Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam.

Unverricht, D., Szczucinski, W., Stattegger, Karl, Jagodzinski, R., Le, X. T. and Kwong, L. L. W. (2013) Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam. Global and Planetary Change, 110 . pp. 223-235.

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Abstract

The Mekong River Delta is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoon-driven river discharge and human impact (agriculture, fishing, sand dredging, tourism). The present study aims to document the seafloor relief, sediment distribution and sediment accumulation rates to interpret modern sediment transport directions and main sedimentation processes in the subaqueous Mekong Delta. The major results of this investigation include the detection of two delta fronts 200 km apart, one at the mouth of the Bassac River (the biggest branch of the Mekong Delta) and the other around Cape Ca Mau (most south-western end of the Mekong Delta). Additionally, a large channel system runs in the subaqueous delta platform parallel to the shore and between the two fronts. The sediment accumulation rates vary greatly according to the location in the subaqueous delta and have reached up to 10 cm/yr for the last century. A cluster analysis of surface sediment samples revealed two different sediment types within the delta including a well-sorted sandy sediment and a poorly sorted, silty sediment. In addition, a third end member with medium to coarse sand characterised the distant parts of the delta at the transition to the open shelf. The increase of organic matter and carbonate content to the bottom set area and other sedimentary features such as shell fragments, foraminiferas and concretions of palaeo-soils that do not occur in delta sediments, supported grain size-based classification. Beginning in front of the Bassac River mouth, sedimentary pattern indicates clockwise sediment transport alongshore in the western direction to a broad topset area and the delta front around Cape Ca Mau. Our results clearly show the large lateral variability of the subaqueous Mekong Delta that is further complicated by strong monsoon-driven seasonality. River, tidal and wave forcing vary at local and seasonal scales with sedimentary response to localised short-term depositional patterns that are often not preserved in long-term geological records.

Document Type: Article
Additional Information: Times Cited: 2 Unverricht, Daniel Szczucinski, Witold Stattegger, Karl Jagodzinski, Robert Xuan Thuyen Le Kwong, Laval Liong Wee Si B
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R06
Kiel University
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
ISSN: 0921-8181
Projects: Future Ocean
Date Deposited: 08 Jul 2014 09:56
Last Modified: 14 Apr 2017 11:15
URI: http://oceanrep.geomar.de/id/eprint/25234

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