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

Événement

Learning Objectives: 

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

  • Create a flood map using Google Earth Engine
  • Generate a map characterizing areas where landslides have occurred
  • Generate a digital... read more

The Asia-Pacific region faces major disaster risks in the form of earthquakes and tsunamis, tropical cyclones and typhoons, landslides, flash floods, avalanches and glacial lake outburst floods (GLOFs). Due to the large ... read more

This webinar series will build on the knowledge and skills previously developed in ARSET SAR trainings. Presentations and demonstrations will focus on agriculture and flood applications. Participants will learn to characterize floods with Google Earth Engine. Participants will also learn to analyze synthetic aperture radar (SAR) for agricultural applications, including retrieving soil moisture and identifying crop types.

Learning Objectives: 

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

  1. analyze SAR data in Google Earth Engine
  2. generate soil moisture analyses
  3. identify different types of crops
Course Format: 
  • This webinar series will consist of two, two-hour parts
  • Each part will... read more

Actualités

Preliminary flood map created by UN-SPIDER using Sentinel-1 radar imagery.

The 2019 rainy season in the Far North region of Cameroon has caused the Logone river to overflow and flood the Zina (Logone-et-Chari department), Maga and Kai-Kai districts (Mayo Dany) in the country's Far North region. The United Nations Office for the Coordination of Humanitarian Affairs reports that at least 60 out of 110 villages in the Zina district - 19,359 people - are affected, while 15 villages with a total of 16,215 people are affected in the Kai-Kai district.

UN-SPIDER has requested the activation of the International Charter Space and Major Disasters for the floods on behalf of the Department of Civil Protection (DPC) of Cameroon. SERTIT is acting as the project manager for this activation. An... read more

Publishing date: 19/10/2019
Flood inundation map developed using Sentinel-1 satellite data, as part of the rapid mapping response under the SERVIR-HKH Initiative at ICIMOD. Map: Kabir Uddin/ICIMOD.

In July 2019, Bangladesh, India and Nepal experienced floods and landslides during the South Asian... read more

Publishing date: 25/09/2019

Recommended Practices

Floods and landslides are the first and fourth most frequent disasters around the world (Petley, 2012). There are several examples of downstream flooding caused by massive mudslides where rapid mapping is an indispensable tool for supporting disaster management activities by civil protection authorities. Since July 2014, the Copernicus programme of the European Union has been providing free-of-charge access to Sentinel-1 radar data coveirng the entire world. This allows for the exploration of new applications to strengthen hazard monitoring and disaster mitigation activities. This UN-SPIDER...

UN-SPIDER Training Activity

International Training Programme on Space-Based Technologies for Disaster Risk Assessment | Date of training: 05/09/2019 to 09/09/2019

Data Source

Publishing institution: Joint Research Center, European Commission (JRC)
GIS Malawi is a webmapper which provides various vector and raster layers covering a broad range of topics including natural hazards.

Pages

Hazard group

Terms in the same hazard group

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