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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. [ABSTRACT FROM AUTHOR]

Ferreira, C.; Silva, P.A.; Fernández-Fernández, S.; Baptista, P.; Abreu, T.; Romão, S.; Fontán-Bouzas, A.; Bertin, X., and Garrido, C. 2018. Wave Climate Definition on Modeling Morphological Changes in Figueira da Foz Coastal System (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.1256–1260. Coconut Creek (Florida), ISSN 0749-0208. Field surveys at Figueira da Foz coastal system, a jettied river-mouth located to the W of Portugal, show a high impact of storm events on the morphological evolution of the ebb-tidal delta, with formation of a submerged sandbar and the quick infill of dredged areas. Non-stormy wave conditions produce minor morphological changes. The morphodynamic modeling of this system is being done to support coastal management. The methodology uses Delft3D modeling system that was previously calibrated for this coastal region. Modeling scenarios are set by considering two initial bathymetric situations, i.e., with or without an excavation site resulting from dredging operation. In order to investigate the relations between the computational efficiency and the time series of the input wave data, some tests were performed including a month with a total of 70% of storms and other with 10%, approximately. For each period it was studied the whole month period and only the storms. Numerical results disclose similar patterns of morphological evolution for both complete and storm periods simulated. Nevertheless, the omission of lower wave energy conditions slightly covers up the volume of sediment accretion in the area. This volume of sediment accretion masking effect is higher in the dredging case study, since dredged area acts as a sink of sediment. The results demonstrated that morphodynamic simulations should include the whole set of waves recorded to achieve more accurate estimations of sediment transport rates and corresponding sediment balance. [ABSTRACT FROM AUTHOR]

Jacob, J., Cardeira, S., Rodrigues, M., Bruneau, N., Azevedo, A., Fortunato, A.B., Rosa, M. and Cravo, A., 2013. Experimental and numerical study of the hydrodynamics of the western sector of Ria Formosa. The western sector of Ria Formosa, a lagoon system in the south of Portugal, represents approximately 90% of the total tidal prism of the lagoon and includes three inlets. Two sets of field campaigns to characterize the hydrodynamics of this sector in neap and spring tide conditions were conducted in the autumn of 2011 and spring 2012. The main findings related to the inlets hydrodynamics and water exchanges between the lagoon and the ocean along semi-diurnal tidal cycles are presented. To estimate the relative contribution of the three inlets to the water exchanges between Ria Formosa and the ocean, discharges were evaluated hourly along complete neap and spring semi-diurnal tidal cycles and the tidal prisms computed. In addition, two sea level time series measured in Faro-Olhão inlet and Faro commercial pier were harmonically analyzed. The results were compared with previous studies and used to validate the ELCIRC hydrodynamic model. This model provided additional information about the circulation and tidal prisms and distortion inside the western Ria Formosa. This study confirmed the Faro-Olhão inlet as the main inlet in terms of contribution for the total tidal prism. It is shown that the Ancão inlet lost hydraulic efficiency, contributing less than 6% to the total tidal prism in all situations and the Armona inlet gained efficiency in spring tide and lost efficiency in neap tide. Moreover, the Faro-Olhão inlet exhibits flood prisms higher than ebb prisms under neap and spring tides, suggesting a residual circulation towards the Ancão and Armona inlets. [ABSTRACT FROM AUTHOR]

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This work investigates the recent morphological changes at the inlet of a complex coastal system ( Ria de Aveiro lagoon, Portugal). This study was carried out using bathymetric data analysis and numerical simulations obtained with the 2DH morphodynamic modelling system MORSYS2D. The present simulations considered only tidal forcing, and a sensitivity analysis was performed by tuning the formula used to compute the sediment transports. A non-uniform sediment grain size distribution for the Ria de Aveiro inlet is considered in the numerical simulations, based on surveys performed in this area. The model results are analysed to assess if they resemble the observed trends of erosion and deposition, as calculated from bathymetric data. A quantitative analysis of the differences between the bathymetric changes obtained through surveys and the numerical results over a period of 3 years considering different sediment transport formulations shows that the formulations of Ackers and White () and Engelund and Hansen () are the ones that best describe the morphodynamic changes driven by tides in the Ria de Aveiro inlet. [ABSTRACT FROM AUTHOR]

This work describes the application of hydrodynamic (ELCIRC) and transport (VELA and VELApart) models to the Ria Formosa lagoon (Portugal) to study the impact of the relocation of the Ancão Inlet. Located in the south of Portugal, this lagoon is a mesotidal barrier island system that communicates with the sea through 6 inlets. The Old Ancão Inlet was artificially closed and the New Ancão Inlet was relocated into a westward position. This work investigates the hydrodynamic patterns and the potential pathways of tracers in Ria Formosa in two distinct configurations: before and after the Ancão Inlet relocation. The hydrodynamic model was successfully calibrated and validated against elevation, velocity and inlet discharges data, accurately reproducing the tidal propagation. The inlet relocation increases the magnitude of tidal currents, residual velocities and the tidal prism across the bar, suggesting a better stability. The tracers transport simulations suggest enhanced water exchanges through the Ancão Inlet and smaller residence times in the western part of Ria Formosa with the present configuration. Overall, it is concluded that the Ancão Inlet relocation had a positive contribution towards increasing the water renewal of the western part of the lagoon, thus decreasing its vulnerability to pollution. [Copyright &y& Elsevier]

The objective of this work is to determine the relative importance of different processes (swash, overwash, aeolian, and lagoon) affecting sediment dynamics in barriers with frequent overwash. Aerial photographs, topographic surveys (with real-time kinematic global positional system), and sample collection were undertaken on Barreta Island (Ria Formosa barrier islands, Portugal). Wave and tidal data were also analysed during a 3-year monitoring period (2001-2004). This 3-year period represents the typical wave conditions of this region. Historical barrier evolution was characterised for the 1947-2001 period. Up until 1996, the supratidal barrier changed from barred sand to fully developed dunes. In 2001, a wide washover plain had developed and an updrift tidal inlet (Ancão Inlet) was migrating toward the study area. Between 2001 and 2004, the study area had three geomorphological sectors. Sector A (westernmost) showed the widest beach berms that developed because of welding of swash bars of Ancão Inlet. Sector B had the widest washover and developed embryonic dunes with well-sorted medium sands. In sector C (easternmost), overwash was more frequent, and induced the deposition of 57 m3/m of sediments (the coarsest of the barrier). Globally, barrier volume variation was mostly due to swash (83%); however, net barrier accretion was 88% induced by overwash. Barrier volume variation was more related to Ancão Inlet evolution than to the seasonality of wave climate. A four-stage conceptual model of barrier evolution under frequent overwash is presented: beach erosion; dune destruction, and formation of washover plain; frequent overwash; and dune development. [ABSTRACT FROM AUTHOR]

Three sediment transport studies using tracers were performed at Ancão Inlet (southern Portugal). The objectives of the experiments were to understand the sediment transport pathways and to determine their magnitudes on the updrift margin of an inlet. In order to apply the traditionally used Space Integration Methodology to the tracer experiments, adaptations were required. The study area was divided into four morphologically defined sectors and this was found to be a key factor for the applicability of tracers in a complex area. The four sectors are as follows: sector A is the straight part of the updrift beach; sector B is the upper area of the swash platform; sector C is the lower area of the swash platform; and sector D represents the inner parts of the inlet margin. The integrated analysis of all collected data (forcing mechanisms, tracer distribution and topographic evolution) led to the determination of the sediment pathways. A semi-quantitative conceptual model was developed in order to explain the sediment transport pathways and magnitudes that a known mass of sediment would follow after arriving at the swash platform. It was found that the areas with the largest sediment accumulation were sectors B and C, while almost no sediment was retained in sector D, which experienced significant erosion. According to the model, 53% of the initial mass of sediments remain in the system after two tidal cycles. It is hypothesised that sediment losses are caused by sediment transport towards the ebb delta and by sediment bypassing occurring from the ebb delta to the downdrift beach through swash bar processes. The herein defined conceptual model represents a useful tool that could be applied to other tidal inlets under similar conditions, facilitating sediment budget studies around tidal inlets. [Copyright &y& Elsevier]