Flash droughts occur due to rapid depletion of soil moisture (Photo courtesy of Pixabay)
Dr Shuo WANG, Member of the Research Institute for Land and Space (RILS) and Assistant Professor of the Department of Land Surveying and Geo-Informatics at PolyU, and his research teammates find that flash droughts do not appear to be occurring more frequently in most regions of the world, just coming on faster. Approximately 33.64−46.18% of flash droughts develop within 5 days for the period 2000−2020, and there is a significant increasing trend in the proportion of flash droughts with the 5-day onset time globally. Compared with traditional, slowly developing droughts, flash droughts evolve with a relatively fast depletion of soil moisture that may cause an imbalance of ecosystems and agricultural systems.
Flash droughts are most likely to occur in humid and semi-humid regions, including Southeast China, Southeast Asia, East Asia, Amazon Basin, Eastern North America, and Southern South American. Thus, the increasing flash drought risk is overlooked, without any early warning and emergency response measures, posing serious threats to ecosystem protection and sustainable agriculture development. Atmospheric aridity creates a perfect condition for the occurrence of flash droughts, and the joint influence of soil moisture depletion and atmospheric aridity further enhances the rapid onset of flash droughts. In other words, low soil moisture combined with high vapor pressure deficit accelerates the decline in soil moisture through land–atmosphere feedbacks. Thus, Southeast China with strong land– atmosphere coupling is most vulnerable to flash droughts.
The new study contributes to a deeper understanding of the rapid onset development and driving mechanism of flash droughts. Identification of flash drought-prone regions and global hot spots can help policymakers and stakeholders develop flash drought mitigation and risk management strategies. Furthermore, comprehensive assessment of onset development timescales of flash droughts provides insights into the implementation of flash drought forecasts and early warning systems.
The study has been published in Nature Communications at https://doi.org/10.1038/s41467-022-28752-4
| Research Units | Research Institute for Land and Space |
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