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Tidal channels migrate frequently under the combined actions of coastal dynamics and bank collapse, significantly affecting the stability of tidal network systems. However, existing studies mainly focus on in-channel flow erosion during flood tides, while less efforts are devoted to bank retreat driven by seepage erosion during the ebb tides. It is thus urgent to understand the underlying mechanism of bank collapse that driven by seepage. This study investigates the impact of seepage head height on bank collapse through physical experiments, including bank collapse modes, bank line variations and bank retreat rate. Results show that the process of bank collapse is related to seepage head height. We observe a transition of bank collapse mode from cantilever failure to tension failure, with increased seepage head height. A positive correlation between bank retreat rate and seepage head height is found. Overall, this research reveals the mechanism of bank collapse driven by seepage, and explains the distinct failure process of bank collapse over ebb tides, which is of great significance to the study of tidal channel evolution. [ABSTRACT FROM AUTHOR]

A series of benchmarks were setup on the south Chuandong tidal flat (Yancheng, Jiangsu). Monthly observation of the surface elevation has been performed for 7 years (October 2012 to November 2018) using the Rod Surface Elevation Table(RSET). The edge of the Spartina alterniflora was obtained from the remote sensing images. The long-term evolution of the mudflat and the influence of growth of Spartina alterniflora were evaluated. Results show that: the subsurface processes (e.g., soil expansion and compression) is the key factor affecting the evolution of mudflat at the highest position of the tidal flat. The growth of salt marsh increases the amount of sediment deposition. With the propagation of the edge of salt marsh, the annual sediment deposition at the central salt marsh decreases gradually. In the vicinity of the frontier of the salt marsh, the annual siltation volume increases. Even though, the bare flat evolution trend is hardly affected by the advancing of salt marsh. From the landside to seaside, the cross-shore profile can be divided into 4 zones, which are erosion-deposition balance, rapid deposition, erosion-deposition balance and rapid erosion zones, respectively. The slope of the intertidal flat increases evidently. The tidal flat resources decrease constantly in the past 7 years. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Water Science / Shuikexue Jinzhan is the property of Editorial Board of Advances in Water Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Advances in Water Science / Shuikexue Jinzhan is the property of Editorial Board of Advances in Water Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To explore the influence of sea level rise on the evolution of tidal flat and tidal creek system, adistorted physical model was established, taking a silt-muddy tidal flat-creek system in the central Jiangsu coastas the prototype. Based on the model, a variety of parameters were analyzed to illustrate the properties of the creek system changed with the sea level rise, such as duration of submergence, drainage density, cross section profile of the tidal channel, etc. Results indicate that the elongation increases more rapid than the elaboration at the initial stage of the creek system development, but both approach a dynamic equilibrium ultimately. Under the pressure of sea level rise, the inundation period increases hence the exposure duration of the tidal flats decreases, resulting in reduced shaping effects of the shift return flow on the creek bottom. Both mean unchannelled length and Hortonian drainage length show a decreasing trend, indicating a higher drainage ability of the creek system. In addition, the width/depth ratio follows an approximate lognormal distribution. The cross-section area and the width/depth ratio increase with sea level rise, as well as the distribution range of the width/depth ratio. [ABSTRACT FROM AUTHOR]

To explore the initiation and development of tidal creek network driven by tidal currents, an experimental physical model was established based on the prototype of a silt-muddy tidal flat-creek system on the Jiangsu coast. The evolutional process was simulated with an initially gentle bed slope of about 1%. The movement of flow and sediment, as well as the influence of tidal range on tidal creek development, was analyzed. The results indicated that tidal creek development was influenced by the bed slope variation. For the cases of uniform bed slope, the connection of neighboring tidal creeks, rather than headward erosion as shown by previous studies, resulted in the development of tidal networks. A strong flow and sediment movement occurred at the early flood and the late ebb stages, and sediment movement was most active in the mid-intertidal flat. Tidal range had little influence on the overall pattern formation and the structure of tidal networks. The relationship between the mean drainage path length and the sub-basin area generally followed a power-law function. Tidal networks approached a dynamic equilibrium state earlier under larger tidal ranges which contributed more to the development of the tidal creek widths. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Water Science / Shuikexue Jinzhan is the property of Editorial Board of Advances in Water Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Taking a channel downstream the Sheyang sluice as a prototype, a two-dimensional generalized morphodynamic model is established to investigate the siltation mechanism of a typical channel downstream floodgate in muddy coasts, China. The influence of runoff on hydro-sediment dynamics, as well as the souring and silting evolution in the channel, has been explored with and without considering the change of annual runoff distribution, respectively. A semi-empirical equation describing the relation between the equilibrium discharge and the ratio of runoff volume in flood season, channel averaged cross-section, offshore tidal range, tidal wave deformation, channel length and other related factors is established. For a particular channel which is practically in dynamic equilibrium state of erosion-siltation, the above-mentioned equation can be simplified as a simple form of expression of equilibrium discharge and channel averaged cross-section. And the simplified form of this formula is validated by observational data. [ABSTRACT FROM AUTHOR]