Modeling the tidal channel morphodynamics in a macro-tidal embayment, Hangzhou Bay, China

Xie, Dongfeng; Wang, Zheng Bing; Gao, Shu; Vriend, H.J. de

doi:10.1016/j.csr.2009.03.009

Cited by 124 publications

(57 citation statements)

References 30 publications

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“…The bay is quite shallow with an average depth of 8-10 m at low tide, with the exception of some deep erosional channels along the northern bank. The bay morphology can be roughly divided into two parts along the Jianshanwai transection (Figure 1(a)), with relatively smooth muddy beds in the east and undular sandy beds in the west, the later characterized by alternations of tidal sand ridges and troughs together with some silty shoals [13,34,35].…”

Section: Study Areamentioning

confidence: 99%

Sedimentation processes and sedimentary characteristics of tidal bores along the north bank of the Qiantang Estuary

et al. 2012

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A tidal bore is a unique Earth surface process, characterized by its highly destructive energy, predictable periodicities and magnitudes, and the production of characteristic sedimentary features. Tidal bores and associated rapid flood flows are highly turbulent flows of the upper-flow regime with a velocity over several meters per second. Reynolds (R e ) and Froude (F r ) numbers, respectively, are larger than 10 4 and 1.0, making them significantly different from regular tidal flows but analogous to turbidity currents. Until now, understanding of tidal-bore depositional processes and products has been limited because of the difficulty and hazards involved with gauging tidal bores directly. The Qiantang bore is known as the largest breaking bore in the world. Field surveys were carried out in May 2010, along the north bank of the Qiantang Estuary to observe the occurrence of peak bores, including regular observations of current, water level and turbidity at the main channel. Several short cores were sampled on the intertidal flats to study the characteristic sedimentary features of tidal bores. Hydrodynamic and sedimentological studies show that the processes of sediment resuspension, transport and deposition are controlled primarily by the tidal bores, and the subsequent abruptly accelerated and decelerated flood flows, which only account for one tenth of each semidiurnal tidal cycle in the estuary. Tidal-bore deposits are generally poorly sorted because of rapid sedimentation after highly mixed suspension by intense turbulence. This behavior is characteristic of the absence of tractive-current depositional components in a C-M diagram. It also goes along with well-developed massive bedding, graded bedding, basal erosion structures, convolute bedding and dewatering structures. Together, these sedimentary features can constitute fingerprinting of turbidites, widely distributed in the deep-water environment. However, a tidal bore is triggered by intensely deformed tidal waves propagating into a shallow-water environment, which returns to regular tidal flows rapidly after the passage of the bore head. The tidal-bore deposits are usually bounded by the intertidal-flat deposits with typical tidal beddings at the top and on both flanks. The difference between tidal-bore deposits (TBD) and tidal sandy/muddy deposits (TSD/TMD) is evident not only in sedimentary structures, but also in the grain-size composition. They can be clearly distinguished in grain-size bivariate plots, typically the plot of mean grain size vs. standard deviation (or sorting). Some trend variations generally exist in mean grain size with TBD>TSD>TMD, sorting with TMD>TBD>TSD (larger value indicating poorer sorting), and both skewness and kurtosis with TSD>TBD>TMD. These findings will undoubtedly shed new light on our understanding of tidal-bore sedimentology, ancient tidal-bore sedimentary facies and environments, and related oil-and-gas field prospecting.

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Section: Study Areamentioning

confidence: 99%

Sedimentation processes and sedimentary characteristics of tidal bores along the north bank of the Qiantang Estuary

et al. 2012

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“…The Bay is affected by river runoff and tide from the East China Sea. The Yangtze (Changjiang) River with an average water runoff of 925 × 10 9 m 3 yr −1 and sediment load of 480 × 10 9 kg yr −1 supplied the dominant amount of sediment to the Hangzhou Bay Wang et al, 2008), where it is re-deposited by southward coastal currents and tides (Jilan and Kangshan, 1989;Xi et al, 2009). The climate is subtropical monsoonal with annual average temperature and rainfall of 16.3 • C and 1418 mm, respectively.…”

Section: Study Sitesmentioning

confidence: 99%

Intra- versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence

Mueller-Niggemann

Bannert²,

Schloter

et al. 2012

Biogeosciences

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Abstract. In order to assess the intrinsic heterogeneity of paddy soils, a set of biogeochemical soil parameters was investigated in five field replicates of seven paddy fields (50, 100, 300, 500, 700, 1000, and 2000 yr of wetland rice cultivation), one flooded paddy nursery, one tidal wetland (TW), and one freshwater site (FW) from a coastal area at Hangzhou Bay, Zhejiang Province, China. All soils evolved from a marine tidal flat substrate due to land reclamation. The biogeochemical parameters based on their properties were differentiated into (i) a group behaving conservatively (TC, TOC, TN, TS, magnetic susceptibility, soil lightness and colour parameters, δ 13 C, δ 15 N, lipids and n-alkanes) and (ii) one encompassing more labile properties or fast cycling components (N mic , C mic , nitrate, ammonium, DON and DOC). The macroscale heterogeneity in paddy soils was assessed by evaluating intra-versus inter-site spatial variability of biogeochemical properties using statistical data analysis (descriptive, explorative and non-parametric). Results show that the intrinsic heterogeneity of paddy soil organic and minerogenic components per field is smaller than between study sites. The coefficient of variation (CV) values of conservative parameters varied in a low range (10 % to 20 %), decreasing from younger towards older paddy soils. This indicates a declining variability of soil biogeochemical properties in longer used cropping sites according to progress in soil evolution. A generally higher variation of CV values (>20-40 %) observed for labile parameters implies a need for substantially higher sampling frequency when investigating these as compared to more conservative parameters. Since the representativeness of the sampling strategy could be sufficiently demonstrated, an investigation of long-term carbon accumulation/sequestration trends in topsoils of the 2000 yr paddy chronosequence under wetland rice cultivation restricted was conducted. Observations cannot be extrapolated to global scale but with coastal paddy fields developed on marine tidal flat substrates after land reclamation in the Zhejiang Province represent a small fraction (<1 %) of the total rice cropping area. The evolutionary trend showed that the biogeochemical signatures characteristic for paddy soils were fully developed in less than 300 yr since onset of wetland rice cultivation. A six-fold increase of topsoil TOC suggests a substantial gain in CO 2 sequestration potential when marine tidal wetland substrate developed to 2000 yr old paddy soil.

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“…This The sinking rate of suspended sediments varies with particle size, shape and relative density. In the study area, the suspended sediments consist mainly of fine particulate material and very fine suspended sediments released by the Changjiang River and Qiantang River [25,[42][43][44][45][46]. Beginning with the reference settling velocity of 0.0002 m/s given by Ramakrishnan and Rajawat [8], a uniform particle sinking rate 0.0006 m/s for suspended sediments is arrived at after model calibration.…”

Section: Sediment Module Configurationmentioning

confidence: 99%

“…The silty clay results from the accumulation of Changjiang River sediments, while the silty, clay-like sands are mostly derived from the old Yellow River. Sediments in the Hangzhou Bay are predominantly composed of fine and medium silt, with an averaged grain size less than 0.038 mm and are vertically well-mixed [44][45][46]. Suspended sediments are advected and diffused throughout the water column by the currents from the hydrodynamic model.…”

Section: Sediment Module Configurationmentioning

confidence: 99%

Using GOCI Retrieval Data to Initialize and Validate a Sediment Transport Model for Monitoring Diurnal Variation of SSC in Hangzhou Bay, China

Yang

Mao

Huang

et al. 2016

Water

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Abstract:The diurnal variation of the suspended sediment concentration (SSC) in Hangzhou Bay, China has been investigated using remotely-sensed SSC derived from the Geostationary Ocean Color Imager (GOCI) in combination with a coupled hydrodynamic-ecological model for regional and shelf seas (COHERENS). The SSC maps were inferred through a UV-AC atmospheric correction algorithm and an empirical inversion algorithm from the GOCI Level-1B data. The sediment transport model was initialized from maps of the GOCI-derived SSC and the model results were validated through a comparison with remotely-sensed data. The comparison demonstrated that the model results agreed well with the observations. The relationship between SSC distribution and hydrodynamic conditions was analyzed to investigate the sediment transport dynamics. The model's results indicate that the action of tidal currents dominate the sediment deposition and re-suspension in the coastal waters of the East China Sea. This is especially the case in Hangzhou Bay where the tidal currents are strongest. The satellite-derived sediment data product can not only dramatically improve the specification of the initial conditions for the sediment model, but can also provide valuable information for the model validation, thereby improving the model's overall performance.

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Modeling the tidal channel morphodynamics in a macro-tidal embayment, Hangzhou Bay, China

Cited by 124 publications

References 30 publications

Sedimentation processes and sedimentary characteristics of tidal bores along the north bank of the Qiantang Estuary

Sedimentation processes and sedimentary characteristics of tidal bores along the north bank of the Qiantang Estuary

Intra- versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence

Using GOCI Retrieval Data to Initialize and Validate a Sediment Transport Model for Monitoring Diurnal Variation of SSC in Hangzhou Bay, China

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