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.


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).

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SAM Satellite

Gaofen-1 (gao fen = high resolution) is the first of a series of high-resolution optical Earth observation satellites of CNSA (China National Space Administration), Beijing, China. The civilian HDEOS (High-Definition Earth Observation Satellite) program was proposed in 2006, it received government approval and was initiated in 2010. China plans to launch six HDEOS spacecraft between 2013 and 2016. The major users of the observation data will be the Ministry of Land and Resources, Ministry of Environmental Protection, and the Ministry of Agriculture.
The GF-1 spacecraft was launched on April 26, 2013 on a CZ-2D (Long March -2D) vehicle from the JSLC (Jiuquan Satellite Launch Center) in northwest China.

PMC (PAN and Multispectral camera)
WFI (Wide Field Imager)

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Landsat 8 launched on February 11, 2013, from Vandenberg Air Force Base, California, on an Atlas-V 401 rocket, with the extended payload fairing
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Landsat 8 was developed as a collaboration between NASA and the U.S. Geological Survey (USGS). NASA led the design, construction, launch, and on-orbit calibration phases, during which time the satellite was called the Landsat Data Continuity Mission (LDCM). On May 30, 2013, USGS took over routine operations and the satellite became Landsat 8. USGS leads post-launch calibration activities, satellite operations, data product generation, and data archiving at the Earth Resources... read more

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Launched in December 2011, Pleiades is a constellation of two very-high-resolution satellites capable of acquiring imagery of any point on the globe in under 24 hours for civil and military users.
Pleiades has been observing and mapping Earth’s surface at a resolution of just 70 cm every day since December 2011. Comprising the Pleiades 1A and Pleiades 1B satellites, this space imaging system complements the capabilities of the SPOT satellites, which have a wider field of view than Pleiades but lower spatial resolution. What’s more, as Pleiades 1A and 1B are in the same orbit, together they can image anywhere on Earth in less than 24 hours. Pleiades imagery is used for both civil and military applications, for example to track urban expansion, monitor the planet’s active volcanoes or assist road and railway routing, and to locate adversaries’ military installations for mission planning. Pleiades’ key asset is an extremely sensitive optical instrument that reduces the exposure... read more

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SJ-9 (Shi Jian = Practice) is a technology demonstration formation flight mission of CNSA (China National Space Administration), consisting of two minisatellites of different sizes and capabilities, SJ-9A and SJ-9B. The overall mission concept is to demonstrate the functionality of a range of newly developed formation flying techniques and components and to validate the formation flight GNC (Guidance, Navigation and Control) algorithms and strategies of the system configuration.
SJ 9A is based on the CAST-2000 bus. It conducts in-orbit experiments for electric propulsion, high-precision- and high-stability control systems, high-efficienent power supply and advanced thermal control technology. The satellite features also instruments for Earth observation and component tests of indigenously developed technology.

Instruments: High-performance small camera
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VRSS-1 is Venezuela's first remote sensing satellite.
On May 26, 2011, a contract for the manufacture and launch of the VRSS-1 spacecraft was signed in Caracas, Venezuela, between the government of Venezuela (the Ministry of People’s Power for Science, Technology and Intermediate Industries) and CGWIC (China Great Wall Industry Corporation), a subsidiary of CASC (China Aerospace Science & Technology Corporation).
After launch, the VRSS-1 satellite was renamed in honor of Sebastián Francisco de Miranda (1750-1816), a Venezuelan revolutionary hero, known as ‘Generalissimo’ Francisco de Miranda, who had planned the independence of the Spanish colonies in South America.
Partner organizations in the VRSS-1 program: ABAE is the Space Agency of Venezuela, subordinated and funded by the Venezuelan Ministry of People’s Power for Science, Technology and Innovation (MPPCTI). ABAE is in charge of in-orbit operations, management and application of the VRSS-1 satellite mission... read more

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METOP (Meteorological Operational) is Europe's first polar-orbiting operational meteorological satellite. It is the European contribution to the Initial Joint Polar System (IJPS), a co-operative agreement between Eumetsat and the US National Oceanic and Atmospheric Administration (NOAA) to provide data for climate and environmental monitoring and improved weather forecasting.
Metop-A (launched on 19 October 2006), Metop-B (launched on 17 September 2012) and Metop-C (launched 7 November 2018) are in a lower polar orbit, at an altitude of 817 kilometres, to provide more detailed observations of the global atmosphere, oceans and continents. The three satellites will operate in unison for as long as Metop-A's available capacities bring benefits to users. NOAA still continues to operate its mid-afternoon orbit satellite service as part of the Polar Orbit Enviromental Satellites (POES) system.

A/DCS (Advanced Data Collection System)
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SPOT-6 (Système Pour l’Observation de la Terre) is an optical satellite built by Astrium and was successfully launched on September 9, 2012 with SPOT 7 launched on June 30, 2014.
The new generation SPOT-6 and 7 optical satellites feature technological improvements and advanced system performance allowing continuity in the SPOT constellation through to 2024. It is capable of imaging the Earth with a resolution of 1.5 meter panchromatic and 6 meter multispectral (blue, green, red, near-IR) and will offer imaging products to customers in defense, agriculture, deforestation, environmental monitoring, coastal surveillance, engineering, oil, gas and mining industries.
The ability to respond accordingly to changing weather conditions, a reduced timeline for urgent tasking requests and an acquisition capacity of 3 million sq km per satellite shows an increased data capacity and simplified data access, major improvements in this generation of SPOT satellites.
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Kanopus-V (also spelling of Canopus-V N1) is an Earth observation minisatellite mission of the Russian Space Agency, Roskosmos and ROSHYDROMET/Planeta. The overall objective is to monitor Earth's surface, the atmosphere, ionosphere, and magnetosphere to detect and study the probability of strong earthquake occurrence.
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PSS (Panchromatic Imaging System)
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Today, weather satellites scan the whole Earth, meaning not a single tropical storm or severe weather system goes undetected. The early detection and warnings they provide have saved thousands of lives.
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GERB (Geostationary Earth Radiation Budget)
MSG Comms (Communications Package for MSG)
SEVIRI (Spinning Enhanced Visible and Infra-Red Imager)

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KOMPSAT-3 is an optical high-resolution Korean observation mission of KARI (Korea Aerospace Research Institute). The mission is funded by MEST (Ministry of Education, Science and Technology). The project was started in 2004. The objective is to provide observation continuity from the KOMPSAT-1 and KOMPSAT-2 missions to meet the nation's needs for high-resolution optical imagery required for GIS (Geographical Information Systems) and other environmental, agricultural and oceanographic monitoring applications.

A further goal is to meet the nation's satellite demand and form a technology infrastructure that will make inroads into the world space industry at a stage when the industry is improving the capability to design and develop highly advanced remote sensing satellites.

Instrument: AEISS (Advanced Electronic Image Scanning System)
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