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

Event

Solar-induced Fluorescence Map. Image: NASA

This introductory webinar will cover the fundamentals of Solar Induced Fluorescence (SIF) and LIDAR, their applications, and an overview of different satellite data sources that are openly available. In addition, it will also include a step-by-step guide on how to access, open, and interpret SIF and LIDAR data.

SIF is a relatively new satellite retrieval, providing a direct measurement related to plant photosynthetic activity. It serves as a strong proxy to gross primary production (GPP), capturing dynamic responses of vegetation to stressors such as drought and temperature.

LIDAR is a system that illuminates a target and measures distance through the time taken for a pulse to reflect back to the sensor. LIDAR can be used to generate topography and vegetation height maps and retrieve digital elevation data necessary for flood modeling and vulnerability, along with risk analysis. They are valuable datasets for post-disaster assessment of debris deposition, vegetation... read more

Data Source

Population Density Map. Image: Facebook Connectivity
Publishing institution: Facebook Connectivity Lab, Center for International Earth Science Information Network (CIESIN) - Columbia University
Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.
Population Density Map. Image: Facebook Connectivity
Publishing institution: Facebook Connectivity Lab, Center for International Earth Science Information Network (CIESIN) - Columbia University
Facebook Connectivity Lab in collaboration with the Center for International Earth Science Information Network (CIESIN) at Colombia University combines machine vision AI with satellite imagery and census information to create population density maps. With the integration of demographic information, specifically related to age and gender, these maps collectively provide information on both the location and the demographic of a population in a certain country. The population density maps cover the majority of countries around the world.

Advisory Support

Mission dates: 01/09/2020 to 30/09/2020
Regional Support Offices mentioned:
Mission dates: 12/08/2020 to 22/12/2020
Regional Support Offices mentioned:

News

The United Nations Office for Outer Space Affairs (UNOOSA) and the National Aeronautics and Space Administration of the United States Government (NASA) signed a landmark Memorandum of Understanding (MoU) on 17 December 2020 pledging cooperation in areas of science and technology to support the peaceful uses of outer space.

The MoU brings together NASA's wealth of open-source spacecraft data, tools, and expertise and UNOOSA's unique position as the only UN entity dedicated to outer space affairs, to expand global opportunities to leverage the benefits of space. The partners will design capacity-building programmes, particularly for institutions in countries that do not yet have or that are developing space capabilities, to help them access space.

Together, UNOOSA and NASA will develop ways to leverage the Artemis programme as part of UNOOSA's Access to Space 4 All Initiative, which offers opportunities for international researchers and institutions, especially in... read more

Publishing date: 11/01/2021
Snapshot of the SIRIS platform in action. Image: Mexican Space Agency (AEM)

In collaboration with the National Commission for Space Activities (CONAE) of Argentina, the Mexican Space Agency (AEM) recently launched a digital platform to improve the integration of satellite data for environmental monitoring in Latin America. The Comprehensive Regional Satellite Information System (SIRIS) provides access to satellite information in order to enhance decision-making and facilitate disaster management.

The SIRIS platform provides access to satellite imagery for different areas. The platform supplies information on the agriculture and forestry sector to better monitor the impact of natural disasters on agricultural production and woodland. It also offers up-to-date and archived data on fires to strengthen early warning and build long-term resilience. On floods, information provided by SIRIS indicates the water level to improve damage evaluation of the impacted area and facilitate humanitarian relief. In... read more

Publishing date: 20/12/2020

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