TY - JOUR
T1 - Sediment distribution along the fluvial to marine transition zone of the Dong Nai River System, southern Vietnam
AU - Gugliotta, Marcello
AU - Saito, Yoshiki
AU - Ta, Thi Kim Oanh
AU - Nguyen, Van Lap
AU - Uehara, Katsuto
AU - Tamura, Toru
AU - Nakashima, Rei
AU - Lieu, Kim Phuong
N1 - Funding Information:
This research was funded by a KAKENHI grant from the Japan Society for the Promotion of Science (JSPS) (Grant Number JP 17H02980 ) and a MOST grant from Vietnam (Grant Number KC.09.35/16-20 ). Gugliotta benefited of a Standard Postdoctoral Fellowship for Overseas Researchers from the JSPS (Grant Number JP 17F17330 ). The authors would like to thank the Editor-in-Chief, Edward Anthony, and three anonyms reviewers for providing valuable comments that helped to significantly improve this manuscript.
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/11
Y1 - 2020/11
N2 - Studies on the sediment distribution along the fluvial to marine transition zone are rare and have focused on large-scale systems. Here, we report a case study from the Dong Nai River System (DNRS), a small-scale, tide-dominated river delta from southern Vietnam. The study is based on 80 channel bed sediment samples, together with channel depth, temperature, and salinity measurements, identification of mangroves and mollusks, and grain-size analysis. Year-round meter-scale water-level fluctuations due to tides are present across the entire study area, whereas saline-water intrusion affects the entire studied part of the Vam Co Dong–Vam Co River and the majority of the studied part of the Dong Nai–Soai Rap River. The sediment distribution of both channels highlights the presence of a downstream area characterized by soft mud indicating active deposition, and upstream areas characterized by sand and gravel sediments with abundant bedrock clasts and other evidence of the extremely limited sedimentation (e.g., encrusting biostructures, borings, coating, and agglutinated mats). The coarser-grained sand and gravel are likely reworked from local bedrock and transported for short distances as also suggested by their angularity and the similarities with Pleistocene sedimentary and igneous rocks in the study area. The sediment of the DNRS is overall coarser and muddier than the sediment of the Mekong, likely reflecting the smaller scale of this system, the lower discharge, and the local sediment supply from the bedrock.
AB - Studies on the sediment distribution along the fluvial to marine transition zone are rare and have focused on large-scale systems. Here, we report a case study from the Dong Nai River System (DNRS), a small-scale, tide-dominated river delta from southern Vietnam. The study is based on 80 channel bed sediment samples, together with channel depth, temperature, and salinity measurements, identification of mangroves and mollusks, and grain-size analysis. Year-round meter-scale water-level fluctuations due to tides are present across the entire study area, whereas saline-water intrusion affects the entire studied part of the Vam Co Dong–Vam Co River and the majority of the studied part of the Dong Nai–Soai Rap River. The sediment distribution of both channels highlights the presence of a downstream area characterized by soft mud indicating active deposition, and upstream areas characterized by sand and gravel sediments with abundant bedrock clasts and other evidence of the extremely limited sedimentation (e.g., encrusting biostructures, borings, coating, and agglutinated mats). The coarser-grained sand and gravel are likely reworked from local bedrock and transported for short distances as also suggested by their angularity and the similarities with Pleistocene sedimentary and igneous rocks in the study area. The sediment of the DNRS is overall coarser and muddier than the sediment of the Mekong, likely reflecting the smaller scale of this system, the lower discharge, and the local sediment supply from the bedrock.
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U2 - 10.1016/j.margeo.2020.106314
DO - 10.1016/j.margeo.2020.106314
M3 - Article
AN - SCOPUS:85091231126
VL - 429
JO - Marine Geology
JF - Marine Geology
SN - 0025-3227
M1 - 106314
ER -