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

GP-STAR factsheet

Publishing institution: Food and Agriculture Organization of the United Nations (FAO)

The Agricultural Stress Index System (ASIS) is based on 10-day (dekadal) satellite data, of vegetation and land surface temperatures, from the METOP-AVHRR sensor at 1 km resolution. Data for Country-level ASIS is freely available for download from FAO FTP. Time Series Database from 1984.

 

Publishing institution: Copernicus Emergency Management Service (Copernicus EMS)

CEMS is a core service of the European Union’s Earth Observation programme Copernicus. It supports all phases of the disaster management cycle by delivering warnings and risk assessments of floods and forest fires and by providing geospatial information derived from satellite images on the impact of natural and man-made disasters all over the world (before, during or after a crisis). The two Mapping services of CEMS (... read more

Publishing institution: Disaster Management Training and Education Centre for Africa (Dimtec), South Africa

Drought classification framework based on a suite of indicators is proposed for South Africa calibration and national adaptation process

 

Publishing institution: Chinese Academy of Sciences – World Academy of Sciences Centre of Excellence on Space Technology for Disaster Mitigation (CAS‐TWAS SDIM)

The Drought-Watch Indices module can calculate five EO-derived drought indices (VCI, TCI, VHI, NDWI, NDDI, and VSWI) and two meteorological indices (SPI and AI) in four temporal scales (day, pentad, dekad and month) by the composition parameters. Both single index and combination index are applied for the drought classification in drought module and the results are demonstrated and saved in different forms.

News

Dry soil

A break in the heat wave that hit Europe in the summer of 2018 is giving a reprieve to many people who had been suffering from the heat. However, great damages to the vegetation and harvest remain. In Germany, the Association of Farmers has reported damages from the dry spell of over EUR 1 billion. Vegetation growth in various regions and whether there is a long-term trend in vegetation development can be assessed using satellite... read more

Publishing date: 17/08/2018
Sustainable use of groundwater during the dry season is crucial for paddy farming in Saptari, Nepal. Image: ICIMOD

According to a recent report published by the International Centre for Integrated Mountain Development (ICIMOD), space-based information can play a key role in the monitoring of agricultural droughts and forest fires. The "Building Mountain Resilience: Solutions from the Hindu Kush Himalaya" report examines the changing problems facing the Himalayan region of South Asia and highlights the potential for technologies, including space-based applications, to inform communities, practitioners, decision-makers and governments alike, and build more resilient... read more

Publishing date: 15/08/2018

Data Source

Publishing institution: European Space Agency (ESA)
The main objective of the SENTINEL-3 mission is to monitor sea and land surface temperature, sea surface topography and ocean and land surface colour with high accuracy and reliability. The high resolution data is meant to support ocean forecasting systems, environmental monitoring and climate monitoring. ESA and EUMETSAT will jointly operate the SENTINEL-3 mission and bothy institutions provide access to the processed data. Sentinel 3 carries four main instruments: the OLCI, SLSTR, Altimetry and a MWR Microwave Radiometer.

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