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Yao, J. and Tao, J., 2018. An Investigation of the Mixing and Exchange Characteristics in Tidal Channels of Radial Sand Ridges in the South Yellow Sea, China. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 136–140. Coconut Creek (Florida), ISSN 0749-0208. A three-dimensional hydrodynamic model coupled with a Lagrangian particle tracking model was applied in the radial sand ridges (RSR) area of the South Yellow Sea to investigate the flow and mass exchange characteristics between different channels. The Xiyang (XY), Chenjiawucao (CJWC), Kushuiyang (KSY) and Huangshayang (HSY) channels were chosen to represent the channels in all directions. The results showed that during the neap tides at both the surface and bottom locations, the particles were limited in their respective channels characterized by similar reciprocating trajectories. During the spring tides, the particles moved along reciprocating straight lines or in a clockwise spiral. The vertical circulation and water exchange in the tidal channels were significant, coinciding with the movement patterns of the particles. The hydrodynamic characteristics of the RSR are responsible for the significant differences of the transport characteristics in different channels. The XY Channel is controlled by the reciprocating flow, while others are dominated by varying degrees of rotary flow. The special geomorphology also plays an important role. The outcomes of this study may provide theoretical support for environmental management regarding the RSR area.

The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

Sinuous channel networks dissecting tidal wetlands are highly dynamic and are often abandoned as a result of channel captures and meander cutoffs. However, the effects of channel dynamics on blue carbon fluxes remain unclear. Analyses of abandoned tidal channels in the Venice Lagoon (Italy) demonstrate that they take up organic carbon at significantly faster rates than neighboring marshes. This is because, despite slightly lower sediment carbon density, abandoned tidal channels yield significantly higher rates of sediment vertical accretion owing to topographic accommodation and reduced flow velocities, which facilitate the deposition of particulate matter and debris. We estimate that abandoned tidal channels in Venice capture 17 tons of carbon annually, equivalent to 21 ha of marshes, despite covering only 3.5 ha in total. Hence we argue that abandoned tidal channels serve as hotspots for blue‐carbon accumulation and should be considered to improve estimates of carbon fluxes in coastal wetlands.

Khonde, N.; Katange, K.; Singh, G.; Kumar, A.; Maurya, D.M.; Giosan, L., and Ghosh, T., 2024. Recent sedimentation across Kori Creek in the western Great Rann of Kachchh Basin: Insights from tidal network changes, sedimentological, clay mineralogical, and rare earth element studies. Journal of Coastal Research, 40(2), 289–302. Charlotte (North Carolina), ISSN 0749-0208. Kori Creek is one of the most important creeks along the coastline of the Kachchh basin and forms a connecting passage between the Arabian Sea and the Great Rann of Kachchh (GRK) basin. Historically, this region has supported maritime activities between the Kachchh region and Sindh (now part of Pakistan) and witnessed significant landscape changes in the past few centuries. This study demonstrates tidal network changes that occurred over the past four decades (from 1984 to 2020) using satellite data in the Kori Creek region and western GRK basin. The results show that Kori Creek extended more than 30 km landward during the past four decades on account of ongoing tectonic adjustment and headward erosion of tidal channels in the GRK. Short sediment cores collected across the Kori creek in a transect provided evidence of the establishment, extension of tidal channels, and changing dominance of tidal flooding and channel influences on the sediment distribution. The clay mineralogical composition of the Kori Creek region shows the dominance of illite and chlorite over smectite and kaolinite minerals in general. However, from north to south (KC-1 to KC-5), clay compositions show a relative increase in smectite, indicating an increasing contribution due to sediment redistribution from the Indus delta, probably through coastal currents in modern time. The Rare Earth Element composition of the Kori Creek sediments is consistent and shows homogenised sediments that were dominantly sourced from the felsic rocks in the hinterland. Presently, the Kori Creek sediments do not receive significant sediments from rivers in the terrestrial part, the mineralogical composition, and chemical signatures suggest the Indus and the GRK as secondary sources for the Kori Creek modern sediments.

A barred tidal flat has grown in the north of Subarnarekha river estuarine system along the western coast of Bay of Bengal, Talsari, Odisha, over the last twenty years, from 2002 to 2022. The channels form an integral part of the tidal flat and act as conduits for supplying and draining sediments with flood and ebb flows. Multiple drainage basins with quantifiably different channel patterns are identified within the Talsari tidal flat. Two major types of tidal channels, namely through-flowing and dead-end channels, are recognized in the Talsari Tidal flat. Channel morphometric analysis reveals that the sand:mud ratio in the tidal flat sediments, along with slope, tidal range, current strength, vegetation cover and climate, strongly controls the channel pattern evolution in drainage basins within the tidal flat. Channel migration and filling patterns develop distinctly different sedimentary bodies with respect to laterally adjacent flat areas. High-energy climatic storms played an important role in transporting silty-muddy sediments to the tidal flat and also brought changes in channel morphometry along with the development of regionally developed scours.

Since the 1960s, ~5000 km2 of tidal deltaplain in southwest Bangladesh has been embanked and converted to densely inhabited, agricultural islands (i.e., polders). This landscape is juxtaposed to the adjacent Sundarbans, a pristine mangrove forest, both well connected by a dense network of tidal channels that effectively convey water and sediment throughout the region. The extensive embanking in poldered areas, however, has greatly reduced the tidal prism (i.e., volume of water) transported through local channels. We reveal that >600 km of these major waterways have infilled in recent decades, converting to land through enhanced sedimentation and the direct blocking of waterways by embankments and sluice gates. Nearly all of the observed closures (~98%) have occurred along the embanked polder systems, with no comparable changes occurring in channels of the Sundarbans (<2% change). We attribute most of the channel infilling to the local reduction of tidal prism in poldered areas and the associated decline in current velocities. The infilled channels account for ~90 km2 of new land in the last 40–50 years, the rate of which, ~2 km2/yr, offsets the 4 km2/yr that is eroded at the coast, and is equivalent to ~20% of the new land produced naturally at the Ganges-Brahmaputra tidal rivermouth. Most of this new land, called ‘khas’ in Bengali, has been reclaimed for agriculture or aquaculture, contributing to the local economy. However, benefits are tempered by the loss of navigable waterways for commerce, transportation, and fishing, as well as the forced rerouting of tidal waters and sediments necessary to sustain this low-lying landscape against rising sea level. A more sustainable delta will require detailed knowledge of the consequences of these hydrodynamic changes to support more scientifically-grounded management of water, sediment, and tidal energy distribution.

An ecomorphodynamic model was developed to study how Avicennia marina mangroves influence channel network evolution in sandy tidal embayments. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. The presence of mangroves was found to enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The enhanced branching of channels is also the result of a vegetation-induced increase in erosion threshold. On the other hand, this reduction in bed erodibility, together with the soil expansion driven by organic matter production, reduces the landward expansion of channels. The ongoing accretion in mangrove forests ultimately drives a reduction in tidal prism and an overall retreat of the channel network. During sea-level rise, mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone, while hindering both the branching and headward erosion of the landward expanding channels. The modelling results presented here indicate the critical control exerted by ecogeomorphological interactions in driving landscape evolution.

Tidal flats are some of the most dynamic coastal environments in the world, where traditional coastal mapping and monitoring provide insufficient temporal resolution to reliably map channels and sand flats. Satellite-based Synthetic Aperture Radar (SAR) enables regular cloud-penetrating detection of water flowing through channels within the tidal flats, referred to as tidal channels. This paper presents a method for detecting a path through tidal channels, using satellite imagery, that supports our understanding and safe exploitation of this valuable coastal environment. This approach is the first proposed to identify navigable paths in all conditions, with SAR images susceptible to variation due to weather and tidal conditions. Tidal channels are known to vary in SAR presentation, and we find that tidal flat presentation is also influenced by conditions. The most influential factor is the wind, with high winds causing an inversion in how both tidal flats and tidal channels present in SAR images. The presented method for the automatic detection of tidal channels accounts for this variability by using previous channel paths as a reference to reliably correct imagery and detect the latest path. The final algorithm produces paths with minor errors in 17.6% of images; the error rate increases to 71.7%, with an almost tenfold increase in errors, when the SAR image and paths are not adjusted to account for conditions. This capability has been used to support the Nith Inshore Rescue in attending call-outs from their base in Glencaple, UK, while the insights from monitoring tidal channels for a year demonstrate how periods of high river flow preceded major changes in the channel path.

Canals have played a significant role in promoting the prosperity of the shipping industry worldwide. Meanwhile, canal construction can alter the hydro-morphodynamic processes in coastal tidal channels. The Fangchenggang Canal is an extension route of the Pinglu Canal, which connects southwestern regions to the Beibu Gulf in the South China Sea by cutting across approximately 20 km of intertidal and dry land of the Qisha peninsula. A two-dimensional numerical model based on MIKE21 has been established to investigate the variations of tidal current structures and sediment transport characteristics. The maximum flow velocity within the main channel increases up to 1.18 m/s in the marine section. A bidirectional flow pattern has been observed in the land excavation segment. Numerical simulations of the sedimentation processes demonstrated potential erosion in the land excavation section due to the increased bed shear stress. The present study shares useful insights into the response mechanism of hydro-morphodynamic processes under canal construction. The quantitative simulations would support the environmental assessment and route planning of canal projects.

For a better understanding of the strong heterogeneities of the Mishrif Formation in the H Oilfield of southeast Iraq, the characterization of the carbonate architectures has become one of the key research departments of carbonate rocks. This study aims to reveal the architecture and controlling factors of the carbonate tidal channels in the MB1-2B sub-layer of the Mishrif Formation in response to the delineation of the tidal channels that have hydrocarbon potential. Three architectural elements and three architectural boundaries of the tidal channels were identified by interpreting the cores, well-logging, seismic, and analytical data. The results show that: (1) the architecture characteristics of tidal channels are mainly migrating type in the downstream zone, the side of concave bank of the tidal channels is usually filled with relatively coarse-grained grainstone; (2) the architecture characteristics of tidal channels are mainly swinging type in the upstream zone, showing the high porosity and permeability; (3) the architecture characteristics of tidal channels are mainly vertical-accretion type in the mid-regions, indicating the instantaneous current reversals and high geographical position. This analysis demonstrates that the best reservoir quality within the tidal channels is located in the bend of the tidal channel near the inner lagoon and open sea, it provides the geological models for later exploration and development in the Mishrif Formation.