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).

Related content on the Knowledge Portal

SAM Satellite

The NPOESS Preparatory Project (NPP) was renamed to Suomi National Polar-orbiting Partnership (Suomi NPP) in honor of Verner E. Suomi, University of Wisconsin meteorologist, widely recognized as the "Father of Satellite Meteorology."

Launched from California’s Vandenberg Air Force Base a board a Delta-II Mission Launch Vehicle in October 2011, Suomi NPP is the predecessor to the JPSS series spacecraft and is considered the bridge between NOAA's legacy polar satellite fleet, NASA's Earth observing missions and the JPSS constellation. Suomi NPP was constructed with a design life of five years (although it’s still functioning normally).

and carries five state-of-the-art instruments: (1) VIIRS, (2) CrIS, (3) ATMS, (4) OMPS, and (5) CERES FM5.

VIIRS (Visible/Infrared Imager and Radiometer Suite)
CrIS (Cross Track Infrared Sounder)
ATMS (Advanced Technology Microwave Sounder)
OMPS (Ozone Mapping and Profiler Suite)... read more

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NASRDA (National Space Research & Development Agency) of Abuja, Nigeria has continued its association with SSTL, with two parallel projects - the NX and NigeriaSat-2. Like NigeriaSat-1, NX is based on the SSTL-100, but is being developed by a team of 26 Nigerian trainee engineers at SSTL's facilities in England. The Nigerian engineers will completely manage the total lifecycle of the NX and will be responsible for the delivery of the satellite to full flight specification.
Capacity building is central to the implementation of the Nigeria Space Program. As part of the Know-How Technology Training (KHTT) on the NigeriaSat-2 satellite project is the development of a training model (TM) named NigeriaSat-X. The TM will be used to give the KHTT’s hands on experience in the requirements specification, project management, system engineering, manufacture, test, assembly / integration and final system testing of a spacecraft. Unlike the NigeriaSat-1... read more

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In November 2006, NASRDA (National Space Research and Development Agency) of Abuja, Nigeria awarded a contract to SSTL (Surrey Satellite Technology Ltd.) of Guildford, UK, to develop and build NigeriaSat-2, including the related ground infrastructure and image processing facilities, together with an extensive training program to further develop an indigenous space capability in the Federal Republic of Nigeria. NASRDA is an agency under the Federal Ministry of Science and Technology of Nigeria established in 1999.
The objective of the NigeriaSat-2 mission is to provide high-resolution (Pan and MS) imagery in a swath width of 20 km. In addition, the spacecraft also carries a DMC continuity payload to provide observation continuity with NigeriaSat-1, launched in September 2003. - The imagery of both spacecraft will serve as a catalyst to the development of Nigeria's NGDI (National Geospatial Data Infrastructure) program. NASRDA will facilitate efficient production, management,... read more

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ResourceSat-2 is a data continuity mission of ISRO (Indian Space Research Organization) with improved spectral bands of the IRS-P6/ResourceSat-1. Each ResourceSat satellite carries three electrooptical cameras as its payload: LISS-3, LISS-4 and AWiFS. All the three imagers are multispectral pushbroom scanners with linear array CCDs as detectors.
ResourceSat-2 provides continuity and increases the observation timeliness (repetivity) in tandem with ResourceSat-1.
Additionally, the satellite carries an AIS payload for exactEarth (COMDEV), which is known as exactView 2 (EV 2).
Resourcesat-2 was launched in April 2011.

AWiFS (Advanced Wide-Field Sensor)
LISS-III (Linear Imaging Self-Scanning Sensor)
S-AIS (Satellite-based Self-Scanning Sensor)
LISS-IV Camera

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Cartosat-2 is an advanced remote sensing satellite with a single panchromatic camera (PAN) capable of providing scene-specific spot imageries for cartographic applications. The camera is designed to provide imageries with better than one meter spatial resolution and a swath of 10 km. The satellite will have high agility with capability to steer along and across the track up to + 45 degrees. It will be placed in a sun-synchronous polar orbit at an altitude of 630 km. It will have a revisit period of four days. The re-visit can be improved to one day with suitable orbit manoeuvres.

Several new technologies like two mirror on axis single camera, Carbon Fabric Reinforced Plastic based electro optic structure, lightweight, large size mirrors, JPEG like data compression, advanced solid state recorder, high-torque reaction wheels and high performance star sensors are being employed in Cartosat-2.

Instrument: PAN (Panchromatic Camera)
- high resolution... read more

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The TanDEM-X mission will survey all 150 million square kilometres of Earth's land surface several times over during its three-year mission. Apart from its high measuring-point density (a 12-metre grid) and high vertical accuracy (better than two metres), the elevation model generated by TanDEM-X will have another unrivalled advantage – being entirely homogenous, it will serve as a basis for maps that are globally consistent. Conventional maps are often fragmented along national borders, or difficult to reconcile as they are based on different survey methods or because of time lags between survey campaigns. Together TanDEM-X and TerraSAR-X are form the first configurable synthetic aperture radar interferometer in space. Besides this primary goal, the mission has several secondary objectives based on new and innovative methods such as along-track interferometry, polarimetric synthetic aperture radar interferometry, digital beamforming and bistatic radar. The TanDEM-X satellite... read more

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GOES 15 (GOES-P) is an American weather satellite, which will form part of the Geostationary Operational Environmental Satellite (GOES) system operated by the US National Oceanic and Atmospheric Administration. The spacecraft was constructed by Boeing, and is the last of three GOES satellites to be based on the BSS-601 bus. In addition to weather forecasting on Earth, a key instrument onboard GOES-P, the Solar X-Ray Imager (SXI), will help NOAA continue monitoring solar conditions.

GEOS&R (Geostationary Search and Rescue)
SEM/MAG (SEM / Magnetometer)
SXI (Solar X-ray Imager)
SEM/EPS (SEM / Energetic Particles Sensor)
SEM/HEPAD (SEM / High Energy Proton and Alpha Particles Detector)
SEM/XRS-EUV (SEM / X-Ray Sensor - Extreme Ultra-Violet Sensor)
DCIS (Data Collection and Interrogation Service)

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WorldView-2 (WV2) is a commercial imaging satellite of DigitalGlobe Inc. of Longmont, CO, USA (follow-on spacecraft to WorldView-1). The overall objective is to meet the growing commercial demand for high-resolution satellite imagery (0.46 cm Pan, 1.8 m MS at nadir - representing one of the highest available spaceborne resolutions on the market).

In the fall of 2003, DigitalGlobe had received a contract from NGA (National Geospatial-Intelligence Agency) of Washington DC to provide high-resolution imagery from the next-generation commercial imaging satellites. The contract award was made within NGA's NextView program. The NGA requirements called for imagery with a spatial resolution of 0.5 m panchromatic and 2 m MS (Multispectral) data.

The WorldView-2 sensor provides a high resolution panchromatic band and eight (8) multispectral bands; four (4) standard colors (red, green, blue, and near-infrared 1) and four (4) new bands (coastal,... read more

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The Deimos-1 mission is fully owned and operated by Deimos Imaging (DMI), an UrtheCast company. Deimos-1 satellite was successfully launched on 29 July 2009 from the Baikonur Launch Complex (Kazakhstan) in the Russian-Ukrainian Dnepr launcher. The mission is fully dedicated to Earth Observation and captures images all around the world. Thus, currently the Deimos-1 system provides capabilities well above and beyond the design goals.
The payload is a three-band multispectral imager system with 22m Ground Sample Distance (GSD) at nominal altitude (663 km) with 625 km swath, 8 or 10 bits radiometric depth available. Imager delivers data in three spectral bands, very close to the Near-Infrared (NIR), Red (R) and Green (G) bands in the Landsat series of US satellites. The satellite payload is a dual bank linear CCD push broom imager, so that banks are mounted at an angle to provide a wide imaging swath, one of the most characteristics Deimos-1 features.

Instrument:... read more

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UK-DMC2 is based on the SSTL-100 satellite platform and was launched in 2009 for the commercial imaging company, DMCii (a subsidiary of SSTL). It provides high resolution (22m) imagery from a sun-synchronous orbit over very large areas (650km swath, 2000km along track), with a daily revisit to global targets.
The UK-DMC2 satellite carries a multispectral optical instrument with a spatial resolution of 22 m with three spectral bands (red, green, NIR) and a wide swath of more than 600 km. UK-DMC2 operates within the Disaster Monitoring Constellation, the first Earth observation constellation of low cost small satellites providing daily images for applications including global disaster monitoring. The Disaster Monitoring Constellation is coordinated by DMC International Imaging Ltd (DMCii) for disaster response within the International Charter: Space & Major Disasters.

Instrument: SLIM6-22
- compact imager with 22m GSD at 686km orbital height... read more

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