Sustainability Nexus Analytics, Informatics, and Data (AID) Programme
DROUGHT
WHY DOES DROUGHT
MATTER?
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Globally, all businesses are dependent on water. No sector is protected against operational disruption in the face of prolonged droughts. The top five critical sectors within the global economy that would be severely affected are agriculture, banking and insurance, energy and utilities, fast-moving customer goods, and manufacturing & distribution services [link].
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Drought is a global disaster. By 2050, the global agricultural sector could see USD 332 billion in losses due to drought and extreme rainfall [link].
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In 2021 alone, drought conditions in California resulted in USD 1.7 billion in direct and indirect costs, more than 14,000 lost jobs, and nearly 162,000 hectares of fallowed farmland [link].
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Nearly 50% of all emergency food aid to Africa is due to drought [link].
WHY A NEXUS APPROACH?
Drought is a hazard to nature and a global issue. It is a "creeping phenomenon" since we can’t see it ignite, like a fire, or predict where it is likely to touch down, as we do a tornado. Its slow-moving behavior accumulates increasingly over weeks, months, and even years as moisture deficits propagate through ecosystems and the hydrological cycle. If not prevented and appropriately mitigated, drought can lead to destruction that may even include loss of life [link]. Drought is a complex phenomenon at the intersection of climatology, meteorology, hydrology, ecology, agronomy, economics, and even politics. Such multidisciplinary nature of drought” poses a challenge to anyone seeking to fully comprehend the impacts and dynamics of such events. Scientists have tried to dismantle the complexity of drought by breaking it down into various categories such as agricultural drought, hydrologic drought, meteorological drought, snow drought (or deficits in snow water equivalent, SWE), socio-economic drought, and anthropogenic drought. While more attention has been given to agricultural and meteorological droughts, the least attention has been given to social and cultural aspects concerning the human experience of drought. While historically, periods of relative dryness and moisture have always occurred, anthropogenic climate change has added to the cost of recovering from this slow-moving disaster and has added a substantial negative impact on the Earth’s systems leading to more severe and longer droughts, such as the ones that recently descended on California and Syria.
Droughts always have and will continue to occur, but our actions are almost certainly making drought conditions worse, with profound implications for ecological and human health. For example, land use and agriculture practices lead to degradation and groundwater depletion, and fossil fuel-burning industries cause excessive greenhouse gas emissions, exacerbating dangerous drought conditions.
As water will remain a critical resource to manage in most regions of the world, the quality of life for humans and non–humans will be determined by how we understand the global nexus of players that feed into drought. By acknowledging and managing drought causes through multidisciplinary scientific studies and commitment to environmental justice, we can achieve a sustained global ecosystem and build toward a more educated and rational world to protect Planet Earth.
AID TOOLS
Variables often used to monitor drought conditions are precipitation, temperature, humidity, soil moisture, vegetation indices, evaporation, surface water, groundwater storage, and snow depth. Commonly used drought monitoring indices use these variables to track the duration or intensity of drought events:
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Standardized Precipitation Index (SPI)
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Standardized Soil Moisture Index (SSI)
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Standardized Runoff Index (SRI)
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Standardized Groundwater level Index (SGI)
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Standardized Relative Humidity Index (SRHI)
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Standardized Snow Water Equivalent Index (SWEI)
Combined Drought Indicator (CDI) by the European Drought Observatory
The CDI is derived by combining SPI, SMA, and FAPAR Anomaly. The indicator is useful for identifying European regions impacted by agricultural drought. Various database access tools and interactive maps can be accessed through EDO’s CDI portal.
Global Standardized Precipitation Evapotranspiration Index (SPEI)
Offers long-time drought conditions at the global scale, with a 0.5 degrees spatial resolution and a monthly time resolution. Its multi-scale character provides SPEI time scales between 1 and 48 months. Currently, it covers the period between January 1901 and December 2020.
NOAA Global Drought Information System
Provides access to several global drought monitoring products, including the North American Drought Monitor (NADM), the EDO Combined Drought Indicator (CDI), the GPCC Global Drought Index (DI), the GPCC Global Standardized Precipitation Evapotranspiration Index (SPEI), the MERRA2 Evaporative Demand Drought Index (EDDI), the GPCC Standardized Precipitation Index (SPI), the CMORPH Daily Standardized Precipitation Index, the MODIS Evaporative Stress Index (ESI), and GRACE-based products.
African Drought Monitor Programme (AFDM)
Originally developed at Princeton University, AFDM is an experimental system for early warning of drought and flood conditions. The system is based on a set of ground, satellite, and modeled datasets combined to provide a consistent picture of hydrological conditions close to real-time, as well as forecasts out to 7 days for floods and 6 months for drought. The page also links to some country-specific (i.e., Zimbabwe, Mozambique, Namibia, South Africa, and Malawi) drought and flood monitor tools.
GitHub Climate and Drought Indices Code in Python
Sponsored by NOAA, NCEI, and NIDIS, this project is developed by independent scientific programmer James Adams on his GitHub account. It contains Python algorithms of various climate indices (SPI, SPEI, PET, PNP, etc.), which provide a geographical and temporal picture of the severity of precipitation and temperature anomalies useful for climate monitoring and research. Several experimental algorithms for other indices (PDSI, scPDSI, PHDI, Z-Index, and PMDI) are also presented.
Global Snow Drought Data Set
This collection contains information about snow droughts (or deficits in snow water equivalent, SWE) and their characteristics (e.g., duration and intensity) across the globe. The snow drought information is derived using SWE from a global reanalysis over 1980-2018, which was standardized using methods described in Huning and AghaKouchak (2020a). This data provide the 3-month standardized snow drought index (SWEI) fields used to characterize and monitor snow droughts in the NetCDF4 (classic) format. Changes in snow drought characteristics for seven study regions worldwide: the western United States, Europe, Hindu Kush, and Central Asia, greater Himalayas, eastern Russia, extratropical Andes, and Patagonia are also provided in an ASCII file.
NOAA STAR Global Vegetation Health Product
Global and Regional Vegetation Health (VH) is a NOAA/NESDIS system for monitoring vegetation Health (VHI), Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Soil Saturation Index (SSI), No noise Normalized Difference Vegetation Index (SMN), No noise Britheness Temperature (SMT), Fire Risk Index (FRI), Drought (D), Malaria, ENSO/Land Ecosystem INteraction, Time Series, Start of the growing season, and Ecosystem Resources. The VH products from AVHRR are from 1981 to the present, with 4km resolution and 7-day composite, and the VH products from VIIRS data are from 2012 to the present and with 1km resolution and 7-day composite.
North American Drought Monitor (NADM)
NADM is an extension of the U.S. Drought Monitor (USDM) program and a cooperative effort between drought experts in Canada, Mexico, and the United States to monitor drought across the continent on an ongoing basis. NADM monthly maps are produced through data sources from consultations with federal, provincial, regional, and academic scientists to establish a single drought index based on the five categories of the intensity of drought.
Get to Know AID Members
You can consult with the AID group leader or any members for your regional, national, and global datasets, tools, and analytics projects and questions.
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