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

Data Source

Publishing institution: Joint Research Center, European Commission (JRC)
Drought Watch is an interactive webmap which provides drought monitoring and early warning information for the Danube region in Europe.
Publishing institution: Canadian Space Agency (CSA)

News

UN-SPIDER mission team at the Ethiopian Space Science and Technology Institute (ESSTI).

Timely and reliable information about precipitation, soil moisture and vegetation health provide essential insights for early detection of drought. Space-based information, which helps monitor these parameters, is a central data source for effective drought early warning systems.

Upon the request of the Government of Ethiopia, UN-SPIDER is carrying out a Technical Advisory Mission (TAM) to Addis Ababa from 26 to 30 August to support the country in making use of the benefits of space technology for drought early warning. The team of experts from UN-SPIDER and the Centre for Remote Sensing of Land Surfaces (... read more

Publishing date: 28/08/2019
Regional Support Offices mentioned:

Advisory Support

As part of the technical advisory support it provides to countries worldwide, UN-SPIDER carried out an Institutional Strengthening Mission to Nepal from 17 to 21 December 2018 upon the request of the government. The mission was a follow-up activity to the Technical Advisory Mission (TAM) to Nepal in July 2017 that assessed use of space-derived information in all aspects of disaster management and offered recommendations and action plan to strengthen the disaster risk management and emergency response in the country. The TAM and ISM were conducted with support from the Ministry of Home Affairs (MoHA). The Nepal GIS Society also offered support in organizing the programme.

Mission dates: 17/12/2018 to 21/12/2018

Event

This short tutorial is the first video (Part 1) of the “Getting Started with MODIS Version 6 -Vegetation Indices Data” video series.

This video focuses on the National Aeronautics and Space Administration’s (NASA) Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Version 6 Vegetation Indices data distributed by NASA’s Land Processes Distributed Active Archive Center (LP DAAC).

In this short tutorial, we will cover the MODIS Version 6 Vegetation Indices data products, improvements in Version 6 products over Version 5 products, and how to search for and download these data using the NASA Earthdata Search Client data access tool To learn more about MODIS Version 6 Vegetation Indices data and other data products distributed by the LP DAAC please visit... read more

This short tutorial video focuses on the National Aeronautics and Space Administration’s (NASA) Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Version 6 Vegetation Indices data distributed by NASA’s Land Processes Distributed Active Archive Center (LP DAAC).

In this video, we'll provide you information about the MODIS Version 6 Vegetation Indices data products, discuss the scale factor of the data and other data values, and show you how to use a color map to visualize the Normalized Difference Vegetation Index (NDVI). In addition, the tutorial will also cover how to find Vegetation Indices resources on the LP DAAC website.

To learn more about NASA MODIS Version 6... read more

Getting Started with MODIS Version 6 Vegetation Indices Data

This video focuses on the National Aeronautics and Space Administration’s (NASA) Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Version 6 Vegetation Indices data distributed by NASA’s Land Processes Distributed Active Archive Center (LP DAAC).

This short tutorial is the 3rd video in the series and will provide the viewer with information about MODIS Vegetation Indices quality information, including how to decode quality bits, tools for working with quality data, and where to find additional information.

To learn more about MODIS Version 6 Vegetation Indices data and other data products distributed by the LP DAAC visit... read more

Sentinel-2 is the high-resolution optical satellite of ESA and the EU. The images have a resolution of 10 to 20 meters, higher than Landsat, and, as always with the Copernicus programme, the data are free and open.
In this tutorial, we’ll download an image, make it look good, and create maps of vegetation indices to show the general health of crops and other vegetation. This is a basic tutorial, but even for those with experience in remote sensing, it is a good starting point for working with Sentinel-2 data.

Time to go... read more
Remote Sensing of Drought

Prolonged drought can result in economic, environmental, and health-related impacts. In this webinar, participants will learn how to monitor drought conditions and assess impacts on the ecosystem using precipitation, soil moisture, and vegetation data. The training will provide an overview of drought classification, as well as an introduction to web-based tools for drought monitoring and visualization. Lectures will be followed by hands-on demonstrations of data access and visualization.

Learning Objectives: 

By the end of the training, participants will be able to:

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