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).

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SAM Satellite

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The mission goal of GF-2 to implement sub-meter level, high geographical accuracy Earth surface imaging, promoting application of CHEOS satellites and its social and economic benefits, meanwhile to make breakthrough in key technologies like fast roll and high stable attitude control, long focal length large f-number, lightweight camera design and long life bus design, enhancing China's civilian imaging satellite abilities and reliability.

Instrument: PMC-2 (PAN and Multispectral Camera Suite-2)
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Launch date:
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SPOT-7 is a high-resolution wide-swath imaging spacecraft built and operated by Airbus Defence and Space taking over the majority of Spot Image after the government support of the SPOT program was terminated. SPOT-6 – launched in 2012 – and SPOT-7 are identical spacecraft, based on the AstroSat-250 satellite bus and use the NAOMI (New AstroSat Optical Modular Instrument) payload to acquire optical imagery to ensure the continuity of SPOT data, building on experience gained through previous missions, particularly SPOT-5 that launched in 2002.
The SPOT-7 spacecraft is built for a ten-year mission featuring two NAOMI cameras to cover a 60-Kilometer ground swath, 120km using single-pass mosaic imaging. Overall, the satellite can achieve a resolution of two meters in panchromatic and eight meters in multispectral mode covering the visible and near-infrared spectral bands.

Instrument: 2x NAOMI (New AstroSat Optical Modular Instrument)
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Launch date:
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Launched in June 2014 with an expected life-time of more than 7 years, Deimos-2 is an agile, high resolution satellite that became the only European fully-private satellite capable of providing sub-metric multispectral imagery. From a 620-km ascending sun-sync orbit, it has a 12/24-km swath (depending on the imaging mode), stereo-par capability and ±45º off-nadir tilting capacity. Its multispectral camera has a panchromatic and 4 spectral bands (R,G,B,NIR), at 10 bits. This allows Deimos-2 to provide 75-cm pan-sharpened imagery.

Deimos-2 was designed to provide a cost-effective and highly responsive service to cope with the increasing need of fast access to sub-metric imagery. As evidence of this, it provides near-real time image tasking, downloading, processing and delivery to the end user. It has a collection capacity of more than 150,000 km2/day with a two-day average revisit time worldwide. The whole Deimos-2 ground segment has been completely developed in-house by... read more

Launch date:
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The state-of-the-art L-band Synthetic Aperture Radar (SAR) aboard ALOS-2, which is an active microwave radar using the 1.2 GHz frequency range, which, in responding to society's needs, has enhanced performance. The SAR is capable of observing day and night, and in all weather conditions.

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Sentinel-1 will work in a pre-programmed operation mode to avoid conflicts and to produce a consistent long-term data archive built for applications based on long time series.
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Launch date:
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Launch date:
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KOMPSAT-5 is an earth observation satellite equipped with Korea's first all-weather SAR.
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As the SAR image can supplement the optical camera, which can record only the visible light spectrum, it is utilized in mutual supplementary operations with the high-resolution optical images of KOMPSAT-3 and KOMPSAT-3A.
KOMPSAT-5 observes the Korean Peninsula four times a day. The transmitted image data are used for public safety, natural disaster forecasts, land/resource management and environmental monitoring.

The primary mission of the KOMPSAT-5 system is to provide high resolution mode SAR images of 1 meter resolution, standard mode SAR images of 3 meter resolution and wide swath mode SAR images of 20 meter resolution with viewing conditions of the incidence... read more

Launch date:
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Resurs-P1 is meant to replace the Resurs-DK, a previous generation spacecraft, which was launched on June 15, 2006.

Resurs-P carries the Geoton-L1 hyperspectral imaging payload as the main imaging instrumet. The optics have an apperture of 0.5 m and provides images with a ground resolution of 1.0 m in panchromatic mode and a resolution of 3 to 4 m in color mode. The Geoton-L1 system has 7 passbands and a 216-channel hyperspectral imager.

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Launch date:
25/06/2013

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Launched on 7 May 2013... read more

Launch date:
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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.

Instruments:
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WFI (Wide Field Imager)

Launch date:
26/04/2013

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