Fine-sediment Dynamics in the Mekong River Estuary, Vietnam

Wolanski, Eric; Huan, Nguyen Ngoc; Dao, Le Trong; Nhân, Nguyễn Hữu; Thủy, Nguyễn Ngọc

doi:10.1006/ecss.1996.0088

Cited by 187 publications

(132 citation statements)

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“…Using this method, the salt wedge intruded 11 km upstream of section A on the high-flow greater flood. This location, some 30 km upstream of the mouth (river km 0; Figure 1) and 8 km downstream of B, is farther landward than the location of maximum salinity intrusion found by Wolanski et al [1996]. That study took place in November, when Song Hau discharge is on average about 10% higher than during our study period, suggesting that, despite extensive dam construction in the interim [Xue et al, 2011], the high-flow salinity intrusion length has not changed dramatically in the past 20 years.…”

Section: Velocity Patternsmentioning

confidence: 69%

“…In addition to confirming previously observed seasonal changes of the tidal river and estuarine region of the lower Mekong [Wolanski et al, 1996[Wolanski et al, , 1998], we sought to understand better the tidal-scale dynamics and spatial variability of this system, and how river flow modifies these characteristics. Our objectives in this work are: to quantify the changes in hydrodynamics and sediment transport on multiple temporal and spatial scales; to decompose the residual sediment flux; to determine the contributions of different sediment-transport processes and their variability with discharge; and to discuss the geomorphic implications of the observations.…”

Section: Introductionmentioning

confidence: 81%

“…Typical Song Hau discharge ranges seasonally from 5000 to 12,000 m 3 s 21 at Can Tho, Vietnam, 35 km upstream of the landward extent of our study area (Figure 1). During high flow, freshwater can extend to the mouth of the Dinh An, while during low flow, salt water has been observed to penetrate about 50 km landward of the mouth [Wolanski et al, 1996[Wolanski et al, , 1998Nguyen and Tanaka, 2007;Nguyen et al, 2008], although the river mouth endpoint (i.e., 0 km location) for some of these studies was undefined.…”

Section: Study Regionmentioning

confidence: 99%

“…During a high-flow period in 1993, Wolanski et al [1996] encountered saltwedge estuarine conditions where ebb flows were stronger than floods, no along-channel SSC gradient was observed, no turbidity maximum was present, and the river bed was mostly sandy. They further found that deposition and erosion dominated SSC variability and the system exported sediment to the ocean.…”

Section: 1002/2015jc010754mentioning

confidence: 99%

“…The enhanced minimum SSC during high flow suggests that delivery from upstream was considerable, and sediment settling rates were slow in freshwater regions, likely because flocculation of riverine sediment was limited in regions of low salinity. Wolanski et al [1996] posited that advection could be disregarded and variability in the sediment signal during high flow was fully attributable to local erosion and deposition. Although our data similarly show that the (minor) SSC variability is primarily due to local erosion and deposition, the majority of the fine-grained sediment transported during high flow is carried by the river from locations upstream.…”

Section: 1002/2015jc010754mentioning

confidence: 99%

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Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

et al. 2015

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A better understanding of flow and sediment dynamics in the lowermost portions of large‐tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended‐sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high‐seasonal and low‐seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s−1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s−1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr−1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high‐flow sediment export. Exchange‐flow and tidal processes, including local resuspension, were principally responsible for the low‐flow import. The resulting bed‐sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid‐channel islands.

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Section: Velocity Patternsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 81%

Section: Study Regionmentioning

confidence: 99%

Section: 1002/2015jc010754mentioning

confidence: 99%

Section: 1002/2015jc010754mentioning

confidence: 99%

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Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

et al. 2015

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Suspended sediment fluxes in the tidal Ouse, UK

Uncles

Stephens

1999

Hydrol. Process.

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Abstract:A strong turbidity maximum (TM) of suspended particulate matter (SPM) was observed in the upper Humber and lower Ouse during both spring and neap tides of May 1994. Near-bed concentrations within the TM sometimes exceeded¯uid mud levels following slack water periods. SPM within the TM comprised very ®ne-grained material. Its low organic content demonstrated that the SPM was essentially mineral, clastic sediment. Generally, tidal advection of SPM was the dominant¯ux mechanism and the pronounced¯ood±ebb asymmetry in the tidal currents was re¯ected in these¯uxes. However, the presence of¯uid mud near the downestuary margins of the TM on the early ebb resulted in a strong, up-estuary shear¯ux that opposed the ebb-directed advection. This mechanism therefore acted to maintain ®ne sediment in the TM region. SPM concentrations in the in¯owing fresh water at Naburn Weir were much less than those observed within the TM region (5300 mg l À1 compared with 470 000 mg l À1 ). The estimated mean SPM transport into the tidal Ouse across Naburn Weir was about 4 kg s À1 (42 and 511 kg s À1 ) during 1994. In the TM area, the SPM transported during the course of a single spring tide¯ood was roughly equivalent to 30 months of Naburn SPM in¯ows at average 1994 levels. The tidally averaged SPM transport in the TM region was directed into the estuary and, per tide, was roughly equivalent to three months of Naburn inputs.

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A review of tropical cyclone‐generated storm surges: Global data sources, observations, and impacts

Needham

Keim

Sathiaraj

2015

Reviews of Geophysics

241

115

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Tropical cyclone-generated storm surges are among the world's most deadly and destructive natural hazards. This paper provides the first comprehensive global review of tropical storm surge data sources, observations, and impacts while archiving data in SURGEDAT, a global database. Available literature has provided data for more than 700 surge events since 1880, the majority of which are found in the western North Atlantic (WNA), followed by Australia/Oceania, the western North Pacific (WNP), and the northern Indian Ocean (NIO). The Bay of Bengal (BOB) in the NIO consistently observes the world's highest surges, as this subbasin averages five surges ≥5 m per decade and has observed credible storm tide levels reaching 13.7 m. The WNP observes the highest rate of low-magnitude surges, as the coast of China averages 54 surges ≥1 m per decade, and rates are likely higher in the Philippines. The U.S. Gulf Coast observes the second highest frequency of both high-magnitude (≥5 m) and low-magnitude (≥1 m) surges. The BOB observes the most catastrophic surge impacts, as 59% of global tropical cyclones that have killed at least 5000 people occurred in this basin. The six deadliest cyclones in this region have each killed at least 140,000 people, and two events have killed 300,000. Storm surge impacts transportation, agriculture, and energy sectors in the WNA. Oceania experiences long-term impacts, including contamination of fresh water and loss of food supplies, although the highest surges in this region are lower than most other basins.

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Fine-sediment Dynamics in the Mekong River Estuary, Vietnam

Cited by 187 publications

References 0 publications

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

Sediment dynamics in the lowerMekongRiver: Transition from tidal river to estuary

Suspended sediment fluxes in the tidal Ouse, UK

A review of tropical cyclone‐generated storm surges: Global data sources, observations, and impacts

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