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

Publishing institution: United Nations Office for Outer Space Affairs (UNOOSA)
The Space4Water Portal developed by UNOOSA present news, data and training information for all stakeholders involved in the space and water communities. It aims to provide access data and knowledge, to be creative and to realize their full potential in contributing to a world in which the availability and sustainable management of water and sanitation for all has become a reality. Launched in October 2018, the portal is building up available resources. It already presents training material related to flood mapping, and automating the production of global water maps using Sentinel-2 imagery.
Publishing institution: European Space Agency (ESA)
ESA's Earth Observation Thematic Exploitation Platform (TEP) is a browser for satellite imagery and specific products on an environmental topic. The TEP platforms are divided into 7 categories: Coastal; Forstry; Geohazards; Hydrology; Polar; Urban; and Food Security. Each platform is a collaborative, virtual work environment providing access to EO data and the tools, processors and Information and Communication Technology resources required to work with them. TEP aims to bridge the gap between the users and the data and tools.
Publishing institution: Airbus Defence & Space
Pleidas, TerraSar-X, SPOT and Elevation data available commercially from airbus, certain sample data sets at various locations available for free.
Publishing institution: Radiant Earth Foundation
The website: https://www.radiant.earth Help and Tutorials: https://help.radiant.earth/ Demos & Use Cases: https://demos.radiant.earth/
Publishing institution: Intergovernmental Authority on Drought and Development (IGAD)
ICPAC drought maps present current rainfall anomaly (Standardized Precipitation Index (SPI)), vegetation anomaly, hydrological condition and rangeland drought monitoring maps. ICPAC Flood Hazard and Risk Maps present flood hazard maps, population estimates, near-real time rainfall 10 day maps from TAMSAT, flood frequency maps for 100 years. Regional focus: Sudan, Ethiopia, Kenya, Tanzania, Somalia, South Sudan. TAMSAT is the acronym for Tropical Application of Meteorology Using Satellite Data and Ground-Based Observations which is a rainfall estimation and quality assessment system providing high-resolution (~4 km) , 10-daily (or monthly) pan-African rainfall estimates. The TAMSAT system is based on two cardinal data sets: 1) Rainfall estimates based on time-lapse analysis of the cloud-top temperature distribution and development observed every 30 minutes (every 15 minutes since July 2006) by thermal infrared (TIR) imagery from aboard the Meteosat satellites of the first and...
Publishing institution: NASA Earth Science Disasters Program
NASA's Earth Observing System Data and Information System (EOSDIS) is a program for archiving and distributing Earth science data from multiple missions to users.
Publishing institution: European Organization for the Exploitation of Meteorological Satellites (EUMETSAT)
Map Viewer that allows downloading and time series creation of meteosat products.

Event

La predicción y el monitoreo del agua y el clima extremo son una parte vital de la gestión de los recursos naturales de un área. En asociación con la UNESCO, ARSET está organizando una capacitación de seis días sobre aplicaciones de percepción remota por satélite para la gestión de cuencas hidrográficas.
Los asistentes aprenderán sobre técnicas de percepción remota aplicables a la gestión de recursos hídricos a través de estudios de casos y ejercicios.
Los temas incluirán:

  • Monitoreo y predicción de desastres relacionados con el agua.
  • Estimaciones de precipitación
  • Evapotranspiración de la humedad del suelo
  • Radar de apertura sintética (acceso y procesamiento de datos).
  • Clasificaciones de tierras

... read more

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