Long-term evolution in the location, propagation, and magnitude of the tidal shear front off the Yellow River Mouth

Wang, Nan; Li, Guangxue; Qiao, Lulu; Shi, Jianghong; Dong, Ping; Xu, Jishang; Ma, Yanyan

doi:10.1016/j.csr.2017.01.020

Cited by 27 publications

(20 citation statements)

References 25 publications

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“…Indeed, tidal modeling suggests that a tidal shear front (e.g., Wang et al, 2017) may be present in this region that shows a drastic change from weak and more isotropic tidal currents west of Bogale promontory to highly oriented strong currents in the Gulf of Mottama (Rizal et al, 2012). Such a shear front would explain both the unusual channel-drift couplet and the fact that the Ayeyawady was able to build its delta west of the gulf.…”

Section: Discussionmentioning

confidence: 99%

On the Holocene evolution of the Ayeyawady megadelta

et al. 2018

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Abstract. The Ayeyawady delta is the last Asian megadelta whose evolution has remained essentially unexplored so far. Unlike most other deltas across the world, the Ayeyawady has not yet been affected by dam construction, providing a unique view on largely natural deltaic processes benefiting from abundant sediment loads affected by tectonics and monsoon hydroclimate. To alleviate the information gap and provide a baseline for future work, here we provide a first model for the Holocene development of this megadelta based on drill core sediments collected in 2016 and 2017, dated with radiocarbon and optically stimulated luminescence, together with a reevaluation of published maps, charts and scientific literature. Altogether, these data indicate that Ayeyawady is a mud-dominated delta with tidal and wave influences. The sediment-rich Ayeyawady River built meander belt alluvial ridges with avulsive characters. A more advanced coast in the western half of the delta (i.e., the Pathein lobe) was probably favored by the more western location of the early course of the river. Radiogenic isotopic fingerprinting of the sediment suggests that the Pathein lobe coast does not receive significant sediment from neighboring rivers. However, the eastern region of the delta (i.e., Yangon lobe) is offset inland and extends east into the mudflats of the Sittaung estuary. Wave-built beach ridge construction during the late Holocene, similar to several other deltas across the Indian monsoon domain, suggests a common climatic control on monsoonal delta morphodynamics through variability in discharge, changes in wave climate or both. Correlation of the delta morphological and stratigraphic architecture information on land with the shelf bathymetry, as well as its tectonic, sedimentary and hydrodynamic characteristics, provides insight on the peculiar growth style of the Ayeyawady delta. The offset between the western Pathein lobe and the eastern deltaic coast appears to be driven by tectonic-hydrodynamic feedbacks as the extensionally lowered shelf block of the Gulf of Mottama amplifies tidal currents relative to the western part of the shelf. This situation probably activates a perennial shear front between the two regions that acts as a leaky energy fence. Just as importantly, the strong currents in the Gulf of Mottama act as an offshore-directed tidal pump that helps build the deep mid-shelf Mottama clinoform with mixed sediments from the Ayeyawady, Sittaung and Thanlwin rivers. The highly energetic tidal, wind and wave regime of the northern Andaman Sea thus exports most sediment offshore despite the large load of the Ayeyawady River.

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Section: Discussionmentioning

confidence: 99%

On the Holocene evolution of the Ayeyawady megadelta

et al. 2018

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“…The gradients of the V velocity components on both sides of the CSFs were mostly distinct. The ratio between the vector difference of the V velocity components on both sides of the extracted CSFs and their distance was defined as the CSF shear intensity ( Q ), in units of m s −1 km −1 (Wang et al, ). The expression is as follows:

Q = \frac{(||, V_{1} - V_{2})}{D}

where Q is the shear intensity of the CSF, V 1 and V 2 are the V velocity components of the two points on both sides of the extracted CSF, and D is the distance between the two points.…”

Section: Methodsmentioning

confidence: 99%

“…Intensities of the CSFs 2.3.1. Method of Extracting the CSFs Within the area near the CSFs, the current velocity was very low, with a minimum value close to zero, and the current directions on both sides of the CSFs were in opposition (Gao et al, 2016;Li et al, 2001;Wang et al, 2007Wang et al, , 2017. Simultaneously, the direction of the north-south (V) velocity components was roughly consistent with the orientation of coastline in the Zhe-Min coastal area.…”

Section: Defining the Locations And Shearmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Additionally, distinct mass exchanges occur at shear fronts, and such fronts tend to have large gradients in velocity, suspended sediment concentration, salinity, and temperature (Wang et al, 2007). Numerous studies have focused on shear fronts, especially in estuarine environments (Blain et al, 2015;Gao et al, 2016;Li et al, 2001;Qiao et al, 2008;Wang et al, 2007Wang et al, , 2017, where the generation of tidal shear fronts is affected by bathymetry and tides (Blain et al, 2015;Qiao et al, 2008). However, little research has focused on current shear fronts (CSFs) (Liu et al, The CSF along the Zhejiang-Fujian (Zhe-Min) coastal area forms between the cold, fresh waters that flow southwestward along the coast and the warm, saline offshore waters that flow northeastward via the Taiwan Strait (Belkin et al, 2009) during winter (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Variation in the Current Shear Front and Its Potential Effect on Sediment Transport Over the Inner Shelf of the East China Sea in Winter

Liu

Qiao

et al. 2018

JGR Oceans

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The current shear fronts (CSFs) in the East China Sea have been observed during winter in previous studies. In this research, we systematically study characteristics and variation mechanism of the CSFs and its potential effects on the transport of water and suspended sediment and on the inner shelf mud area (ISMA), using the methods of observation data analysis and numerical simulation. The spatial structures, shear intensities, and sea‐land locations of the CSFs are obviously affected by wind, temperature and salinity. The CSFs curve seaward due to the nonuniformity of topography, and the tide causes its periodic and sea‐land shift. The landward U component near the CSFs indicate little cross‐CSF transport (i.e., the barrier effect). The CSFs are important hydrodynamic factors that affect the formation of the ISMA. The periodic shift of the CSFs in the longitudinal direction and its variations in spatial structure are the main mechanisms affecting the spatial distribution and thickness of the ISMA. However, the barrier effect of the CSFs can be interrupted, and both the strong wind in the northeast direction and baroclinic conditions are beneficial for cross‐CSF transport. Furthermore, cross‐CSF transports occur in the upper layers under northwest wind condition, in areas with nonuniformity of topography and during the spring tide period. Three cross‐shelf channels are identified in areas where the CSFs curve seaward resulting from nonuniformity of topography.

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Numerical Study on Seasonal Transportation of the Suspended Sediments in the Modern Yellow River Mouth Effected by the Artificial Water and Sediment Regulation

Wang

Qiao

et al. 2019

J. Ocean Univ. China

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Long-term evolution in the location, propagation, and magnitude of the tidal shear front off the Yellow River Mouth

Cited by 27 publications

References 25 publications

On the Holocene evolution of the Ayeyawady megadelta

On the Holocene evolution of the Ayeyawady megadelta

Variation in the Current Shear Front and Its Potential Effect on Sediment Transport Over the Inner Shelf of the East China Sea in Winter

Numerical Study on Seasonal Transportation of the Suspended Sediments in the Modern Yellow River Mouth Effected by the Artificial Water and Sediment Regulation

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