Where and why do creeks evolve on fringing and bare tidal flats?

Hanssen, J.L.J.; Prooijen, Bram C. van; Volp, N.D.; Vet, P.L.M. de; Herman, Peter M. J.

doi:10.1016/j.geomorph.2022.108182

Cited by 8 publications

(4 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In agreement with the observation of various natural systems worldwide, our model results demonstrate that parallel tidal channels can be formed by a combination of alongshore tidal forcing and alongshore uniformity in bed topography (e.g., similar bed profile shape and local topographic relief magnitude in the alongshore direction). The creeks present on fringing tidal flats originate at the transition zone between the milder-slope upper and steeper-slope lower flats where the highest ebb velocities and largest velocity gradients tend to occur 29 . The parent channel provides a conduit for the alongshore flow constrained within the banks, and the lateral gradient of bed elevation controls the bend of the flow direction.…”

Section: Discussionmentioning

confidence: 99%

Cross-shore parallel tidal channel systems formed by alongshore currents

Zhou,

Wei,

Geng

et al. 2024

Nat Commun

View full text Add to dashboard Cite

Parallel tidal channel systems, characterized by commonly cross-shore orientation and regular spacing, represent a distinct class of tidal channel networks in coastal environments worldwide. Intriguingly, these cross-shore oriented channel systems can develop in environments dominated by alongshore tidal currents, for which the mechanisms remain elusive. Here, we combine remote sensing imagery analysis and morphodynamic simulations to demonstrate that the deflection of alongshore tidal currents at transitions in bed elevation determines the characteristic orientation of the parallel tidal channels. Numerical results reveal that sharp changes in bed elevation lead to nearly 90-degree intersection angles, while smoother transitions in bed profiles result in less perpendicular channel alignments. These findings shed light on the potential manipulation of tidal channel patterns in coastal wetlands, thus equipping coastal managers with a broader range of strategies for the sustainable management of these vital ecosystems in the face of climate change and sea level rise.

show abstract

Section: Discussionmentioning

confidence: 99%

Cross-shore parallel tidal channel systems formed by alongshore currents

Zhou,

Wei,

Geng

et al. 2024

Nat Commun

View full text Add to dashboard Cite

show abstract

“…The profile shape is linear, convex-up or concave-up. The convex-up and concave-up profiles consist of three parts with a varying tidal flat slope: the upper part of the tidal flat with slope S up , a curved transition zone and the lower tidal flat with the slope S low (Hanssen et al, 2022). Figure 1C is an example of a convex-up tidal flat with a mild upper slope (0-600 m), the transition zone (600-650 m) and the steep lower slope (650-750 m).…”

Section: Profile Extraction and Characterizationmentioning

confidence: 99%

“…With bed level (z b [m]) as function of the horizontal position (x [m]), length of the lower flat (L [m]), the slope of the lower and upper flat (S low [-] and S up [-], respectively), z 0 [m] is the height of the intersection point of the upper and lower slope when extrapolating both slopes, and the curvature of the transition (d ½m between the upper and the lower flat). The reader is referred to Hanssen et al (2022) for a detailed description of this method. This equation can be used for concave-up as well as for convex-up profiles.…”

Section: Profile Extraction and Characterizationmentioning

confidence: 99%

The shape of fringing tidal flats in engineered estuaries

Hanssen,

van Prooijen,

van Maren

2024

Front. Mar. Sci.

View full text Add to dashboard Cite

For the management of estuaries and the preservation of tidal flats it is crucial to understand the tidal flat shape and development. Previous work focused predominantly on the quasi-equilibrium shape of tidal flats along open coasts with a dominant cross-shore flow and wave exposure. This paper evaluates the shape of fringing tidal flats in engineered estuaries, where longshore velocities generally dominate. Using a long-term (20 years) topographic data set of an anthropogenically modified estuary in the Netherlands (the Western Scheldt estuary), we relate key profile shape parameters and changes over time to natural and anthropogenic processes. In an engineered estuary, the tidal flat shape depends on the estuary geometry, hydrodynamic forcings and human interventions. In contrast to open coast tidal flats, the presence of the channel and dominant longshore flow determines the available cross-shore length (accommodation space) of the tidal flat and the shape of the tidal flat. This accommodation space defines the maximum tidal flat height and opportunity for marsh development. We propose the use of the Index of Development, indicating to what extend tidal flats have space to develop. This index is not only influenced by longshore and cross-shore flow, but also (or even more) by hydraulic structures, dike realignments and channel migration. Especially the latter two strongly influence the accommodation space and thereby the maximum tidal flat height and the opportunity for marsh development. For large stretches of the Western Scheldt, the accommodation space is too small, and the majority of the tidal flats do not vertically extent to mean high water. The success of tidal flat and marsh restoration projects depends on the accommodation space.

show abstract

“…Although s5 had the largest velocities than other two stations, tidal currents at Dafeng tidal flat were much smaller than that at Jianggang. One reason was that Dafeng tidal flat had a convex-up shape, which favored to tidal current energy dissipation on the lower tidal flat, therefore, velocities were usually highest in the middle tidal flat (Hanssen et al 2022). Jianggang profile was concave-up, and the comparatively large water depth along tidal flat profile favored energy transferring to the upper flat.…”

Section: Offshore Hydrodynamics and Tidal Flat Profilesmentioning

confidence: 99%

Hydrodynamics and sediment transport patterns on intertidal flats along middle Jiangsu coast

Xing

Wang

Jia

2022

Anthropocene Coasts

View full text Add to dashboard Cite

Two field campaigns in Dafeng and Jianggang were organized to compare spatial variations of hydrodynamic characteristics and sediment transport patterns on intertidal flats of different types with distinct human interferences along middle Jiangsu coast, China. The major contributors to the different patterns of sediment dynamics between the two tidal flats were offshore tidal current field and human interference. Offshore tidal force provide the basic setup of tidal current patterns on tidal flats, which is then modified by local morphology. Seawalls parallel to coast reduce tidal flat width, forcing tidal energy to dissipate within a shorter distance and thus influencing tidal flat morphology. Seawalls vertical to coast and major tidal current significantly reduce tidal current speed, which favors sediment deposition on tidal flats. Two seawalls built on both sides of the observational tidal flat profile caused much reduced current speed at Dafeng tidal flat, comparing to the offshore station. Being exposed to offshore radial tidal currents, hydrodynamics at Jianggang was much stronger than that at Dafeng. Residual currents at both areas showed net landward transport at the lower flat and net seaward transport at the upper flat, in favor to sediment accumulation at the middle flat. Sediment flux over tidal cycles showed net landward sediment transport at Dafeng, and net seaward transport at Jianggang, consistent with the convex-up accretion-dominated profile observed at Dafenge, and concave-up erosion-dominated profile observed at Jianggang. The instantaneons sediment flux changed significantly due to variations in velocity and sediment concentrations, but these terms counteracted with each other within tidal cycles, leading to the dominant role of Eulerian flux in determining net sediment flux over tidal cycles.

show abstract

Where and why do creeks evolve on fringing and bare tidal flats?

Cited by 8 publications

References 35 publications

Cross-shore parallel tidal channel systems formed by alongshore currents

Cross-shore parallel tidal channel systems formed by alongshore currents

The shape of fringing tidal flats in engineered estuaries

Hydrodynamics and sediment transport patterns on intertidal flats along middle Jiangsu coast

Contact Info

Product

Resources

About