What's the difference between a metereological and agricultural drought?
To understand how droughts lead to food insecurity, we must first understand the distinction between meteorological and agricultural droughts.
Meteorological droughts are characterized by a period of low levels of precipitation - such as rainfall or snowfall. They can also be caused by high evapotranspiration rates driven by heatwaves and other temperature extremes. These droughts can vary in intensity and duration across different regions, but they're usually on the order of days or weeks.
Depending on the type of soil and the region, a drought that's prolonged by months or even years can eventually lead to a significant decrease in soil moisture. When crop growth and agricultural productivity are affected by this lack of soil moisture, we start talking about an agricultural drought.
Why are agricultural droughts significant?
“Agricultural drought” is the crucial concept that ties the drought events to food insecurity. Besides reducing crop yields, there are also indirect effects, such as economic stress, conflicts and migrations that can take place because of water scarcity. Communities located in arid semi-arid lands (ASALs) whose livelihood depends on farming are already suffering these effects of agricultural droughts.
How can we measure droughts?
In the past, scientists assessed droughts using meteorological indices, mainly by observing the lack of precipitation. But this methodology lacks accuracy, as meteorological indices miss one important piece of the puzzle: soil moisture. To accurately measure agricultural droughts, it's necessary to observe this key variable.
State-of-the-art satellite technology, such as ECOSTRESS (Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station) is being developed to fill in this gap. ECOSTRESS uses spaceborne imagery and meteorological data to calculate evapotranspiration and the Evaporative Stress Index of the soil. Scientists are now using it as an accurate indication of vegetation health with great results.
What do we do at ITC?
Using hyperspectral information from ECOSTRESS and from the Italian Space Agency’s PRISMA hyperspectral platform, and German Space Agency’s ENMAP, researchers are developing drought monitoring tools to help farmers and pastroalists in arid semi-arid lands (ASALs) of Kenya. ASALs are particularly sensitive to drought. As part of an agile software development process, this tool will be presented to the researchers, technicians and decision-makers who serve the farmers and pastoralists in the region. This project is developed with an EO Africa – Explores Expro+ grant from the European Space Agency along with the partners CNR-IREA, BOKU, University of Milano, and University Milano-Bicocca.
For more information, please contact Dr M.T Michael Marshall
