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

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Volume 30, No. 3
Pages 98 - 109

Sedimentation and Survival of the Mekong Delta: A Case Study of Decreased Sediment Supply and Accelerating Rates of Relative Sea Level Rise

Mead A. Allison Charles A. NittrouerAndrea S. OgstonJulia C. MullarneyThanh T. Nguyen
Article Abstract

The Mekong Delta, early in the twenty-first century, is at a tipping point for sustainability. The delta is threatened by the implications of (1) damming and land-use changes in the drainage basin, (2) a burgeoning delta population in a nation (Vietnam) undergoing rapid development, (3) accelerating rates of rising sea level, and (4) an uncertain future climate that may impact tropical cyclone frequency and monsoonal precipitation patterns in the basin. These threats are present in other great rivers that emerge from the Himalayas. Two primary threats are examined in light of recent joint Vietnam-US studies in the largest distributary (Song Hau) of the Mekong River, in the shore-fringing mangroves, and on the adjacent subaqueous delta. We consider the implications of declining sediment loads from the catchment (as well as modification of the annual hydrograph) and flooding and salinity intrusion associated with relative sea level rise (eustatic + subsidence). This 2014–2015 study shows the interconnectivity in fluvial sediment supply to these parts of the delta: declining sediment loads and rising sea levels will likely impact distributary channel morphology and will alter estuarine circulation and sediment-trapping efficiency, all of which have feedbacks on sediment provision to the mangrove forests and the shelf.

Citation

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.

References

Albers, T., and K. Schmitt. 2015. Dyke design, floodplain restoration and mangrove co-management as parts of an area coastal protection strategy for the mud coasts of the Mekong Delta, Vietnam. Wetlands Ecology Management 23:991–1,004, https://doi.org/10.1007/s11273-015-9441-3.

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.

Allison, M.A., B.T. Yuill, T. Tornqvist, F. Amelung, T. Dixon, G. Erkens, R. Stuurman, C. Jones, G. Milne, M. Steckler, and others. 2016. Global risks and research priorities for coastal subsidence. Eos 97, https://doi.org/10.1029/2016EO055013.

Anthony, E.J., G. Brunier, M. Besset, M. Goichot, P. Dussouillez, and V.L. Nguyen. 2015. Linking rapid erosion of the Mekong River delta to human activities. Science Reports 5:14745, https://doi.org/10.1038/srep14745.

Balica, S., Q. Dinh, I. Popescu, T.Q. Vo, and D.Q. Pham. 2013. Flood impact in the Mekong Delta, Vietnam. Journal of Maps 10:257–268, https://doi.org/​10.1080/17445647.2013.859636.

Besset, M., E.J. Anthony, G. Brunier, and P. Dussouillez. 2016. Shoreline change of the Mekong River delta along the southern part of the South China Sea coast using satellite image analysis (1973–2014). Geomorphologie-Relief Processus Environnement 22:137–146.

Bianchi, T.S. 2016. Deltas and Humans. Oxford University Press, New York, 171 pp.

Bianchi, T.S., and M.A. Allison. 2009. Large-river delta-front estuaries as natural “recorders” of global environmental change. Proceedings of the National Academy of Sciences of the United States of America 106:8,085–8,092, https://doi.org/​10.1073/pnas.0812878106.

Biedenharn, D.S., C.R. Thorne, and C.C. Watson. 2000. Recent morphological evolution of the Lower Mississippi River. Geomorphology 34:227–249, https://doi.org/10.1016/S0169-555X(00)00011-8.

Boateng, I. 2012. GIS assessment of coastal vulnerability to climate change and coastal adaption planning in Vietnam. Journal of Coastal Conservation 16:25–36, https://doi.org/10.1007/s11852-011-0165-0.

Bravard, J.P., M. Goichot, and S. Gaillot. 2013. Geography of sand and gravel mining in the Lower Mekong River. EchoGéo 26, https://doi.org/10.4000/echogeo.13659.

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 destabilisation. Geomorphology 224:177–191, https://doi.org/10.1016/j.geomorph.2014.07.009.

Canestrelli, A., S. Fagherazzi, A. Defina, and S. Lanzoni. 2010. Tidal hydrodynamics and erosional power in the Fly River delta, Papua New Guinea. Journal of Geophysical Research 115:1–14, https://doi.org/10.1029/2009JF001355.

Chernetsky, A.S., H.M. Schuttelaars, and S.A. Talke. 2010. The effect of tidal asymmetry and temporal settling lag on sediment trapping in tidal estuaries. Ocean Dynamics 60:1,219–1,241, https://doi.org/10.1007/s10236-010-0329-8.

Church, J.A., P.U. Clark, A. Cazenave, J.M. Gregory, S. Jevrejeva, A. Levermann, M.A. Merrifield, G.A. Milne, R.S. Nerem, P.D. Nunn, and others. 2013. Sea level change. Pp. 1,137–1,216 in Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. T.F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex, and P.M. Midgley, eds, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

CIESIN (Center for International Earth Science Information Network, Columbia University). 2016. Documentation for the Gridded Population of the World, Version 4 (GPWv4). NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY, https://doi.org/10.7927/H4D50JX4.

Coleman, J.M., O.K. Huh, and D. Braud. 2008. Wetland loss in world deltas. Journal of Coastal Research 24:1–14, https://doi.org/10.2112/05-0607.1.

Darby, S.E., C.R. Hackney, 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.

Day, J.W., J. Agboola, Z. Chen, C. D’Elia, D.L. Forbes, L. Giosan, P. Kemp, C. Kuenzer, R.R. Lane, R. Ramachandran, and others. 2016. Approaches to defining deltaic sustainability in the 21st century. Estuarine, Coastal and Shelf Science 183:275–291, https://doi.org/10.1016/j.ecss.2016.06.018.

DeMaster, D.J., J.P. Liu, E. Eidam, C.A. Nittrouer, and T.T. Nguyen. In press. Determining rates of sediment accumulation on the Mekong shelf: Timescales, steady-state assumptions, and radiochemical tracers. Continental Shelf Research, https://doi.org/10.1016/j.csr.2017.06.011.

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.

Ellis, E.C., K.K. Goldewijk, S. Siebert, D. Lightman, and N. Ramankutty. 2013a. Anthropogenic Biomes of the World, Version 2 (1700). NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY, https://doi.org/10.7927/H4SF2T3M.

Ellis, E.C., K.K. Goldewijk, S. Siebert, D. Lightman, and N. Ramankutty. 2013b. Anthropogenic Biomes of the World, Version 2 (1900). NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY, https://doi.org/10.7927/H4J1012K.

Ellis, E.C., K.K. Goldewijk, S. Siebert, D. Lightman, and N. Ramankutty. 2013c. Anthropogenic Biomes of the World, Version 2 (2000). NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY, https://doi.org/10.7927/H4D798B9.

Erban, L.E., S.M. Gorelick, and H.A. Zebker. 2014. Groundwater extraction, land subsidence, and sea-level rise in the Mekong Delta, Vietnam. Environmental Research Letters, https://doi.org/​10.1088/1748-9326/9/8/084010.

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.

FAO (Food and Agriculture Organization of the United Nations). 2015. FAO GEONETWORK. Global population density estimates, 2015 (FGGD). (Latest update: GeoLayer). http://ref.data.fao.org/map?entryId=​6d78b970-5883-11db-b1aa-​000d939bc5d8&tab=about.

Fricke, A.T., C.A. Nittrouer, A.S. Ogston, and H.P. Vo-Luong. In press. Asymmetric progradation of a coastal mangrove forest controlled by combined fluvial and marine influence, Cù Lao Dung, Vietnam. Continental Shelf Research, https://doi.org/​10.1016/j.csr.2017.07.012.

Geyer, R.W., and P. MacCready. 2014. The estuarine circulation. Annual Review of Fluid Mechanics 46:175–197, https://doi.org/10.1146/annurev-fluid-010313-141302.

GSOV (General Statistics of Vietnam). 2017. https://www.gso.gov.vn.

Gupta, A., and S.C. Liew. 2007. The Mekong from satellite imagery: A quick look at a large river. Geomorphology 85:259–274, https://doi.org/​10.1016/j.geomorph.2006.03.036.

Kirwan, M.L., and P. Megonigal. 2013. Tidal wetland stability in the face of human impacts and sea-level rise. Nature 504:53–60, https://doi.org/10.1038/nature12856.

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

Krauss, K.W., K.L. McKee, C.E. Lovelock, D.R. Cahoon, N. Saintilan, R. Reef, and L. Chen. 2014. How mangrove forests adjust to rising sea level. New Phytologist 202:19–34, https://doi.org/10.1111/nph.12605.

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

Kummu, M., and O. Varis. 2007. Sediment-related impacts due to upstream reservoir trapping, the Lower Mekong River. Geomorphology 85:275–293, https://doi.org/10.1016/j.geomorph.2006.03.024.

LACPRA (Louisiana Coastal Protection and Restoration Authority). 2012. Louisiana’s Comprehensive Master Plan for a Sustainable Coast. State of Louisiana, Baton Rouge, LA, 170 pp.

Lauri, H., H. De Moel, P.J. Ward, T.A. Räsänen, M. Keskinen, and M. Kummu. 2012. Future changes in Mekong River hydrology: Impact of climate change and reservoir operation on discharge. Hydrology Earth Systems Science 16:4,603–4,619, https://doi.org/10.5194/hess-16-4603-2012.

Liu, J.P., D.J. DeMaster, C.A. Nittrouer, E.F. Eidam, and T.T. Nguyen. In press. A seismic study of the Mekong subaqueous delta: Proximal versus distal accumulation. Continental Shelf Research, https://doi.org/10.1016/j.csr.2017.07.009.

Lovelock, C.E., D.R. Cahoon, D.A. Friess, G.R. Guntenspergen, K.W. Krauss, R. Reef, K. Rogers, M.L. Saunders, F. Sidik, A. Swales, and others. 2015. The vulnerability of Indo-Pacific mangrove forests to sea-level rise. Nature 526:559–563, https://doi.org/10.1038/nature15538.

Lu, X.X., and R.Y. Siew. 2006. Water discharge and sediment flux changes in the Lower Mekong River. Hydrology Earth Systems Science 10:181–195, https://doi.org/10.5194/hess-10-181-2006.

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.

Meade, R.H. 1996. River-sediment input to major deltas. Pp. 63–85 in Sea-level Rise and Coastal Subsidence: Causes, Consequences, and Strategies. J.D. Milliman and B.U. Haq, eds., Kluwer Academic Publishers.

Meade, R.H., and J.A. Moody. 2010. Causes for the decline in suspended-sediment discharge in the Mississippi River system, 1940–2007. Hydrological Processes 24:35–49, https://doi.org/10.1002/hyp.7477.

Meybeck, M., and C.J. Vörösmarty. 2005. Fluvial filtering of land to ocean fluxes: From natural Holocene to Anthropocene. Comptes Rendus 337:107–123, https://doi.org/10.1016/j.crte.2004.09.016.

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

Milliman, J.D., and J.P. Syvitski. 1992. Geomorphic/​tectonic control of sediment discharge to the ocean: The importance of small mountainous rivers. Journal of Geology 100:525–544, https://doi.org/​10.1086/629606.

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.

Nardin, W., S. Locatelli, V. Pasquarella, M.C. Rulli, C.E. Woodcock, and S. Fagherazzi. 2016. Dynamics of a fringe mangrove forest detected by Landsat images in the Mekong River delta, Vietnam. Earth Surface Processes and Landforms 41:2,024–2,037, https://doi.org/10.1002/esp.3968.

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

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.

Nguyen, T.T.X., and C.D. Woodroffe. 2016. Assessing relative vulnerability to sea-level rise in the western part of the Mekong River Delta in Vietnam. Sustainability Science 11:645–659, https://doi.org/​10.1007/s11625-015-0336-2.

Phan, L.K., S.M. Jaap, V.T. de Vries, and M.J.F. Sive. 2015. Coastal mangrove squeeze in the Mekong Delta. Journal of Coastal Research 31:233–243, https://doi.org/10.2112/JCOASTRES-D-14-00049.1.

Qiu, C., and J. Zhu. 2013. Assessing the influence of sea level rise on salt transport processes and estuarine circulation in the Changjiang River estuary. Journal of Coastal Research 31:661–670, https://doi.org/10.2112/JCOASTRES-D-13-00138.1.

Ramirez, M.T., and M.A. Allison. 2013. Suspension of bed-material sand over lateral bars in the lower Mississippi River, southeastern Louisiana. Journal of Geophysical Research 118:1–20, https://doi.org/​10.1002/jgrf.20075.

Redmond, G., K.I. Hodges, C. Mcsweeney, R. Jones, and D. Hein. 2015. Projected changes in tropical cyclones over Vietnam and the South China Sea using a 25 km regional climate model perturbed physics ensemble. Climate Dynamics 45:1,983–2,000, https://doi.org/10.1007/s00382-014-2450-8.

Seto, K., B. Güneralp, and L.R. Hutyra. 2015. Global Grid of Probabilities of Urban Expansion to 2030. NASA Socioeconomic Data and Applications Center (SEDAC), Palisades, NY, https://doi.org/​10.7927/H4Z899CG.

Shearman, P., J. Bryan, and J.P. Walsh. 2013. Trends in deltaic change over three decades in the Asia-Pacific region. Journal of Coastal Research 29:1,169–1,183, https://doi.org/10.2112/JCOASTRES-D-12-00120.1.

Smajgl, A., T.Q. Toan, D.K. Nhan, J. Ward, N.H. Trung, L.Q. Tri, V.P.D. Tri, and P.T. Vu. 2015. Responding to rising sea levels in the Mekong Delta. Nature Climate Change 5:167–174, https://doi.org/10.1038/nclimate2469.

Stanley, D.J., and A.G. Warne. 1993. Nile Delta: Recent geological evolution and human impact. Science 5108:628–634, https://doi.org/10.1126/science.260.5108.628.

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

Swales, A., S.L. Bentley, and C.E. Lovelock. 2015. Mangrove-forest evolution in a sediment-rich estuarine system: Opportunists or agents of geomorphic change? Earth Surface Processes and Landforms 40:1,672–1,687, https://doi.org/10.1002/esp.3759.

Syvitski, J.P.M., A.J. Kettner, I. Overeem, E.H.W. Hutton, M.T. Hannon, G.R. Brakenridge, J. Day, C. Vorosmarty, Y. Saito, L. Giosan, and R.J. Nicholls. 2009. Sinking deltas due to human activities. Nature Geoscience 2:681–686, https://doi.org/10.1038/ngeo629.

Syvitski, J.P.M., C.J. Vörösmarty, A.J. Kettner, and P. Green. 2005. Impact of humans on the flux of terrestrial sediment to the global coastal ocean. Science 308:376–380, https://doi.org/10.1126/science.1109454.

Takagi, H., T.V. Ty, N.D. Than, and M. Esteban. 2014. Ocean tides and the influence of sea-level rise on floods in urban areas of the Mekong Delta. Journal of Flood Risk Management 8:292–300, https://doi.org/10.1111/jfr3.12094.

UNDP (United Nations Development Program). 2015. Human Development Report 2015. United Nations, New York, 272 pp.

Vörösmarty, C.J., J. Day, A. de Sherbinin, and J. Syvitski. 2009. Battling to save the world’s river deltas. Bulletin of Atomic Scientists 65:31–43, https://doi.org/10.2968/065002005.

Vörösmarty, C.J., and D. Sahagian. 2000. Anthropogenic disturbance of the terrestrial water cycle. BioScience 50:753–765, https://doi.org/​10.1641/​0006-3568​(2000)050​[0753:ADOTTW]​2.0.CO;2.

Wang, J.J., X.X. Lu, and M. Kummu. 2011. Sediment load estimates and variations in the lower Mekong River. River Research and Applications 27:33–46, https://doi.org/10.1002/rra.1337.

Wassman, R., N.X. Hein, C.T. Hoanh, and T.P. Tuong. 2004. Sea level rise affecting the Vietnamese Mekong Delta: Water elevation in the flood season and implications for rice production. Climate Change 66:89–107, https://doi.org/10.1023/​B:CLIM.0000043144.69736.b7.

Winterwerp, J.C., W.G. Borst, and M.B. De Vries. 2005. Pilot study on the erosion and rehabilitation of a mangrove mud coast. Journal of Coastal Research 21:223–230.

WLE–Greater Mekong (Water, Land, and Ecosystems–Greater Mekong). 2016. Dams in the Mekong River Basin: Commissioned, Under Construction and Planned Dams in April 2016. Vientiane, CGIAR Research Program on Water, Land and Ecosystems–Greater Mekong. 1 page map sheet. https://wle-mekong.cgiar.org/wp-content/uploads/Mekong_A0_2016_Final.pdf.

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 Coast Shelf Science 43:565–582, https://doi.org/10.1006/ecss.1996.0088.

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.

Xue, Z., J.P. Liu, and Q. Ge. 2011. Changes in hydrology and sediment delivery of the Mekong River in the last 50 years: Connection to damming, monsoon, and ENSO. Earth Surface Processes and Landforms 36:296–308, https://doi.org/10.1002/esp.2036.