Role of wind in erosion‐accretion cycles on an estuarine mudflat

Shi, Benwei; Yang, S.L.; Wang, Ya Ping; Li, G. C.; Li, M. L.; Li, P.; Li, Chunyan

doi:10.1002/2016jc011902

Cited by 32 publications

(20 citation statements)

References 76 publications

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“…Given that sediments on the Wanggang mudflat originate from the Yangtze River, the dry density used for this surface sediment (ρ dry ) was 1,300 kg/m 3 based on the recommendation of Yang et al (). M E is the erodibility parameter (m/Pa/s), and the applied value of M E in this study was 2.19 × 10 −6 m/Pa/s, which is applicable for the neighboring intertidal mudflat at the Yangtze delta front based on Shi et al (), and is also of the same order of magnitude as a large number of published results (e.g., Shi et al, ; Winterwerp & van Kesteren, ). τ ce is the critical shear stress for the erosion of bottom sediments (N/m 2 ).…”

Section: Methodsmentioning

confidence: 51%

“…There are many uncertainties in measurements of bed‐level changes in a highly turbid estuarine environment (e.g., Miao, 2016; Shi et al, ). The first reason for this is the universal presence of a fluid‐like mud layer due to the effect of high SSCs on intertidal flats (e.g., Andersen et al, ; Yang et al, , 2005; Shi et al, ). This is supported by observations on another mudflat in the Yangtze delta front, where >10 kg/m 3 of near‐bed SSC can be generally observed, even during normal weather (Miao, ; Figure ).…”

Section: Discussionmentioning

confidence: 99%

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Erosion and Accretion on a Mudflat: The Importance of Very Shallow‐Water Effects

et al. 2017

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Understanding erosion and accretion dynamics during an entire tidal cycle is important for assessing their impacts on the habitats of biological communities and the long‐term morphological evolution of intertidal mudflats. However, previous studies often omitted erosion and accretion during very shallow‐water stages (VSWS, water depths < 0.20 m). It is during these VSWS that bottom friction becomes relatively strong and thus erosion and accretion dynamics are likely to differ from those during deeper flows. In this study, we examine the contribution of very shallow‐water effects to erosion and accretion of the entire tidal cycle, based on measured and modeled time‐series of bed‐level changes. Our field experiments revealed that the VSWS accounted for only 11% of the duration of the entire tidal cycle, but erosion and accretion during these stages accounted for 35% of the bed‐level changes of the entire tidal cycle. Predicted cumulative bed‐level changes agree much better with measured results when the entire tidal cycle is modeled than when only the conditions at water depths of >0.2 m (i.e., probe submerged) are considered. These findings suggest that the magnitude of bed‐level changes during VSWS should not be neglected when modeling morphodynamic processes. Our results are useful in understanding the mechanisms of micro‐topography formation and destruction that often occur at VSWS, and also improve our understanding and modeling ability of coastal morphological changes.

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Section: Methodsmentioning

confidence: 51%

Section: Discussionmentioning

confidence: 99%

Erosion and Accretion on a Mudflat: The Importance of Very Shallow‐Water Effects

et al. 2017

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“…Observational (Andersen et al, ; Christiansen et al, ; Deloffre et al, , ; Fan et al, ; Marion et al, ; Shi et al, ; Wang et al, ; Yang et al, , ) and modeling (Fagherazzi et al, ; Hu et al, ; Maan et al, ; Roberts et al, ) studies have both revealed that waves have important impacts on the morphology and sediment grain size of tidal flats. So future research should couple the effects of cross‐shore and alongshore tidal currents including waves.…”

Section: Discussionmentioning

confidence: 99%

“…Observational (Andersen et al, 2006;Christiansen et al, 2006;Deloffre et al, 2005Deloffre et al, , 2007Fan et al, 2006;Marion et al, 2009;Shi et al, 2017;Wang et al, 2009;Yang et al, 2003Yang et al, , 2008 Here we only considered one mud fraction and one sand fraction in the models. In fact, both sand and mud can be divided into more fractions of different properties.…”

Section: Future Workmentioning

confidence: 99%

Sand‐Mud Tidal Flat Morphodynamics Influenced by Alongshore Tidal Currents

Wang

et al. 2019

JGR Oceans

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Tidal flats, where significant land‐ocean interactions take place, are often abstracted as a cross‐shore bed profile with sediment zonation from the lower sand flat to the upper mud flat. However, in addition to cross‐shore tidal currents, the impact of the alongshore components on cross‐shore sediment transport, morphological evolution, and sediment grain‐size change remains unclear. Here we investigated sand‐mud tidal flat morphodynamics in the absence of waves by combining approaches of field observations, numerical modeling, and analytical interpretations, based on the example of the tidal flat on the central Jiangsu coast, China. The results show that the morphodynamic processes are complicated by the interactions of cross‐shore and alongshore tidal currents, cross‐shore flat morphology, and sediment zonation. With amplified phase lags of the alongshore tidal level at the boundaries, alongshore currents become dominant over cross‐shore tidal currents on the lower flat, while the upper flat is always dominated by the cross‐shore currents. Therefore, bed profiles and mud content on the upper flat were independent of the alongshore tidal current magnitude, being convex‐up and consisting of mud. In contrast, the strong alongshore currents can erode mud on the lower flat and promote landward sand transport from the subtidal area to the lower flat, forming a sand flat. The maximum tidal bed shear stress is almost spatially uniform across the muddy area but pronouncedly elevated where the bed sediment coarsens on the lower flat. The contributions of the alongshore tidal currents and sand‐mud sorting processes should be appropriately addressed in similar coastal environments.

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“…Many studies have focused on wind effects on morphodynamic processes on intertidal flats (Friedrichs 1995;Fagherazzi et al 2007;Fagherazzi and Wiberg 2009;Mariotti and Fagherazzi 2013;Hunt et al 2017;Shi et al 2017). These studies emphasize the importance of wind-wave effects on estuarine morphodynamics; mechanisms of wave-induced sedimentary processes are already well described (Green and Coco 2014).…”

Section: Introductionmentioning

confidence: 99%

Wind influence on the orientation of estuarine landforms: An example from Lake Illawarra in southeastern Australia

Deng

Jones

Rogers

et al. 2018

Earth Surf Processes Landf

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We propose a type of a quasi‐equilibrium, which describes a convergence of the estuarine system towards a form whose planimetric orientation is along the prevailing winds. By using the microtidal Lake Illawarra in southeastern Australia as an example, we describe sediment convergent and divergent processes that induce such an equilibrium controlled by the complex configuration of the shoreline relative to the prevailing winds. For a complex estuarine sedimentary system with a mixture of non‐cohesive and cohesive sediments, alongshore distribution of fluvial or marine sand deposition and associated subaqueous morphology reflects alongshore redistribution of sediments from rivers and the tidal inlet. The orientation of the second‐order polynomial trend surface of estuarine morphology is consistent with prevailing wind directions. Along the lake shore, there are extensive narrow flats mainly covered by fluvial or marine sands shaped by the prevailing winds. The implementation of the Delft3D flow model coupled with the SWAN wave model driven by idealized prevailing winds indicates the potential of sediment convergent and divergent transport at the embayment and promontory shoreline, which appears to be similar to the alongshore distribution of sandy sediments and the nearshore flats. Alongshore transport of sandy sediments is primarily induced by the wave refraction on the shore, while the currents are more effective in transporting fine‐grained sediments such as mud or clay. Finally, we suggest a conceptual model that describes potential sediment transport of convergence and divergence on the embayment or promontory shoreline that is normal to the prevailing winds. Orientation of the estuary follows the convergence centre of sediment transport driven by the prevailing winds with the largest fetch. A quantitative threshold for such sediment redistribution may be determined in the future. © 2018 John Wiley & Sons, Ltd.

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Role of wind in erosion‐accretion cycles on an estuarine mudflat

Cited by 32 publications

References 76 publications

Erosion and Accretion on a Mudflat: The Importance of Very Shallow‐Water Effects

Erosion and Accretion on a Mudflat: The Importance of Very Shallow‐Water Effects

Sand‐Mud Tidal Flat Morphodynamics Influenced by Alongshore Tidal Currents

Wind influence on the orientation of estuarine landforms: An example from Lake Illawarra in southeastern Australia

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