Water and Suspended Sediment Budgets in the Lower Mekong from High-Frequency Measurements (2009–2016)

Ha, Dong-Soo; Ouillon, Sylvain; Vinh, Giap Van

doi:10.3390/w10070846

Cited by 55 publications

(52 citation statements)

References 73 publications

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“…Therefore, the peak flows at the downstream stations occur in October. These results are consistent with the analysis of Dang et al (2018).…”

Section: Spatio-temporal Distribution Of Water Volume In the Vmdsupporting

confidence: 92%

Flooding in the Mekong Delta: Impact of dyke systems on downstream hydrodynamics

Thanh¹,

Roelvink²,

Wegen³

et al. 2019

Preprint

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Abstract. Building high dykes is a common measure to cope with floods and plays an important role in agricultural management in the Vietnamese Mekong Delta. However, the construction of high dykes cause considerable changes in hydrodynamics of the Mekong River. Therefore, this paper aims to assess the impacts of the high dyke system on water level fluctuation and tidal propagation on the Mekong River branches using a modelling approach. In order to consider interaction between rivers and seas, an unstructured modelling grid was generated, with 1D–2D coupling, covering the Mekong Delta and extending to the East (South China Sea) and West (Gulf of Thailand) seas. The model was manually calibrated for the flood season of the year 2000. To assess the role of floodplains, scenarios consisting of high dykes built in different regions of the Long Xuyen Quadrangle (LXQ), Plains of Reeds (PoR) and TransBassac were carried out. Results show that the percentage of river outflow at Dinh An sharply increases in the dry season in comparison to the flood season while the other Mekong estuarine outflows rise slightly. In contrast, the lateral river flows of the Mekong River system to the seas by the Soai Rap mouth and the LXQ decrease somewhat in the dry season compared to the flood season due to overflow reduction at the Cambodia–Vietnam border. Additionally, the high dykes in the regions that are directly connected to a branch of the Mekong River, not only have an influence on the hydrodynamics in their own branch, but also on other branches because of the connecting channel of Vam Nao. Moreover, the high dykes built in the PoR, LXQ and TransBassac regions are the most important factor for changing water levels at Tan Chau, Chau Doc and Can Tho, respectively. The LXQ high dykes result in an increase of daily mean water levels and a decrease of tidal amplitudes on the Song Tien (downstream of the connecting channel of Vam Nao). A similar interaction is also found for the the PoR high dykes and the Song Hau.

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“…Therefore, the peak flows at the downstream stations occur in October. These results are consistent with the analysis of Dang et al (2018).…”

Section: Spatio-temporal Distribution Of Water Volume In the Vmdsupporting

confidence: 92%

Flooding in the Mekong Delta: Impact of dyke systems on downstream hydrodynamics

Thanh¹,

Roelvink²,

Wegen³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…When integrated over a year, the effect of water demand dwindles in the wet season. Freshwater proportions of Hau and Tien Rivers increase from 40% and 44% in the dry season to approximately 48% and 52%, respectively [59]. Table 5 highlights the major discrepancies in discharge divisions of downstream distributaries between this study and the existing literature.…”

Section: Temporal and Cumulative And Temporal Discharge Divisionmentioning

confidence: 73%

Flow Division Dynamics in the Mekong Delta: Application of a 1D-2D Coupled Model

Eslami

Hoekstra

Kernkamp

et al. 2019

Water

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The Mekong Delta constitutes a complicated multi-channel estuarine system, exchanging water with a delta-wide irrigation system. A 1D–2DH coupled numerical domain is calibrated and validated for water level and discharge during the dry season. This approach benefits from the simplicity of a 1D network within the estuarine and irrigation systems, while maintaining the interaction with the spatial tidal dynamics of the 2DH coastal domain. First, the role of the irrigation system on tidal dynamics is quantified; then, tidal propagation, freshwater budget, and the effect of offshore subtidal water level on discharge division are investigated. The results show that the complex irrigation system, in a friction-like manner, reduces the tidal amplitude up to 25%. The channels aggregate to 1% of the total water volume in the delta, while accommodating up to 10% of the tidal prism. Tidal amplitude reduces upstream, while subtidal water level is highly sensitive to upstream discharge, spring–neap cycles, and wind-generated offshore surge. Although cumulative discharge division within the estuarine network is consistent, temporal discharge division can be significantly sensitive to offshore wind-surge. During the dry season, it can reverse the expected subtidal discharge division within the time-scale of a few days and potentially influence salt intrusion.

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“…( e ) Instantaneous discharge at station My Thuan for the year 2018. Grey dashed line indicates the mean hydrograph for the years 2009–2016 48 . Raw data for water level and discharge was provided by the SRHMC.…”

Section: Hydro- Morpho- and Sedimentological Regime Of The Mekong Rimentioning

confidence: 99%

Sand mining in the Mekong Delta revisited - current scales of local sediment deficits

Jordan

Tiede

Lojek

et al. 2019

Sci Rep

116

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The delta of the Mekong River in Vietnam has been heavily impacted by anthropogenic stresses in recent years, such as upstream dam construction and sand mining within the main and distributary channels, leading to riverbank and coastal erosion. Intensive bathymetric surveys, conducted within the Tien River branch during the dry and wet season 2018, reveal a high magnitude of sand mining activities. For the year 2018, an analysis of bathymetric maps and the local refilling processes leads to an estimated sand extraction volume of 4.64 0.31 Mm/yr in the study area, which covered around 20 km. Reported statistics of sand mining for all of the Mekong’s channels within the delta, which have a cumulative length of several hundred kilometres, are 17.77 Mm/yr for this period. Results from this study highlight that these statistics are likely too conservative. It is also shown that natural sediment supplies from upper reaches of the Mekong are insufficient to compensate for the loss of extracted bed aggregates, illustrating the non-sustainable nature of the local sand mining practices.

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Water and Suspended Sediment Budgets in the Lower Mekong from High-Frequency Measurements (2009–2016)

Cited by 55 publications

References 73 publications

Flooding in the Mekong Delta: Impact of dyke systems on downstream hydrodynamics

Flooding in the Mekong Delta: Impact of dyke systems on downstream hydrodynamics

Flow Division Dynamics in the Mekong Delta: Application of a 1D-2D Coupled Model

Sand mining in the Mekong Delta revisited - current scales of local sediment deficits

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