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Intensifying saline water intrusion and drought in the Mekong Delta: From physical evidence to policy outlooks
Citation
Ho, H. L., Doan, V. B., Park, E., Sangam Shrestha, Tran, D. D., Vu, H. S., Nguyen, H. T. T., Nguyen, P. M., & Seijger, C. (2021). Intensifying saline water intrusion and drought in the Mekong Delta: From physical evidence to policy outlooks. Science of The Total Environment, 757, Article 143919. https://doi.org/10.1016/j.scitotenv.2020.143919
Author
Ho, Huu Loc
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Doan, Van Binh
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Sangam Shrestha
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Tran, Duc Dung
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Vu, Hai Son
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Nguyen, Hoang Thu Truc
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Nguyen, Phuong Mai
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Seijger, Chris
Abstract
This paper assesses the recently intensified saline water intrusion (SI) and drought in the Vietnamese Mekong Delta (VMD). While the existing literature predominantly points the cause of drought to the hydropower dams in the upstream of the Mekong Basin, we contribute new physical evidence of the intensification of saline water intrusion (through backwater effect) in the VMD caused by three anthropogenic drivers: riverbed incision (due to both riverbed mining and dam construction), sea level rise and land subsidence. Thereupon, we highlight that it is critical to not underestimate the impacts from the localized factors, especially the riverbed-mining which can incise the channel by up to 15 cm/year and amplify the salinity intrusion. Our analysis is based on the extensive sets of hourly-to-daily hydrological time series from 11 gauge stations across the VMD. First, several signs of significantly increased tidal amplification (up to 66%) were revealed through the spectral analysis of the hourly water level data. This trend was further validated through the changes in slopes of the rating curves at the tidal zones, implying the relationships between the shift of the backwater effects on the rivers in VMD and the lowered water levels caused by the riverbed incision. Finally, we introduce a novel approach using the annual incision rates of the riverbed to compare four SI driving factors in terms of their relative contributions to the balance between fresh and saline water in the VMD.
Publisher
Elsevier
Journal
Science of the Total Environment
Grant ID
MOE Academic Research Fund (Grant no.: AcRF Tier1 RT 06/19)
Start-up Grant for New Assistant Professor (Grant no.: SUG-NAP EP3/19)
Funding Agency
Ministry of Education, Singapore
National Research Foundation, Singapore