Oceanography The Official Magazine of
The Oceanography Society
Volume 30 Issue 03

View Issue TOC
Volume 30, No. 3
Pages 22 - 33

OpenAccess

How Tidal Processes Impact the Transfer of Sediment from Source to Sink: Mekong River Collaborative Studies

By Andrea S. Ogston , Mead A. Allison, Robin L. McLachlan, Daniel J. Nowacki, and J. Drew Stephens 
Jump to
Article Abstract Citation References Copyright & Usage
Article Abstract

Significant sediment transformation and trapping occur along the tidal and estuarine reaches of large rivers, complicating sediment source signals transmitted to the coastal ocean. The collaborative Mekong Tropical Delta Study explored the tidally influenced portion of the Mekong River to investigate processes that impact mud- and sand-sized sediment transport and deposition associated with varying fluvial and marine influences. Researchers participating in this 2014–2015 project found that as sand and mud progress down the tidal portion of the river, sands in suspension can settle during reduced or slack flows as river discharge becomes progressively more affected by tides in the seaward direction. Consequently, deposits on the tidal river bed are connected to sand transport in the channel. In contrast, fine mud particles remain in suspension until they reach an interface zone where waters are still fresh, but the downstream saline estuary nonetheless impacts the flows. In this interface zone, as within the estuary, fine particles tend to settle, draping the sand beds with mud and limiting the connection between the bed and suspended sand. In the Mekong system, the interface and estuarine zones migrate along the distributary channels seasonally, resulting in variable trapping dynamics and channel bed texture. Therefore, the signature of fluvial-sediment discharge is altered on its path to the coastal ocean, and the disconnected mud and sand supply functions at the river mouth should result in distinct offshore depositional signatures.

Citation

Ogston, A.S., M.A. Allison, R.L. McLachlan, D.J. Nowacki, and J.D. Stephens. 2017. How tidal processes impact the transfer of sediment from source to sink: Mekong River collaborative studies. Oceanography 30(3):22–33, https://doi.org/10.5670/oceanog.2017.311.

References

Allison, M.A., C.A. Nittrouer, A.S. Ogston, J.C. Mullarney, and T.T. Nguyen. 2017. Sedimentation and survival of the Mekong Delta: A case study of decreased sediment supply and accelerating rates of relative sea level rise. Oceanography 30(3):98–109, https://doi.org/​10.5670/oceanog.2017.318.

Allison, M.A., H.D. Weathers III, and E.A. Meselhe. In press. Bottom morphology in the Song Hau distributary channel, Mekong River Delta, Vietnam. Continental Shelf Research, https://doi.org/10.1016/​j.csr.2017.05.010.

Brunier, G., E.J. Anthony, M. Goichot, M. Provansal, and P. Dussouillez. 2014. Recent morphological changes in the Mekong and Bassac river channels, Mekong delta: The marked impact of river-bed mining and implications for delta destabilization. Geomorphology 224:177–191, https://doi.org/10.1016/j.geomorph.2014.07.009.

Darby, S.E., C.R. Hackney, J. Leyland, M. Kummu, H. Lauri, D.R. Parsons, J.L. Best, A.P. Nicholas, and R. Aalto. 2016. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity. Nature 539:276–279, https://doi.org/10.1038/nature19809.

Eidam, E.F., C.A. Nittrouer, A.S. Ogston, D.J. DeMaster, J.P. Liu, T.T. Nguyen, T.N. Nguyen. In press. Dynamic controls on shallow clinoform geometry: Mekong Delta, Vietnam. Continental Shelf Research, https://doi.org/10.1016/j.csr.2017.06.001.

Fagherazzi, S., K.R. Bryan, and W. Nardin. 2017. Buried alive or washed away: The challenging life of mangroves in the Mekong Delta. Oceanography 30(3):48–59, https://doi.org/​10.5670/oceanog.2017.313.

Goodbred, S.L., and S.A. Kuehl. 1999. Holocene and modern sediment budgets for the Ganges-Brahmaputra river system: Evidence for highstand dispersal to flood-plain, shelf, and deep-sea depocenters. Geology 27(6):559–562, https://doi.org/10.1130/0091-7613(1999)027​<0559:HAMSBF>2.3.CO;2.

Gugliotta, M., Y. Saito, V.L. Nguyen, T.K.O. Ta, R. Nakashima, T. Tamura, K. Uehara, K. Katsuki, and S. Yamamoto. In press. Process regime, salinity, morphological, and sedimentary trends along the fluvial to marine transition zone of the mixed-energy Mekong River delta, Vietnam. Continental Shelf Research, https://doi.org/10.1016/​j.csr.2017.03.001.

Harden, P.O., and A. Sundborg. 1992. The Lower Mekong Basin Suspended Sediment Transport and Sedimentation Problems. Hydroconsult, Uppsala, Sweden.

Kondolf, G.M., Z.K. Rubin, and J.T. Minear. 2014. Dams on the Mekong: Cumulative sediment starvation. Water Resources Research 50(6):5,158–5,169, https://doi.org/10.1002/2013WR014651.

Kummu, M., X.X. Lu, J.J. Wang, and O. Varis. 2010. Basin-wide sediment trapping efficiency of emerging reservoirs along the Mekong. Geomorphology 119(3):181–197, https://doi.org/​10.1016/j.geomorph.2010.03.018.

Liu, J.P., D.J. DeMaster, T.T. Nguyen, Y. Saito, V.L. Nguyen, T.K.O. Ta, and X. Li. 2017. Stratigraphic formation of the Mekong River Delta and its recent shoreline changes. Oceanography 30(3):72–83, https://doi.org/10.5670/oceanog.2017.316.

McLachlan, R.L., A.S. Ogston, and M.A. Allison. In press. Implications of tidally-varying bed stress and intermittent estuarine stratification on fine-​sediment dynamics through the Mekong’s tidal river to estuarine reach. Continental Shelf Research, https://doi.org/10.1016/j.csr.2017.07.014.

Mekong River Commission. 2005. Overview of the Hydrology of the Mekong Basin. Mekong River Commission, Vientiane Lao PDR.

Milliman, J.D., and K.L. Farnsworth. 2011. River Discharge to the Coastal Ocean: A Global Synthesis (2013 ed). Cambridge University Press, 394 pp.

Milliman, J.D., and R.H. Meade. 1983. World-wide delivery of river sediment to the oceans. The Journal of Geology 91:1–21.

Mullarney, J.C., S.M. Henderson, B.K. Norris, K.R. Bryan, A.T. Fricke, D.R. Sandwell, and D.P. Culling. 2017. A question of scale: How turbulence around aerial roots shapes the seabed morphology in mangrove forests of the Mekong Delta. Oceanography 30(3):34–47, https://doi.org/​10.5670/oceanog.​2017.312.

Nguyen, A.D., H.H.G. Savenije, D.N. Pham, and D.T. Tang. 2008. Using salt intrusion measurements to determine the freshwater discharge distribution over the branches of a multi-channel estuary: The Mekong Delta case. Estuarine, Coastal, and Shelf Science 77:433–445, https://doi.org/10.1016/​j.ecss.2007.10.010.

Nittrouer, C.A., S.A. Kuehl, R.W. Sternberg, A.G. Figueiredo Jr., and L.E.C. Faria. 1995. An introduction to the geological significance of sediment transport and accumulation on the Amazon continental shelf. Marine Geology 125(3–4):177–192, https://doi.org/10.1016/0025-3227(95)00075-A.

Nittrouer, C.A., D.J. DeMaster, E.F. Eidam, T.T. Nguyen, J.P. Liu, A.S. Ogston, and P.V. Phung. 2017. The Mekong continental shelf: The primary sink for deltaic sediment particles and their passengers. Oceanography 30(3):60–70, https://doi.org/​10.5670/oceanog.2017.314.

Nowacki, D.J., A.S. Ogston, C.A. Nittrouer, A.T. Fricke, and P.D.T. Van. 2015. Sediment dynamics in the lower Mekong River: Transition from tidal river to estuary. Journal of Geophysical Research: Oceans 120:6,363–6,383, https://doi.org/​10.1002/2015JC010754.

Stephens, J.B., M.A. Allison, D.R. Di Leonardo, H.D. Weathers III, A.S. Ogston, R.L. McLachlan, F. Xing, and E.A. Meselhe. In press. Sand dynamics in the Mekong River channel and export to the coastal ocean. Continental Shelf Research.

Syvitski, J.P.M., and A. Kettner. 2011. Sediment flux and the Anthropocene. Philosophical Transactions of the Royal Society 369:957–975, https://doi.org/​10.1098/rsta.2010.0329.

Ta, T., V. Nguyen, M. Tateishi, I. Kobayashi, S. Tanabe, and Y. Saito. 2002. Holocene delta evolution and sediment discharge of the Mekong River, southern Vietnam. Quaternary Science Reviews 21:1,807–1,819, https://doi.org/10.1016/S0277-3791(02)00007-0.

Tamura, T., Y. Saito, V.L. Nguyen, T.K.O. Ta, M.D. Bateman, D. Matsumoto, and S. Yamashita. 2012. Origin and evolution of interdistributary delta plains: Insights from Mekong River delta. Geology 40(4):303–306, https://doi.org/10.1130/G32717.1.

Wolanski, E., N.N. Huan, L.T. Dao, N.H. Nhan, and N.N. Thuy. 1996. Fine-sediment dynamics in the Mekong River estuary, Vietnam. Estuarine, Coastal, and Shelf Science 43:565–582, https://doi.org/​10.1006/ecss.1996.0088.

Wolanski, E., N.H. Nhan, and S. Spagnol. 1998. Sediment dynamics during low flow conditions in the Mekong River estuary, Vietnam. Journal of Coastal Research 14(2):472–482.

Xing, F., E.A. Meselhe, M.A. Allison, and H.D. Weathers III. In press. Analysis and numerical modeling of the flow and sand dynamics in the lower Song Hau channel, Mekong Delta. Continental Shelf Research.

Copyright & Usage

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.