Satellite drought-watch improved
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New satellite methods offer stronger tools for detecting droughts from space.
A recent study led by the Military University of Technology in Poland and Griffith University in Australia demonstrates an enhanced approach for monitoring droughts by integrating Global Positioning System (GPS) and Gravity Recovery and Climate Experiment (GRACE) data.
The research, which tested the method in the Amazon Basin and California’s Central Valley, shows satellites' improved ability to monitor hydrological droughts more accurately.
While traditional satellite systems like GRACE and GPS have been crucial in tracking global freshwater changes, they have faced challenges.
GRACE is reliable for large-scale data but struggles at local levels, while GPS data is vulnerable to technical and environmental disruptions, including ground instability or tidal errors.
Dr Christopher Ndehedehe, an ARC DECRA Fellow at Griffith's Australian Rivers Institute and co-author of the study, said that these systems also have difficulty detecting sudden droughts, leading to potential underestimations of frequency and severity.
To address this, researchers developed a new technique that merges GPS and GRACE vertical displacement data.
This combined approach offers more accurate, real-time information for drought monitoring, supporting timely decision-making.
“By combining GPS and GRACE data, the novel drought indicator enhances our ability to track short-term drought events more accurately,” Dr Ndehedehe says.
Central to this method is the Multivariate Drought Severity Index (MDSI), which uses advanced statistical techniques called Frank copulas to blend data from the two satellite systems.
The MDSI detected previously unnoticed drought events and their impacts on freshwater systems, while also showing strong agreement with other drought indicators like river discharge data and the Enhanced Vegetation Index.
Dr Artur Lenczuk, lead author of the study, has highlighted the need for improved drought tracking tools, especially in areas with variable climates.
“Monitoring the onset and progression of droughts is essential for water resource management,” he said.
The researchers believe this new method represents a significant step toward better global water management as climate change drives more frequent and severe droughts.