Geographic Extent of Flash Droughts Across the Seven Climatic Sub-regions of Vietnam
Main Article Content
Abstract
This study analyzed the spatio-temporal characteristics of flash droughts across seven climatic sub-regions of Vietnam using ERA5 soil moisture data at three depths (7 cm, 28 cm, and 100 cm) over the period 1961 - 2020. The results reveal notable differences in flash drought occurrence between regions and across soil depths, with the shallowest layer (D7) showing the highest sensitivity to dry conditions. Although variations exist in absolute values, all results from three criteria consistently identify high flash drought frequency and duration in regions R1, R2, R4, and R7. Flash droughts primarily occur during the rainy season: JJA (June - August) in the northern regions (R1 - R3) and SON (September - November) in the southern regions (R4 - R7). Notably, flash droughts tend to occur on a broad spatial scale in sub-regions R1 - R3 and R7, where approximately 60% of the identified events affected more than 50% of the regional area, based on D7 and D28 criteria. These findings provide a scientific basis for selecting relevant variables and constructing appropriate input datasets for future flash drought forecasting and early warning models.
Keywords:
Geographic extent, flash droughts, Vietnam.
References
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[2] N. M. Nguyen, M. Choi, Delving into Flash Droughts in Vietnam During the Last Two Decades Using the Standardized Evaporative Stress Ratio, J. Hydrol., Vol. 630, 2024, pp. 130669,
https://doi.org/10.1016/j.jhydrol.2024.130669.
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Vol. 23, 2022, pp. 275-289,
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https://doi.org/10.1088/1748-9326/ab2103.
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https://doi.org/10.1029/2021wr030612.
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pp. e2020GL091901,
https://doi.org/10.1029/2020GL091901.
[16] T. Gerken, G. T. Bromley, B. L. Ruddell, S. Williams, P. C. Stoy, Convective Suppression Before and During the United States Northern Great Plains Flash Drought of 2017, Hydrol. Earth Syst. Sci., Vol. 22, 2018, pp. 4155–4163.
[17] R. Singh, V. Mishra, Atmospheric and Land Drivers of Streamflow Flash Droughts in India, J. Geophys. Res. Atmos., Vol. 129, 2024,
pp. e2023JD040257,
https://doi.org/10.1029/2023JD040257.
[18] Y. Wang, X. Yuan, Land-Atmosphere Coupling Speeds up Flash Drought Onset, Sci. Total Environ., Vol. 851, 2022, pp. 158109,
https://doi.org/10.1016/j.scitotenv.2022.158109.
[19] C. Wang, C. Deser, J. Y. Yu, P. DiNezio, A. Clement, El Niño and Southern Oscillation (ENSO): A Review, in: Coral Reefs of the Eastern Tropical Pacific: Persistence and Loss in a Dynamic Environment, Springer, 2017, pp. 85-106.
[20] X. Jiang, Á. F. Adames, D. Kim, E. D. Maloney, H. Lin, H. Kim, et al., Fifty Years of Research on the Madden - Julian Oscillation: Recent Progress, Challenges, and Perspectives, J. Geophys. Res. Atmos., Vol. 125, 2020, pp. e2019JD030911,
https://doi.org/10.1029/2019jd030911.
[21] A. Pachore, R. Remesan, J. Kuttippurath, Flash Drought Teleconnection with the Large-Scale Climate Drivers in the Homogeneous Rainfall Regions of India, Int. J. Climatol., Vol. 45, 2025, pp. e8711, https://doi.org/10.1002/joc.8711.
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[26] F. D. Noguera, S. M. V. Serrano, Characteristics and Trends of Flash Droughts in Spain, 1961 - 2018, Ann. N. Y. Acad. Sci., Vol. 1472, 2020,
pp. 155 - 172.
[27] K. C. Mo, D. P. Lettenmaier, Precipitation Deficit Flash Droughts over the United States, J. Hydrometeorol., Vol. 17, 2016, pp. 1169 - 1184,
https://doi.org/10.1175/jhm-d-15-0158.1.
[28] X. Yuan, L. Wang, P. Wu, P. Ji, J. Sheffield, M. Zhang, Anthropogenic Shift Towards Higher Risk of Flash Drought over China, Nat. Commun.,
Vol. 10, 2019, pp. 12692,
https://doi.org/10.1038/s41467-019-12692-7.
[29] Y. Zhang, Q. You, G. Mao, C. Chen, X. Li, J. Yu, Flash Drought Characteristics by Different Severities in Humid Subtropical Basins: A Case Study in the Gan River Basin, China, J. Climate, Vol. 34, 2021, pp. 7337-7357,
https://doi.org/10.1175/jcli-d-20-0596.1.
[30] L. Chen, T. W. Ford, P. Yadav, The Role of Vegetation in Flash Drought Occurrence: A Sensitivity Study Using Community Earth System Model Version 2, J. Hydrometeorol., Vol. 22, 2021, pp. 845-857, https://doi.org/10.1175/jhm-d-20-0214.1.
[31] L. Cheng, M. Hoerling, A. AghaKouchak, B. Livneh, X. W. Quan, J. Eischeid, How Has Human-Induced Climate Change Affected California Drought Risk?, J. Climate, Vol. 29, 2016, pp. 111-120,
https://doi.org/10.1175/JCLI-D-15-0260.1.
[32] J. Sheffield, G. Goteti, F. Wen, E. F. Wood, A Simulated Soil Moisture-Based Drought Analysis for the United States, J. Geophys. Res., Vol. 109, 2004, pp. D24108,
https://doi.org/10.1029/2004JD005182.
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https://doi.org/10.21203/rs.3.rs-267288/v1.
[34] D. Q. Nguyen, J. Renwick, J. McGregor, Variations of Surface Temperature and Rainfall in Vietnam from 1971 to 2010, Int. J. Climatol.,
Vol. 34, 2014, pp. 249-264,
https://doi.org/10.1002/joc.3684.
[35] P. T. T. Nga, P. T. Ha, V. T. Hang, Satellite-Based Regionalization of Solar Irradiation in Vietnam by K-Means Clustering, J. Appl. Meteor. Climatol., Vol. 60, 2021, pp. 391-402,
https://doi.org/10.1175/JAMC-D-20-0070.1.
[36] H. P. Thanh, L. Thi, H. Phan, A. H. Fink, R. V. D. Linden, T. P. Van, Heatwaves in Vietnam: Characteristics and Relationship with Large-Scale Climate Drivers, Int. J. Climatol., Vol. 44, 2024, pp. 4725-4740, https://doi.org/10.1002/joc.8606.
[37] J. I. Christian, J. B. Basara, E. D. Hunt, J. A. Otkin, J. C. Furtado, V. Mishra, X. Xiao, R. M. Randall, Global Distribution, Trends, and Drivers of Flash Drought Occurrence, Nat. Commun., Vol. 12, 2021, pp. 1-11,
https://www.nature.com/articles/s41467-021-26692-z (accessed on: August 15th, 2025).
[38] T. Parker, A. Gallant, M. Hobbins, D. Hoffmann, Flash Drought in Australia and Its Relationship to Evaporative Demand, Environ. Res. Lett., Vol. 16, 2021, pp. 064033.
[39] J. Shah, V. Hari, O. Rakovec, Y. Markonis, L. Samaniego, V. Mishra, M. Hanel, C. Hinz, R. Kumar, Increasing Footprint of Climate Warming on Flash Drought Occurrence in Europe, Environ. Res. Lett., Vol. 17, 2022, pp. 064017.
[40] M. S. Saharwardi, W. U. Hassan, H. P. Dasari, Y. Abualnaja, I. Hoteit, Enhanced Flash Droughts in Recent Decades over the Arabian Peninsula, J. Hydrol. Reg. Stud., Vol. 61, 2025, pp. 102696,
https://doi.org/10.1016/j.ejrh.2025.102696.