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).

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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.

... read more

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... read more

Launch date:
23/07/1972

Noticias

GloFAS forecast for parts of Central America on 3 November.

When disaster looms, early warning about potentially affected areas and the extent of the event are critical for disaster management efforts. Using in situ and... read more

Publishing date: 20/11/2020
The Geostationary Operational Environmental Satellite 16 (GOES-16) captured this image of Eta around on November 3. Image: NASA Earth Observatory.

The hurricane season in Central America normally quiets down at the end of October, but this year is one of those rare years when tropical storms and hurricanes in the region have occured beyond the typical season. With 30 events thus far, the 2020 tropical storm season in the Caribbean continues to take its toll in developing countries in Central America. Hurricane Eta entered the west coast of Nicaragua on 3 November as a Category 4 hurricane – the second-highest classification category. It triggered massive floods in Nicaragua, Honduras and Guatemala. In some regions, the magnitude of these floods was similar to those... read more

Publishing date: 16/11/2020

UN-SPIDER and its Regional Support Office in Nigeria, the National Space Research and Development Agency (NASRDA), conducted an online training on the UN-SPIDER Recommended Practice on Flood Mapping and Damage Assessment Using Sentinel-1 SAR Data in Google Earth Engine. Staff from NASRDA as well as from the National... read more

Publishing date: 24/10/2020
Regional Support Offices mentioned:
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 Response in Latin America” from 22 to 24 September 2020. The meeting was jointly organized with UN-SPIDER Regional Support Offices from Argentina (National Space Activities Commission, CONAE), Brazil (Federal University of Santa Maria, UFSM), Colombia (Geographic Institute Agustin Condazzi, IGAC), and Mexico (Mexican Space Agency, AEM).

In Latin America, UN-SPIDER and its Regional Support Offices have regularly carried out regional expert meetings, training courses and other joint efforts since 2011. The last Regional Expert Meeting took place in 2017 in Mexico.

The meeting, which consisted of three two-hour-long sessions, brought together a total of over 200... read more

Publishing date: 28/09/2020

Evento

Image: Rachman Reilli/Unsplash.

The Global Flood Partnership (GFP) is organizing four webinars as a replacement for the GFP annual in person meeting. These two-hour long webinars (ZOOM meetings/YouTube Streaming) are provided at no cost and take place on 4, 11, 18 and 25 November at 3pm (UTC + 1 hour). Recordings of the webinars can be accessed on YouTube following the events.

The webinars cover the following four topics:

  •  Session 1: Global flood monitoring (EO) - 4 Nov 2020
    • Brian Lander / Margot Van der Velden – WFP, Nobel Peace Prize awardees 2020: 'Taking WFP flood impact prediction and mapping to the next level' YouTube video recording: https://youtu.be/v3NwNcqUs2o
    • David Borges – NASA: 'GEO and CEOS Flood... read more

The University of Alaska Fairbanks has launched a MOOC about Synthetic Aperture Radar (SAR) remote sensing for disaster monitoring. SAR is a remote sensing technology that can see the ground even during darkness and through rain, clouds, or smoke. Participants of the course will gain an intuitive understanding of the information contained in SAR observations and... read more

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:

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