The high energetic wave climate of the North Atlantic Ocean causes important morphological changes at Figueira da Foz coastal system (W Portugal), which is comprised of sandy beaches and the Mondego estuary-inlet. The submerged sandbar at the inlet mouth is highly dynamic inducing short waves shoaling and breaking processes that can entail navigation problems towards the local harbor. Therefore, coastal dredging operations are performed to guarantee safe navigation. Nevertheless, these operations have a limited temporal effectiveness and require a high annual budget to be accomplished. The goal of this research is to seek long-life dredging alternatives using modeling tools (i.e., Delft3D model suite). Delft3D model is used to simulate the morphological evolution of five dredging scenarios during a three-month winter period under three wave climate scenarios. The bed level differences at the dredged area and at the inlet mouth for each scenario are analyzed in comparison with numerical solutions obtained in a reference scenario (i.e., no-dredging). Results highlight morphological changes at the dredged inlet and surrounding areas and their effectiveness in extending the operational lifetime of inlet dredged operations on dredging configuration and wave climate conditions. These findings are the basis for selecting the most suitable dredging scenario to this coastal region under current wave climate conditions.

The in situ measurement of sediment transport in wave‐dominated environments presents significant challenges and currently often relies upon the use of fluorescent sediment tracers. However, this method is constrained by challenges in conducting unbiased and representative sampling, as well as facing overall logistical complexities and labour‐intensive procedures. Whilst other tracer techniques are available, such as using magnetic tracers, their performance in tracking sediment transport has not been quantified. The objective of this study is to assess the effectiveness of magnetic tracers in evaluating net transport rates and tracer dispersal patterns. Conducted in a controlled large wave flume, the experiments simultaneously employed fluorescent and magnetic tracers, allowing a comprehensive comparison of the tracers' dispersion patterns and the net transport rates. Results show that the dispersal of magnetic and fluorescent tracers displays a high degree of spatial coherence in both horizontal and vertical dimensions. Similarly, net transport rates are comparable (<16% difference), both showing net transport in the direction of the wave propagation (towards onshore) driven by non‐linear and streaming effects. Magnetic tracer recovery rate (49%) was lower than for fluorescent tracers (73%) and is attributed to the loss of magnetic ink from particles; an aspect of the magnetic technique that requires improvement. This study therefore indicates that the use of magnetic tracers to quantify sediment transport is an effective method with the advantages of being significantly less labour‐intensive than using the commonly applied fluorescent sediment tracer method.

Fernández-Fernández, S.; Silva, P.A.; Ferreira, C.; Ribeiro, A.S.; Abreu, T.; Romão, S.; Baptista, P.; Fontán-Bouzas, A.; Dias, J.M..; Coelho, C., and Bernardes, C. 2018. Assessment of Dredging/Dumping Scenarios for Figueira da Foz Coastal Region (W Portugal). 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. 1266–1270. Coconut Creek (Florida), ISSN 0749-0208. Figueira da Foz coastal region (W Portugal), that comprises sandy beaches and the Mondego estuary-inlet, is exposed to the high energetic wave climate of the North Atlantic Ocean, which induces important local morphological changes. These changes entail shoaling problems as the formation of a submerse sandbar at the inlet which can block navigation towards local harbor. Therefore, coastal dredging is a non-structural temporal solution for this problem. Nevertheless, dredging activities have an impact on local hydrodynamic processes that should be known beforehand. The aim of this study is to clarify this issue using modeling tools dedicated to help stakeholders in decision making process. For that purpose, Delft3D-WAVE module propagates the most representative regional wave conditions under four dredging scenarios including the respective dump areas. Additionally, Delft3D-FLOW module simulates tidal flows along spring and neap tides. The hydrodynamic parameters, significant wave height, orbital velocity, wave-induced currents, tidal current velocity and total sediment transport are analyzed in comparison with numerical solutions obtained in reference scenario (no dredging and no dumping). The results highlight changes in these hydrodynamic parameters in dredging and dumping areas as well as in surrounded areas. Different scenarios draw a similar change pattern for different parameters, namely a reduction of flow velocity intensity within dredged areas and their increase in adjacent areas. Furthermore, hydrodynamic alterations intensify in response to the increase in significant wave height and wave direction considered. These findings are the basis for understanding the influence of dredging and dumping operations on the hydrodynamic of this coast.

Storm-driven morphodynamics play a key role in the evolution of dredged tidal inlets worldwide, particularly in wave-dominated coasts where navigation channels require continuous maintenance. However, the interaction between storm forcing and dredging interventions remains poorly quantified using long-term observational datasets. This study analyzes storm-driven sediment dynamics at a dredged, wave-dominated tidal inlet using more than 14 years of high-resolution bathymetric surveys and dredging records from the Figueira da Foz inlet (Portugal). Digital Elevation Models derived from repeated surveys reveal the development of a persistent submerged sandbar forming an ebb-delta system in which wave-driven processes exceed tidal forcing, promoting alongshore sediment bypassing.Sediment budgets computed at multiple temporal scales show a marked seasonal contrast. During summer periods, morphological changes are limited and sediment variability is largely controlled by dredging operations. In contrast, winter conditions are dominated by storm-driven sediment fluxes, with individual storm events mobilizing several hundred thousand cubic meters of sediment, frequently exceeding annual dredging volumes. These events drive rapid reorganization of the ebb shoal, channel infilling, and updrift beach progradation, periodically compromising navigation depth within the inlet channel.Despite repeated dredging interventions, the submerged sandbar consistently re-establishes at depths of approximately −5 to −6 m, indicating a strong tendency toward a storm-controlled dynamic equilibrium. These findings demonstrate that storm-driven processes impose fundamental constraints on dredging efficiency and channel maintenance, providing transferable insights for the management of dredged inlet channels and highlighting the need to explicitly account for extreme wave conditions in coastal engineering strategies under energetic wave climates.