Drought

Lake Chad has shrunk dramatically over the last four decades due to a decrease in rainfall and an increase in the amount of water used for irrigation projects. Its surface area was 25 000 sq km in the early 1960s, compared with 1350 sq km in 2001. Image acquired 19 December 2007 by the MERIS (Medium Resolution Imaging Spectrometer) instrument aboard ESA’s Envisat satellite. Image: ESA, CC BY-SA 3.0 IGO.

Definition

Drought may be considered in general terms a consequence of a reduction over an extended period of time in the amount of precipitation that is received, usually over a season or more in length. It is a temporary aberration, unlike aridity, which is a permanent feature of the climate. Seasonal aridity (i.e., a well-defined dry season) also needs to be distinguished from drought. It should be noted that drought is a normal, recurrent feature of climate, and it occurs in virtually all climatic regimes (UNDDR).

Facts and figures

Droughts are often predictable: periods of unusual dryness are normal in all weather systems. Advance warning is possible (WHO).

By 2025, 1.8 billion people will experience absolute water scarcity, and 2/3 of the world will be living under water stressed conditions (UNCCD).

Drought can be defined according to meteorological, agricultural, hydrological and socio-economic criteria.

  • Meteorological, when precipitation departs from the long-term normal
  • Agricultural, when there is insufficient soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought is typically evident after meteorological drought but before a hydrological drought
  • Hydrological, when deficiencies occur in surface and subsurface water supplies
  • Socio-economic, when human activities are affected by reduced precipitation and related water availability. This form of drought associates human activities with elements of meteorological, agricultural, and hydrological drought (FAO).

Related content on the Knowledge Portal

Data Source

Population Density Map. Image: Facebook Connectivity
Publishing institution: Facebook Connectivity Lab, Center for International Earth Science Information Network (CIESIN) - Columbia University
Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.
Population Density Map. Image: Facebook Connectivity
Publishing institution: Facebook Connectivity Lab, Center for International Earth Science Information Network (CIESIN) - Columbia University
Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.

Actualités

Snapshot of the SIRIS platform in action. Image: Mexican Space Agency (AEM)

In collaboration with the National Commission for Space Activities (CONAE) of Argentina, the Mexican Space Agency (AEM) recently launched a digital platform to improve the integration of satellite data for environmental monitoring in Latin America. The Comprehensive Regional Satellite Information System (SIRIS) provides access to satellite information in order to enhance decision-making and facilitate disaster management.

The SIRIS platform provides access to satellite imagery for different areas. The platform supplies information on the agriculture and forestry sector to better monitor the impact of natural disasters on agricultural production and woodland. It also offers up-to-date and archived data on fires to strengthen early warning and build long-term resilience. On floods, information provided by SIRIS indicates the water level to improve damage evaluation of the impacted area and facilitate humanitarian relief. In... read more

Publishing date: 20/12/2020
The signing ceremony of the ROSE-L mission. Image: ESA.

The European Commission plans to rapidly expand its environmental monitoring programme Copernicus. For this purpose, the European Space Agency (ESA) recently pledged 2.55 billion Euros towards contracts to advance the production of six new Copernicus satellite missions. The final of the six contracts was signed last Thursday between ESA and Thales Alenia Space for a mission that will provide new and important information to climate research and disaster management.

The high-priority Copernicus Radar Observation System for Europe in L-band (ROSE-L) mission is planned to launch in 2028 for a period of 7.5 years. The ROSE-L mission will orbit Earth every few days at an altitude of 690km and will carry a L-Band synthetic aperture radar (SAR). With a wavelength of approximately 23cm... read more

Publishing date: 18/12/2020
Screenshot of the SMAP tool in action. Image: NASA

Officially launched in 2015 by the National Aeronautics and Space Administration (NASA), the SMAP mission is an orbiting satellite that measures the amount of wetness in the top layer of soil incrementally every 2-3 days. These Soil Moisture Active Passive (SMAP) measurements rely on radiation frequencies that point to different levels of moisture on the surface of  earth’s soil and are useful for scientists because it allows them to construct maps indicating the level of soil moisture globally. Acknowledging the relevance and usability of this data for the field of disaster management, NASA recently integrated the SMAP data into its Disasters Mapping Portal

The Disasters Mapping Portal has been developed by the Geographic Informations Systems (GIS) Team at NASA in an effort to make their satellite data... read more

Publishing date: 25/11/2020
Cover of the IFRC World Disasters Report 2020. Image: Indian Red Cross Society.

A new report by the world’s largest humanitarian aid network highlights global disasters, populations most vulnerable to them and the efforts of local institutions in preventing, preparing for and responding to them. The 2020 edition of the World Disasters Report, “Come Heat or High Water”, was launched virtually from the offices of the International Federation of Red Cross and Red Crescent Societies (IFRC) in Vienna on November 16. This year’s report discusses climate- and weather-related disasters and their humanitarian impact. It argues for the usefulness of smart financing and space-based information in disaster management support.

The report warns that the global effort to address climate change is leaving behind countries most vulnerable to... read more

Publishing date: 19/11/2020
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 disaster management stakeholders... read more

Publishing date: 28/09/2020
IWMI staff receiving the GeoSpatial World Excellence Award 2020. Image: IWMI.

The International Water Management Institute (IWMI), a UN-SPIDER Regional Support Office, has won an award for its innovative work using remote sensing technology to help nations monitor and mitigate the impacts of drought. The Institute received the GeoSpatial World Excellence Award 2020 in recognition of the positive impact of its South Asia Drought Monitoring System (SADMS). Since IWMI launched SADMS in 2014, the system has guided national, state and district-level authorities in India and Sri Lanka to take timely action to prepare for drought.

The South Asia Drought Monitoring System (SADMS) provides maps of drought conditions that are produced and maintained at IWMI. Numerous drought indices - including the Integrated Drought Severity Index (IDSI), Standardized Precipitation Index, and Soil Moisture Index - have been developed to provide advanced drought monitoring and assessment information. The system has three components:... read more
Publishing date: 27/09/2020
Regional Support Offices mentioned:
Screenshot of the Earth Map platform.

Google and the Food and Agriculture Organization (FAO) of the United Nations have launched a new tool that provides access to multidimensional maps and statistics showing key climate and environmental trends. Earth Map draws on the processing power of Google Earth Engine and aims to help develop insights based on satellite and FAO’s agriculturally-relevant data alike. It follows the joint development by Google and FAO of the Collect Earth platform for forest and land cover assessments, and integrates with the recently launched FAO Hand-in-Hand geospatial platform.

Tapping into the wide range of multi-temporal and quasi real-time satellite data available through Google Earth Engine, Earth Map provides... read more

Publishing date: 18/09/2020

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

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