near real-time flood maps for disaster... read more

Publishing date: 19/08/2020
Areas flooded and damaged following cyclone Idai, northwest of Beira. Image: European Union/Christian Jepsen.

In recent years, Mozambique has suffered severe floods and droughts that have impacted urban and rural communities throughout the country. In the March and April 2019, tropical cyclones Idai and Kenneth triggered major floods in Mozambique, Malawi, Zimbabwe, and Comoros.  The Port of Beira was hard hit, as cyclone Idai destroyed transmission lines and bridges, leaving the port without access to these lifelines for several days.   In contrast the powerful El Niño event of 2016 triggered major droughts that affected most of the country. Thousands of farmers lost their crops and their cattle and had to rely on humanitarian assistance to cope with the impacts of this event.

Taking into consideration the benefits of the use of... read more

Publishing date: 10/08/2020
Regional Support Offices mentioned:

Événement

Participants at the virtual expert meeting. Image: UNOOSA.

En décadas recientes muchas comunidades en América Latina y el Caribe han experimentado desastres ocasionados por inundaciones, sequías, deslizamientos, terremotos, erupciones volcánicas y maremotos o tsunamis que han erosionado los logros asociados a procesos de desarrollo. Además, en este año 2020 la pandemia ocasionada por el virus COVID-19 ha impactado a muchos países del mundo, forzando a los gobiernos, al sector privado, a la sociedad civil y a organismos regionales e internacionales a modificar sus planes de trabajo. De manera paralela, varios países del Este de África, del Sudoeste de Asia y de América Latina están experimentando los impactos de la plaga de langosta.  

Convencidos que las tecnologías espaciales pueden jugar un papel preponderante en apoyar los esfuerzos que llevan a cabo las instituciones en materia de gestión para la reducción de riesgos, la preparación, la respuesta y la recuperación en caso de desastres; la Asamblea General de las Naciones Unidas... read more

Image: UFSM.

The Federal University of Santa Maria of Brazil (UFSM), in its role as a UN-SPIDER Regional Support Office (RSO), and UN-SPIDER joined forces to conduct a virtual seminar on the use of the UN-SPIDER Recommended Practices to process satellite imagery to map the geographic extent of floods, and to elaborate a series of maps that allow government agencies, as well as regional and international organizations, to assess the severity of droughts in particular years in comparison to droughts in other years. The webinar, conducted on 4 August 2020, brought together more than 30 officers of government agencies of Mozambique, as well as researchers, faculty members and students from various universities.

During the event, researchers from UFSM made participants aware of efforts by the... read more

Regional Support Offices mentioned:

Synthetic Aperture Radar (SAR) data can be acquired day and night, even in cloudy conditions... read more

Pages

Hazard group

Terms in the same hazard group

Zircon - This is a contributing Drupal Theme
Design by WeebPal.