The Impact of Wind on Flow and Sediment Transport over Intertidal Flats

Abstract

Sediment transport over intertidal flats is driven by a combination of waves, tides, and wind-driven flow. In this study we aimed at identifying and quantifying the interactions between these processes. A five week long dataset consisting of flow velocities, waves, water depths, suspended sediment concentrations, and bed level changes was collected at two locations across a tidal flat in the Wadden Sea (The Netherlands). A momentum balance was evaluated, based on field data, for windy and non-windy conditions. The results show that wind speed and direction have large impacts on the net flow, and that even moderate wind can reverse the tidal flow. A simple analytical tide–wind interaction model shows that the wind-induced reversal can be predicted as a function of tidal flow amplitude and wind forcing. Asymmetries in sediment transport are not only related to the tide–wind interaction, but also to the intratidal asymmetries in sediment concentration. These asymmetries are influenced by wind-induced circulation interacting with the large scale topography. An analysis of the shear stresses induced by waves and currents revealed the relative contributions of local processes (resuspension) and large-scale processes (advection) at different tidal flat elevations.

Characterizing the Composition of Sand and Mud Suspensions in Coastal and Estuarine Environments Using Combined Optical and Acoustic Measurements

“…[2020]; Colosimo et al [2020]; Pomeroy et al [2021]). Our approach thus gives added value to existing datasets by providing an additional, simple-to-calculate metric for interpreting sediment dynamics.…”

“…Samples pumped at regular intervals (e.g., Beamsley et al, 2001) or better yet, at moments triggered by specific turbidity levels, would provide a more representative basis for calibrating optical and acoustic measurements. Fortunately, analyzing SCI dynamics of additional field sites is already possible, since optical and acoustic instruments are frequently paired together in the field (e.g., Colosimo et al, 2020;de Vet et al, 2020;Flores et al, 2018;Fugate & Friedrichs, 2002;Lin et al, 2020;Moura et al, 2011;Pomeroy et al, 2021;Voulgaris & Meyers, 2004;Zhu et al, 2019). Our approach thus gives added value to existing data sets by providing an additional, simple-to-calculate metric for interpreting sediment dynamics.…”

Cohesive Sediment Modeling in a Shallow Estuary: Model and Environmental Implications of Sediment Parameter Variation

“…In addition, the dominant sediment settling velocity will drive whether the system is predominately depositional or erosional under low wind conditions (Figure 12c); if a supply of fine material ( mm/s) is deposited, it can be exported when it aggregates to slightly larger flocs ( mm/s). In a similar system, wind direction and magnitude, along with intratidal asymmetries in sediment concentration induced by circulation patterns, were observed to play a dominant role in sediment transport over tidal flats (Colosimo et al., 2020). As simulated in a numerical model, wind (yielding wind wave height of 5–10 cm) produced a stabilizing feedback loop on the morphodynamic evolution of a mudflat (Maan et al., 2018).…”

The Properties of Sediment Transport Mechanism in River Mouth of Rupat Strait

“…As presented in Figure 4 and Figure 5, sediment transport at high tide and low tide is asymmetrical. The existence of asymmetries in sediment transport is not only related to the tide-wind interaction, but also related to the intratidal asymmetries in sediment concentration that can be generated by current-topography interaction [2]. Although sediment transport modelling provides us with an understanding of the sediment transport mechanism either due to ambient or anthropogenic forces, intensive monitoring of sediment transport is necessary and this is the target of future research.…”

“…The silting speed is highly dependent on the competition between the forces of the sea (tides), wave, wind, and river discharge. These driving forces sometimes interact with each other to provide sediment transport dynamics that contribute to resuspension and advection properties [2]. The tidal flow also affects the small-scale ripples of the suspended load sediment transport, both indirectly and directly [3].…”