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: European Organization for the Exploitation of Meteorological Satellites (EUMETSAT)
Map Viewer that allows downloading and time series creation of Meteosat and Sentinel-3 products.
Publishing institution: United Nations Environment Programme (UNEP)
Satellite based flood maps

Actualités

Image of snow across northern Mongolia in January 2017 captured by NASA’s Aqua satellite. Image: Nasa Earth Observatory

A drought/dzud monitoring system known as “DroughtWatch-Mongolia” has been officially handed over to Mongolia on 17 September by the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) and the Institute of Remote Sensing and Digital Earth (RADI) of the Chinese Academy of Sciences.

DroughtWatch-Mongolia is a system based on satellite data which aims to provide real-time drought monitoring for disaster prevention and mitigation departments in Mongolia.

Following a request by Mongolia to UNESCAP to pilot its Regional Drought Mechanism, a project entitled, “Strengthening Mongolia's capacity to monitor and warn drought/dzud” was... read more

Publishing date: 02/10/2018

GP-STAR factsheet

Publishing institution: United Nations Office for Outer Space Affairs (UNOOSA)
After the TAM was conducted in Myanmar, innovative impacts were completed following a recommendation. “Emergency Operation Centre (EOC)”, which is comprised of four units including “Remote Sensing Unit” and “Risk Assessment and Emergency Response Unit” was established in the Ministry of Social Welfare, Relief & Resettlement (MSWRR). The capacity building of MSWRR and other related institutes in remote sensing and GIS were strengthened. The Disaster Management Training Centre now conducts courses in remote sensing/GIS. Myanmar has also become the first country in ASEAN to apply for universal access to the International Charter. Myanmar government is aware of the National Spatial Data Infrastructure (NSDI) and one map policy that has been initiated by the Ministry of Education is very crucial.  
Publishing institution: United Nations Office for Outer Space Affairs (UNOOSA)

In order to encourage the targeted retrieval of space-based information and data by disaster risk reduction practitioners, content on the Portal is systematically enriched with metadata. For instance, data sources are marked up with data about their file type, satellite/sensor and spatial coverage and whether they relate to the disaster risk management or emergency response phase. The tool features a range of filters that draw on the metadata, thereby allowing users to narrow down their search, for example, filtering available GIS software by hazard type. This ensures that users efficiently find the content that is most relevant to them. At the same time, the Portal encourages the discovery of resources related to those accessed by the user, by providing links to them on the same page. This allows for contextualisation and highlights links between resources from different areas that other platforms may display in an isolated fashion. A dynamic glossary, which means that terms in... read more

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