Se realizaron 14 campañas topo-batimétricas desde la playa emergida hasta los 15 m
de profundidad, a lo largo de 1 km en la playa de Castelldefels (Delta del Llobregat,
Barcelona) durante el periodo 2011-2020. Se analizan las variaciones morfológicas que tienen
lugar, los cambios volumétricos y sus posibles implicaciones en los intercambios sedimentarios
en el perfil litoral. Los principales cambios morfológicos están causados por los
desplazamientos transversales de las barras de arena, generalmente hacia tierra durante
condiciones de buen tiempo y hacia mayor profundidad durante las tormentas más fuertes. Los
cambios volumétricos sugieren que el retroceso de la línea de costa durante la última década
aporta sedimento a la parte superior de la playa sumergida, mientras que los eventos más
extremos producen una transferencia de sedimento hacia la plataforma continental, que
podrían ser parcialmente irrecuperables para la dinámica litoral. El balance sedimentario
resultante es negativo, Postprint (updated version)

Mean sea-level rise (MSLR) will induce shoreline recession, increasing the stress on coastal systems of high socio-economic and environmental values. Localized mega-nourishments are meant to alleviate erosion problems by diffusing alongshore over decades and thus feeding adjacent beaches. The 21-st century morphological evolution of the Delfland coast, where the Sand Engine mega-nourishment was built in 2011, was simulated with the Q2Dmorfo model to assess the Sand Engine capacity to protect the area against the effects of MSLR. The calibrated and validated model was forced with historical wave and sea-level data and MSLR projections until 2100 corresponding to different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5). Results show that the Sand Engine diffusive trend will continue in forthcoming decades, with the feeding effect to adjacent beaches being less noticeable from 2050 onward. Superimposed to this alongshore diffusion, MSLR causes the shoreline to recede because of both passive-flooding and a net offshore sediment transport produced by wave reshaping and gravity. The existing feeding asymmetry enforces more sediment transport to the NE than to the SW, causing the former to remain stable whilst the SW shoreline retreats significantly, especially from 2050 onward. Sediment from the Sand Engine does not reach the beaches located more than 6 km to the SW, with a strong shoreline and profile recession in that area, as well as dune erosion. The uncertainties in the results are dominated by those related to the free model parameters up to 2050 whilst uncertainties in MSLR projections prevail from 2050 to 2100., This work has been funded by the Spanish government through the research projects RTI2018-093941-B-C31 and RTI2018-093941-B-C33 (MINECO/FEDER), Peer Reviewed, Postprint (published version)

The quantification of sediment exchanges between the beach and the lower shoreface, although being still poorly understood, is required to adequately forecast long-term coastal evolution. The effect of extreme storms on the morphodynamics of the nearshore and the sediment budget of the coastal zone seems to be strongly conditioned by local parameters, which should be incorporated into studies of medium- and long-term coastal evolution. In the upper shoreface, the dynamics of shore-parallel bars in sandy coasts have been extensively studied, but their implications for the sediment budget remain controversial as it is unclear whether their evolution simply represents a morphological change or denotes an escape of sediment from the upper shoreface. In order to provide new knowledge to address these questions, fifteen topo-bathymetric surveys that extend from the emerged beach to 15 m water depth were carried out along 1 km of Castelldefels beach (Llobregat Delta, Barcelona, western Mediterranean Sea) during the period 2011–2022. Morphological variations on the shoreface are studied, volumetric changes are estimated and implications on sedimentary exchanges in the littoral profile are inferred. The largest morphological (volumetric) changes are caused by cross-shore displacements of the nearshore bars, usually onshore during fair-weather conditions and offshore during storms. Volumetric changes suggest that shoreline retreat and the erosion of the shallow section of the profile during the last decade provides sediment to both the distal upper shoreface and the lower shoreface. The resulting sediment budget in the profile is almost zero in absence of extreme storms, but becomes highly negative when including extreme storms events that cause a net offshore transfer of sediment from the upper to the lower shoreface and, probably, the inner shelf. The characteristics of the study area (morphology, sediments, waves, tides) and in-situ hydrodynamic measurements at the lower shoreface suggest that the main potential onshore transport mechanisms (velocity and acceleration skewness during low-mid energy event) are small, making a significant transfer of sediment from the lower shoreface towards the shallow beach area unlikely at interannual scales. Thus, the study area is an example of low-lying coastal stretch in which the potential long-term shoreline retreat caused by sea level rise cannot be fully compensated by the sediment supplied from the lower shoreface. Other mechanisms, such as sediment supplied by longshore transport, are needed to counteract this trend., This work has been carried out in the framework of the MOCCA (RTI2018-093941-B-C2/C3), MOLLY (PID2021-124272OB-C21/C22), LAMARCA (PID2021-123352OB-C31), TECH2COAST (TED2021- 130949B-I00) and SOLDEMOR (TED2021-130321B-I00) research pro- jects funded by the Spanish Ministry of Science, Innovation and Uni- versities – National Research Agency and EU “NextGenerationEU/PRTR. Puertos del Estado provides the wave data and the Port of Barcelona provides the bathymetric data of July 2020. This work is contributing to the ICM ‘Center of Excellence’ Severo Ochoa (CEX2019-000928-S)., Peer Reviewed, Postprint (published version)

24 pages, 15 figures, 9 tables, 1 appendix, A new approach to infer the bathymetry from coastal video monitoring systems is presented. The methodology uses principal component analysis of the Hilbert transform of video images to obtain the components of the wave propagation field and their corresponding frequency and wavenumber. Incident and reflected constituents and subharmonics components are also found. Local water depth is then successfully estimated through wave dispersion relationship. The method is first applied to monochromatic and polychromatic synthetic wave trains propagated using linear wave theory over an alongshore uniform bathymetry in order to analyze the influence of different parameters on the results. To assess the ability of the approach to infer the bathymetry under more realistic conditions and to explore the influence of other parameters, nonlinear wave propagation is also performed using a fully nonlinear Boussinesq-type model over a complex bathymetry. In the synthetic cases, the relative root mean square error obtained in bathymetry recovery (for water depths 0.75m⩽h⩽8.0m ) ranges from ∼1% to ∼3% for infinitesimal-amplitude wave cases (monochromatic or polychromatic) to ∼15% in the most complex case (nonlinear polychromatic waves). Finally, the new methodology is satisfactorily validated through a real field site vide, This research was funded by the Spanish Government (MINECO/MICINN/FEDER) grant numbers CTM2015-66225-C2-1-P, CTM2015-66225-C2-2-P, RTI2018-093941-B-C31, RTI2018-093941-B-C32, and RTI2018-093941-B-C33, Peer Reviewed

This work analyzes the coastal impacts of the combined effect of extreme waves and sea level extremes, including surges and projected mean sea level rise in Bocagrande, Cartagena (Colombia). Extreme waves are assessed from a wave reanalysis that are propagated from deep waters to the beach considering the hydrodynamic processes and taking into account the interaction between waves and the coastal elevation within the study area. First, we consider present sea level, storm surges and waves affecting the area. Next, we analyze the effect of sea level rise according to a moderate (RCP4.5) climate change scenario for the 21st century (years 2025, 2050, 2075, and 2100). The most pessimistic scenario (year 2100) yields a percentage of flooded area of 97.2%, thus revealing the major threat that represents sea level rise for coastal areas in the Caribbean Sea., This work was supported by COLCIENCIAS (Departamento Administrativo de Ciencia, Tecnología e Innovación) through of convocatoria 727 and from the Spanish Government MICINN/FEDER through projects MUSA (CTM2015-66225-C2-2-P) and MOCCA (RTI2018-093941-B-C31). The authors acknowledge the financial support from the Spanish Government MICINN/FEDER through projects MUSA (CTM2015-66225-C2-2-P) and MOCCA (RTI2018-093941-B-C31). AO-R is supported by a grant from Colombian COLCIENCIAS (Convocatoria 727). JS thanks the financial support by the Netherlands Scientific Research Foundation (NWO) through the VIDI grant number 864.13.011 awarded to C. A. Katsman. IH-C acknowledges the Vicenç Mut contract funded by the Government of the Balearic Island. This work was partially performed while AO was a visiting scientist at the Earth, Environmental and Planetary Sciences Department at Brown University through a Ministerio de Ciencia, Innovación y Universidades fellowship (PRX18/00218).

The ocean component and coastal impacts of Storm Gloria, which hit the western Mediterranean between 20 and 23 January 2020, are investigated with a numerical simulation of the storm surges and wind waves. Storm Gloria caused severe damages and beat several historical records, such as significant wave height or 24 h accumulated precipitation. The storm surge that developed along the eastern coasts of the Iberian Peninsula, reaching values of up to 1 m, was accompanied by wind waves with a significant wave height of up to 8 m. Along the coasts of the Balearic Islands, the storm footprint was characterised by a negligible storm surge and the impacts were caused by large waves. The comparison to historical records reveals that Storm Gloria is one of the most intense among the events in the region during the last decades and that the waves' direction was particularly unusual. Our simulation permits quantification of the role of the different forcings in generating the storm surge. Also, the high spatial grid resolution down to 30 m over the Ebro Delta allows determination of the extent of the flooding caused by the storm surge. We also simulate the overtopping caused by high wind waves that affected a rocky coast of high cliffs (∼15 m) on the eastern coast of Mallorca., This study was supported by the FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación through the MOCCA project (grant no. RTI2018-093941-B-C31). Diego S. Carrió was supported by the ARC Centre of Excellence for Climate Extremes (grant no. CEI70100023). Marta Marcos was supported by the Ministerio de Ciencia e Innovación and la Agencia Estatal de Investigación through grant no. IED2019-000985-I. Angel Amores was funded by the Conselleria d'Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (grant no. PD/011/2019).

Influence of frontal dynamics on phytoplankton distribution and composition was studied combining in situ observations and Lagrangian computations from altimetry satellite derived currents. Four transects during the SHEBEX cruise (May 2015) over the Western Mediterranean were examined identifying a region with high spatial variability in the dynamical and biogeochemical properties. The dynamical situation unraveled from the Lagrangian analysis is dominated by filaments originated by an anticyclonic–cyclonic eddy interaction that organize the transport, modifying the biogeochemical properties of the water column and shaping the satellite derived surface Chlorophyll a (chla) distribution. The properties of the water column have been analyzed in relation to the dynamical properties of the filaments showing that local variation of the mixed layer and nutricline depths are correlated with the spatial variability of finite size Lyapunov exponents. Furthermore, the composition of phytoplankton community was studied regarding the path-accumulated properties of the flow during the formation of the filaments. In this regard new metrics accounting the Lagrangian evolution of the turbulent and topological properties of the flow along fluid parcel trajectories have been developed. Here we provide observational evidence that fluid parcels associated with high Lagrangian turbulent kinetic energy and Lagrangian positive vorticity host higher presence of larger pennate diatoms (i.e. Pseudo-nitzschia spp). Our findings indicate that the combination of these diagnostics provides an improved description of the turbulent dynamics showing that the Lagrangian properties of the flow have important biological consequences for phytoplankton to high ecological levels., I. Hernandez-Carrasco acknowledges the Vicenç Mut contract funded by the Government of the Balearic Islands, Spain and the European Social Fund (ESF) Operational Programme and the financial support from the Fundacion Universidad Empresa de las Islas Baleares, Spain through project ALERTA (REF-190121). We thank the officers and crew of the R/V SOCIB for logistical support, and technology development facility (ETD) from SOCIB for assistance in the field and A. Massanet for assistance with sampling and in the laboratory. Authors acknowledge the financial support from the Spanish Government MICINN/FEDER through projects MUSA (CTM2015-66225-C2-2-P) and MOCCA (RTI2018-093941-B-C31).

Each file contains significant wave height (Hs), mean wave period (Tm_01) (Tmm_10), mean wave direction (θ_m), latitude, longitude and time for a specific year. Each file in NetCDF format is around 1GB size containing the above data every 6 hours at 00h, 06h, 12h and 18h. Data cover from January, 1^st 1958 to December, 〖31〗^st 2017 on a 229 x101 mesh nodes with a resolution of 11.8 km x 11.4 km. Bottom left corner coordinates are -84.52° W; 8.1° N., AOR is supported by COLCIENCIAS (Departamento Administrativo de Ciencia, Tecnología e Innovación) through a PhD grant from “Convocatoria 727” and from a POGO fellowship at the Mediterranean Institute for Advanced Studies. Authors acknowledge financial support from the Spanish Government MICINN/FEDER through MOCCA Project (RTI2018-093941-B-C31)., Peer reviewed

This article presents a 60 years wave hindcast from 1958 to 2017, covering the Colombian Caribbean basin. Each output consists on 6-hour field of significant wave height , mean wave period , and mean direction with a resolution of 11.8 11.4 . The simulation was performed using SWAN model forced with JRA-55 wind fields. Model data is validated against NOAA buoy 42058 located in the central Caribbean. The resolution and time spam of this database allows to perform either coastal engineering projects as well as to perform research in seasonal and interannual wave climate variability including large return periods to evaluate coastal vulnerability., AOR is supported by COLCIENCIAS (Departamento Administrativo de Ciencia, Tecnología e Innovación) through a PhD grant from “Convocatoria 727” and from a POGO fellowship at the Mediterranean Institute for Advanced Studies. Authors acknowledge financial support from the Spanish Government MICINN/FEDER through MOCCA Project (RTI2018-093941-B-C31)., Peer reviewed

205 pages, 12 figures, 1 table, 3 appendixes.-- Data Availability Statement: All data are accessible from https://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/, https://www.cpc.ncep.noaa.gov/data/teledoc/telecontents.shtml and from https://resources.marine.copernicus.eu/?option=com_csw&view=details&product_id=SEALEVEL_MED_PHY_L4_REP_OBSERVATIONS_008_051, Effects of wind and waves on the surface dynamics of the Mediterranean Sea are assessed using a modified Ekman model including a Stokes-Coriolis force in the momentum equation. Using 25 years of observations, we documented intermittent but recurrent episodes during which Ekman and Stokes currents substantially modulate the total mesoscale dynamics by two nonexclusive mechanisms: (a) by providing a vigorous input of momentum (e.g., where regional winds are stronger) and/or (b) by opposing forces to the main direction of the geostrophic component. To properly characterize the occurrence and variability of these dynamical regimes, we perform an objective classification combining self-organizing maps and wavelet coherence analyses. It allows proposing a new regional classification of the Mediterranean Sea based on the respective contributions of wind, wave, and geostrophic components to the total mesoscale surface dynamics. We found that the effects of wind and waves are more prominent in the northwestern Mediterranean, while the southwestern and eastern basins are mainly dominated by the geostrophic component. The resulting temporal variability patterns show a strong seasonal signal and cycles of 5–6 years in the total kinetic energy arising from both geostrophic and ageostrophic components. Moreover, the whole basin, specially the regions characterized by strong wind- and wave-induced currents, shows a characteristic period of variability at 5 years. This can be related to climate modes of variability. Regional trends in the geostrophic and ageostrophic currents show an intensification of 0.058 ± 1.43 · 10−5 cm/s per year, Authors acknowledge financial support from MINECO/FEDER through projects MOCCA (RTI2018-093941-B-C31) and from the Balearic Islands Goverment Project ADAPTA. V. Morales-Márquez is supported by an FPI grant from the Ministerio de Ciencia, Innovación y Universidades. I. Hernandez-Carrasco acknowledges the Vicenç Mut contract funded by the Government of the Balearic Island and the European Social Fund (ESF) Operational Programme and the financial support from the Fundacion Universidad Empresa de las Islas Baleares, Spain, through project ALERTA (REF-190121). V. Rossi acknowledges financial support from the European project SEAMoBB, funded by ERA-Net Mar-TERA and managed by ANR (number ANR_17_MART-0001_01, P.I.: A.C.). This work was partially performed while V. Morales-Márquez was staying in MIO (Marseille, France) with the support of FPI grant from the Ministerio de Ciencia, Innovación y Universidades. In addition, this work was carried out in part when A. Orfila was a visiting scientist at the Earth, Environmental and Planetary Sciences Department at Brown University through a Ministerio de Ciencia, Innovación y Universidades fellowship (PRX18/00218), With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S), Peer reviewed

Sea-level rise induces a permanent loss of land with widespread ecological and economic impacts, most evident in urban and densely populated areas. Potential coastline retreat combined with waves and storm surges will result in more severe damages for coastal zones, especially over insular systems. In this paper, we quantify the effects of sea-level rise in terms of potential coastal flooding and potential beach erosion, along the coasts of the Balearic Islands (Western Mediterranean Sea), during the twenty-first century. We map projected flooded areas under two climate-change-driven mean sea-level rise scenarios (RCP4.5 and RCP8.5), together with the impact of an extreme event defined by the 100-year return level of joint storm surges and waves. We quantify shoreline retreat of sandy beaches forced by the sea-level rise (scenarios RCP4.5 and RCP8.5) and the continuous action of storm surges and waves (modeled by synthetic time series). We estimate touristic recreational services decrease of sandy beaches caused by the obtained shoreline retreat, in monetary terms. According to our calculations, permanent flooding by the end of our century will extend 7.8–27.7 km2 under the RCP4.5 scenario (mean sea-level rise between 32 and 80 cm by 2100), and up to 10.9–36.5 km2 under RCP8.5 (mean sea-level rise between 46 and 103 cm by 2100). Some beaches will lose more than 50% of their surface by the end of the century: 20–50% of them under RCP4.5 scenario and 25–60% under RCP8.5 one. Loss of touristic recreational services could represent a gross domestic product (GDP) loss up to 7.2% with respect to the 2019 GDP., This study was supported by PIMA ADAPTA-Balears Project funded by Conselleria de Transició Energética, Sectors Productius i Memòria Democràtica, Govern Balear, and by the FEDER/Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación through the MOCCA project (RTI2018-093941-B-C31 MINECO-AEI-UE-FEDER). LG-P is also funded by the CGL2016-79246-P MINECO-AEI-UE-FEDER project. PL was supported by the FPU19/03081 grant from Ministerio de Ciencia, Innovación y Universidades of Spain.

The Maldives, with one of the lowest average land elevations above present-day mean sea level, is among the world regions that will be the most impacted by mean sea-level rise and marine extreme events induced by climate change. Yet, the lack of regional and local information on marine drivers is a major drawback that coastal decision-makers face to anticipate the impacts of climate change along the Maldivian coastlines. In this study we focus on wind-waves, the main driver of extremes causing coastal flooding in the region. We dynamically downscale large-scale fields from global wave models, providing a valuable source of climate information along the coastlines with spatial resolution down to 500 m. This dataset serves to characterise the wave climate around the Maldives, with applications in regional development and land reclamation, and is also an essential input for local flood hazard modelling. We illustrate this with a case study of HA Hoarafushi, an atoll island where local topo-bathymetry is available. This island is exposed to the highest incoming waves in the archipelago and recently saw development of an airport island on its reef via land reclamation. Regional waves are propagated toward the shoreline using a phase-resolving model and coastal inundation is simulated under different mean sea-level rise conditions of up to 1 m above present-day mean sea level. The results are represented as risk maps with different hazard levels gathering inundation depth and speed, providing a clear evidence of the impacts of the sea level rise combined with extreme wave events., This study was supported by the FEDER/Ministerio de Ciencia, Innovación y Universidades Agencia Estatal de Investigación through the MOCCA project (grant no. RTI2018-093941-B-C31) and by the INSeaPTION Project that is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by Ministerio de Economía, Industria y Competitividad Agencia Estatal de Investigación (ES) (grant no. PCIN-2017-038), BMBF (DE), NOW (NL), and ANR (FR) with co-funding by the European Union (Grant 690462). This research has been also supported by the ANR project Storisk supported by the French Research Agency. AA was funded by the Conselleria d'Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (grant no. PD/011/2019). MM was supported by the Ministerio de Ciencia e Innovación and la Agencia Estatal de Investigación through grant no. IED2019-000985-I.

The use of high-frequency radar (HFR) data is increasing worldwide for different applications in the field of operational oceanography and data assimilation, as it provides real-time coastal surface currents at high temporal and spatial resolution. In this work, a Lagrangian-based, empirical, real-time, short-term prediction (L-STP) system is presented in order to provide short-term forecasts of up to 48 h of ocean currents. The method is based on finding historical analogs of Lagrangian trajectories obtained from HFR surface currents. Then, assuming that the present state will follow the same temporal evolution as the historical analog, we perform the forecast. The method is applied to two HFR systems covering two areas with different dynamical characteristics: the southeast Bay of Biscay and the central Red Sea. A comparison of the L-STP methodology with predictions based on persistence and reference fields is performed in order to quantify the error introduced by this approach. Furthermore, a sensitivity analysis has been conducted to determine the limit of applicability of the methodology regarding the temporal horizon of Lagrangian prediction. A real-time skill score has been developed using the results of this analysis, which allows for the identification of periods when the short-term prediction performance is more likely to be low, and persistence can be used as a better predictor for the future currents., This research has been supported by EU Horizon 2020 (grant nos. LIFE15 ENV/ES/000252, 654410, and 871153) and by the Spanish MINECO (grant no. 256 RTI2018-093941-B-C31 co-financed with FEDER funds).

This study provides a literature-based comparative assessment of uncertainties and biases in global to world-regional scale assessments of current and future coastal flood risks, considering mean and extreme sea-level hazards, the propagation of these into the floodplain, people and coastal assets exposed, and their vulnerability. Globally, by far the largest bias is introduced by not considering human adaptation, which can lead to an overestimation of coastal flood risk in 2100 by up to factor 1300. But even when considering adaptation, uncertainties in how coastal societies will adapt to sea-level rise dominate with a factor of up to 27 all other uncertainties. Other large uncertainties that have been quantified globally are associated with socio-economic development (factors 2.3–5.8), digital elevation data (factors 1.2–3.8), ice sheet models (factor 1.6–3.8) and greenhouse gas emissions (factors 1.6–2.1). Local uncertainties that stand out but have not been quantified globally, relate to depth-damage functions, defense failure mechanisms, surge and wave heights in areas affected by tropical cyclones (in particular for large return periods), as well as nearshore interactions between mean sea-levels, storm surges, tides and waves. Advancing the state-of-the-art requires analyzing and reporting more comprehensively on underlying uncertainties, including those in data, methods and adaptation scenarios. Epistemic uncertainties in digital elevation, coastal protection levels and depth-damage functions would be best reduced through open community-based efforts, in which many scholars work together in collecting and validating these data., DL, GLC, JH, MM, RvdW have been partially supported by the ERA4CS Project INSeaPTION (grant 01LS1703A) and DL and JH by the Project ISIPEDIA (grant 01LS1711C). Both Projects are part of ERA4CS, an ERA-NET initiated by JPI Climate and funded by FORMAS (SE), BMBF (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462). DL, JH, RN and RvdW have received funding from the PROTECT project (grant 869304), and DL and JH from the COACCH project (grant 776479), both funded under the European Union's Horizon 2020 Research and Innovation Programme. ATV, CW, DL and JH have been supported by the Deutsche Forschungsgemeinschaft (DFG) through the SEASCAPE II project, which is part of the Special Priority Program 1889 Regional Sea Level Change and Society. MM has been partially supported by the MOCCA project (grant RTI2018-093941-B-C31). TW was partially supported by the National Aeronautics and Space Administration (NASA) under the New (Early Career) Investigator Program in Earth Science (grant number: 80NSSC18K0743) and MH was partially supported by the Australian Government National Environmental Science Program Earth Systems and Climate Change Hub. PJW has been supported by the Dutch Research Council (NWO) in the form of a VIDI grant (grant no. 016.161.324).

A novel approach for estimating wave energy dissipation on a coral reef barrier is studied using X-Band radar technology. The prominent features of coral reefs, including the delineation of reef morphological structure, wave energy dissipation and wave transformation processes are obtained in a reef lagoon in San Andres Island, Colombia. Results show that reef attenuates incident waves by approximately 75% due to both frictional processes and wave breaking, with an equivalent bottom roughness of 0.20 m and a wave friction factor of 0.18. These parameters are comparable with estimates reported in other shallow coral reef lagoons as well as at seagrass meadows obtained using in-situ measurements. Also, the mean height of the reef elements Hbed and its standard deviation σb are also estimated in the entire radar coverage area. Hbed and σb (0.5 and 7.66 cm respectively) are in the same order of magnitude of measured data reported by previous studies and in good agreement with the geometric parameters proposed by in-canopy flow models for branched species, such as Stylophora and Pocillopora, which are also common in the coral carpets of San Andres Island. This work proposes a completely novel use for X-Band radars by describing prominent features in barrier-reef systems including the delineation of the reef structure and wave energy dissipation., This research has been possible thanks to financial support from Colombian Science and Technology Ministry Projects FP44842-144-2016 (Wave propagation and sediment transport on coral reefs) and 0376-2013 (Developing and modeling of a sea state sensor through the processing of radar signals). Wendy Navarro was supported by Universidad del Norte, COLCIENCIAS (Call 757) and iCOOP+2016 (CSIC) fellowships. Andres Orejarena-Rondon was supported by COLCIENCIAS (Call 727). The authors thank Universidad del Norte for providing equipment and the Colombian Naval Academy Almirante Padilla (Dept. of Oceanography) for field support. Alejandro Orfila acknowledges financial support from the Spanish Government MICINN/FEDER through MOCCA Project (RTI2018-093941-B-C31)., Peer reviewed

Medicanes, for Mediterranean hurricanes, are mesoscale cyclones with morphological and physical characteristics similar to tropical cyclones. Although less intense, smaller, and rarer than their Atlantic counterparts, medicanes are very hazardous events threatening islands and continental coasts within the Mediterranean Sea. The latest strong episode, Medicane Ianos (September 2020), resulted in severe damages in Greece and several casualties. This work investigates the oceanic response to these extreme events along the Mediterranean coasts under present-day and future (late 21st century) climate conditions. To this end, a coupled hydrodynamic-wave model is used to simulate both storm surges and wind-waves generation and propagation in the Mediterranean Sea at high resolution (∼2 km) along the coastlines. A data set of thousands of medicanes synthetically generated from 20 global climate models and two atmospheric reanalyses is used to derive the atmospheric forcing fields. Regional coastal hazards assessment is performed for the present and future climates. For the first period, highest medicane-induced waves are found in the central and the southwest part of the western Mediterranean, while greatest storm surges are found in the Adriatic Sea and regions characterized by wide and gently sloping continental shelves. Results obtained for future changes show amplitudes generally smaller than the associated uncertainty due to limited agreement among models (especially for coastal elevation). Though, model consensus is reached (60–75%) and relative intensity change is significant (10–20%) at some locations (e.g., 1 m increase of medicane-induced significant wave height on average for south coasts of Sicilia)., This study was supported by the Project RTI2018-093941-B-C31 funded by MCIN/AEI/10.13039/501100011033/and by FEDER Una manera de hacer Europa. Tim Toomey acknowledges an FPI grant associated with the MOCCA project (Grant No. PRE2019-088046). Angel Amores was funded by the Conselleria d’Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (Grant No. PD/011/2019). Marta Marcos was supported by the Ministerio de Ciencia e Innovación and la Agencia Estatal de Investigación through Grant No. IED2019-000985-I. Romu Romero was funded by FEDER/Ministerio de Ciencia, Innovación y Universidades—Agencia Estatal de Investigación through the COASTEPS project (Grant No. CGL2017-82868-R).

This study was supported by the MOCCA project Grant RTI2018-093941-B-C31 funded by MCIN/AEI/ 10.13039/501100011033 and by "ERDF A way of making Europe". It was also supported by grants PGC2018-099285-B-C21 and PGC2018-099285-B-C22 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” NextGenerationEU/PRTR. Angel Amores was funded by the Conselleria d’Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (Grant No. PD/011/2019). Daniel Argüeso was funded by Spanish Ministry of Science and Innovation through the EPICC Project (PID2019-105253RJ-I00) and the Beatriz Galindo Programme (BG20/00078)., No

On 15 January 2022, around 4:30 UTC the eruption of the Hunga-Tonga volcano, in the South Pacific Ocean, generated a violent underwater explosion. In addition to tsunami waves that affected the Pacific coasts, the eruption created atmospheric pressure disturbances that spread out in the form of Lamb waves. The associated atmospheric pressure oscillations were detected in high-frequency in-situ observations all over the globe. Here we take advantage of the similarities in the propagation and characteristics between atmospheric Lamb waves and long ocean waves and we use a 2DH ocean numerical model to simulate the phenomenon. We compare the outputs of the numerical simulation with in-situ atmospheric pressure records and with remote satellite observations. The signal in the model matches the observed atmospheric pressure perturbations and reveals an excellent agreement in the wave arrival time between model and observations at hundreds of locations at different distances from the origin., This study was supported by the MOCCA project Grant RTI2018-093941-B-C31 funded by MCIN/AEI/ 10.13039/501100011033 and by "ERDF A way of making Europe". It was also supported by grants PGC2018-099285-B-C21 and PGC2018-099285-B-C22 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” NextGenerationEU/PRTR. Angel Amores was funded by the Conselleria d’Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (Grant No. PD/011/2019). Daniel Argüeso was funded by Spanish Ministry of Science and Innovation through the EPICC Project (PID2019-105253RJ-I00) and the Beatriz Galindo Programme (BG20/00078).

Amores, Angel; Marcos, Marta; Le Cozannet, Gonéri; Hinkel, Jochen. Author Correction: Coastal flooding and mean sea-level rise allowances in atoll island. Scientific Reports 12: 2523 (2022). https://doi.org/10.1038/s41598-022-06548-2 . http://hdl.handle.net/10261/272773, Atoll islands are among the places most vulnerable to climate change due to their low elevation above mean sea level. Even today, some of these islands suffer from severe flooding generated by wind-waves, that will be exacerbated with mean sea-level rise. Wave-induced flooding is a complex physical process that requires computationally-expensive numerical models to be reliably estimated, thus limiting its application to single island case studies. Here we present a new model-based parameterisation for wave setup and a set of numerical simulations for the wave-induced flooding in coral reef islands as a function of their morphology, the Manning friction coefficient, wave characteristics and projected mean sea level that can be used for rapid, broad scale (e.g. entire atoll island nations) flood risk assessments. We apply this new approach to the Maldives to compute the increase in wave hazard due to mean sea-level rise, as well as the change in island elevation or coastal protection required to keep wave-induced flooding constant. While future flooding in the Maldives is projected to increase drastically due to sea-level rise, we show that similar impacts in nearby islands can occur decades apart depending on the exposure to waves and the topobathymetry of each island. Such assessment can be useful to determine on which islands adaptation is most urgently needed., This study was supported by the project RTI2018-093941-B-C31 supported by MCIN/ AEI 10.13039/501100011033 and by FEDER Una manera de hacer Europa and by the INSeaPTION Project that is part of ERA4CS, an ERANET initiated by JPI Climate, and funded by Ministerio de Economía, Industria y Competitividad-Agencia Estatal de Investigación (ES) (Grant number PCIN-2017-038), BMBF (DE), NOW (NL) and ANR (FR) with co-funding by the European Union (Grant 690462). Angel Amores was funded by the Conselleria d’Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (Grant no. PD/011/2019). The authors are grateful to Dr. Rodrigo Pedreros for his help in the interpretation of the results, to Benoit Meyssignac for sharing SLR reconstruction data, Aurélie Maspataud for the bathymetry and Rémi Thiéblemont for contributions in the development of the SLR projection codes. The wave setup and wave-induced flooding simulations can be downloaded from https://doi.org/10.5281/zenodo.5521394., Peer reviewed

In the Mediterranean Sea, coastal extreme sea levels are mainly caused by storm surges driven by atmospheric pressure and surface winds from extratropical cyclones. In addition, wind-waves generated by the same atmospheric perturbations may also contribute to coastal extremes through wave setup (temporal rise above the mean sea level due to dissipation and breaking of waves in shallow waters close to the shore). This study investigates the spatial and temporal variability of coastal extreme sea levels in the Mediterranean basin, using a new ocean hindcast generated with a coupled hydrodynamic-wave model that simulates storm surges and wind-waves. The numerical simulation covers the period 1950-2021 with high temporal sampling (1h) and at unprecedented spatial resolution for a basin scale analysis, that reaches 200 m along the coastlines. Coastal storm surges and wave heights are validated with available observations (tide gauges, waves buoys and satellites). Comparison against tide gauges shows an average RMSE of 7.5 cm (7.7 cm for extreme events) and mean linear correlation of 0.64 for the whole period. Similarly, comparison of simulated and observed significant wave height shows good agreement, with RMSE lower than 0.25 m and a coefficient correlation as high as 0.95. The results confirm that coastal extreme sea levels are more likely to be located in regions with wide continental shelves favouring the wind contribution to storm surges along with shallow waters that favour wave setup induced by depth-breaking. The contribution of waves to coastal extreme sea levels has been quantified, using the hindcast in combination with an uncoupled simulation and has been shown to be significant, with an assessed wave setup spatial footprint at regional scale and observed maximum sea levels increased by up to 120% in the presence of waves., This study was supported by the Project RTI2018-093941-B-C31 funded by MCIN/AEI/10.13039/501100011033/and by FEDER Una manera de hacer Europa. Tim Toomey acknowledges an FPI grant associated with the MOCCA project (grant number PRE2019-088046). Angel Amores was funded by the Conselleria d’Educació, Universitat i Recerca del Govern Balear through the Direcció General de Política Universitària i Recerca and by the Fondo Social Europeo for the period 2014–2020 (grant no. PD/011/2019).

The Tumaco multivariate index (TMI) is a multidecadal monthly index constructed with unique time series of sea surface temperature, surface air temperature and rain measured at Tumaco bay, in the southern Pacific coast of Colombia, and available since 1961. In this work, this index is re-evaluated after the addition of in situ sea level data, and its properties for different standardization periods are compared against oceanic El Niño–Southern Oscillation (ENSO) and other derived indices. In particular, we propose a modified TMI, hereinafter referred as TMI4, whose potential to identify the expected sign and the amount of future variations of rain induced by ENSO events in Colombia is analysed for selected extreme episodes. Results indicate that after the inclusion of sea level data, TMI4 can anticipate the development of El Niño events before the ENSO 3 and some other sea surface temperature-based regional indices, although its predictability depends on the ENSO type (canonical or Modoki). The explanation is that sea level includes new information into TMI4 on the onset of El Niño events. In particular, the signal of intraseasonal sea level anomalies carried by downwelling Kelvin waves is detected at Tumaco tide-gauge. Moreover, the analysis of the differences, both in magnitude and spatial distribution, of rainfall anomalies induced by positive (El Niño) and negative (La Niña) ENSO events characterized by TMI4 are regionally presented. As a result, we find that TMI4 is especially suited for extensive northern and western areas of mainland Colombia. For completeness, in the appendix we briefly introduce the semi-automated implementation of TMI4, including a visual interface, which is currently being tested by personnel within the operational oceanography area at Centro de Investigaciones Oceanográficas e Hidrográficas del Pacífico (Dimar-CCCP)., J. M. Sayol, L. M. Vásquez and J. L. Valencia thank funding from Centro de Investigaciones Oceanográficas e Hidrográficas del Pacífico – Dirección General Marítima de Colombia (Dimar), Ministry of National Defense of Colombia. J. M. Sayol also thanks the joint funding received from the Generalitat Valenciana and the European Social Fund under Grant APOSTD/2020/254. The work of DGG and IV was partially supported by Spanish Project RTI2018-093874-B-100 funded by MCIN/AEI/10.13039/501100011033 and by the Generalitat Valenciana Grant PROMETEO/2021/030. A. Orfila acknowledges financial support from FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación through MOCCA project (grant # RTI2018-093941-B-C31).

The spatial distribution, and the monthly and seasonal variability of mesoscale eddy observations derived from the AVISO eddy atlas are assessed in the Caribbean Sea during 1993–2019. The average lifetime for the whole set of eddies is 62 ± 37 days, mean amplitude of 7 ± 4 cm for cyclonic and 7 ± 4 cm for anticyclonic and mean radius of 100 ± 31 km for cyclonic and 108 ± 32 km for anticyclonic. Cyclonic eddies are on average more nonlinear than anticyclonic ones. The spatio-temporal variability in the number of eddy observations is evaluated against the Mean Eddy Kinetic Energy (MEKE) derived from geostrophic currents as well as from seasonal winds. Spatial distribution of eddy observations is correlated with MEKE while the migration of the intertropical convergence zone explains the advection of eddies towards the southern part of the basin., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. JMS received the joint funding from the Generalitat Valenciana and the European Social Fund under Grant APOSTD/2020/254. AO received financial support from projects Mocca and Lamarca (grants # RTI2018-093941-B-C31 and PID2021-123352OB-C31) funded by MCIN/AEI/ and by “ERDF A way of making Europe”, and from Fundación Iberostar and Université de Toulon-VAR. MELA is funded by Corporación CE-Marin through Convocatoria 14, 2018 supporting PhD candidates.

The computation of extreme waves near the coast is often complicated by the lack of extended time-series in shallow waters. As such, wave parameters related to long return periods are usually estimated starting from their offshore counterparts, either by i) computing return levels of wave parameters offshore and next propagating design waves toward the coast; or ii) downscaling the whole time-series of offshore data first, computing extreme waves at the coast at a second time. In this contribution, we comparatively apply the two methods at the Son Bou Beach in Menorca (Balearic Islands, West Mediterranean basin) to assess the uncertainty stemming from waves downscaling (that is, to perform the Extreme Value Analysis prior or after the propagation of waves to the shallow waters). Results show that the two approaches yield differences in the 100 years wave height as high as ≈1 m, suggesting the need to carefully account for this source of uncertainty in the preliminary design of coastal structures and coastal hazard assessment., FDL acknowledges financial support by the Ministero dell’Istruzione, dell’Università e della Ricerca, ISYPORT project. AO acknowledges financial support from FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación through MOCCA project (grant # RTI2018-093941-B-C31), Fundación Iberostar and Université de Toulon-VAR.

Every year the Caribbean Sea faces the passage of several tropical cyclones that generate coastal extreme sea levels with potential strong and hazardous impacts. In this work we simulate the storm surges and wind waves induced by a set of 1000 tropical cyclones over the Caribbean Sea that are representative of the present-day climate. These events have been extracted from a global database of synthetic tropical cyclones spanning a 10 000-year period. The atmospheric forcing fields, associated with the set of tropical cyclones, are used to feed a coupled hydrodynamic-wave model with high resolution (∼ 2 km) along the continental and island coasts. Given the large number of events modelled, our results allow detailed statistical analyses of the magnitude and mechanisms of coastal extreme sea levels, as well as the identification of one of the most exposed areas to both storm surges and extreme wind waves., Grant PID2021-124085OB-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,EU and grant RTI2018-093941-B-C31 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”., Peer reviewed

Mean sea-level rise (MSLR) will induce shoreline recession, increasing the stress on coastal systems of high socio-economic and environmental values. Localized mega-nourishments are meant to alleviate erosion problems by diffusing alongshore over decades and thus feeding adjacent beaches. The 21-st century morphological evolution of the Delfland coast, where the Sand Engine mega-nourishment was built in 2011, was simulated with the Q2Dmorfo model to assess the Sand Engine capacity to protect the area against the effects of MSLR. The calibrated and validated model was forced with historical wave and sea-level data and MSLR projections until 2100 corresponding to different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5). Results show that the Sand Engine diffusive trend will continue in forthcoming decades, with the feeding effect to adjacent beaches being less noticeable from 2050 onward. Superimposed to this alongshore diffusion, MSLR causes the shoreline to recede because of both passive-flooding and a net offshore sediment transport produced by wave reshaping and gravity. The existing feeding asymmetry enforces more sediment transport to the NE than to the SW, causing the former to remain stable whilst the SW shoreline retreats significantly, especially from 2050 onward. Sediment from the Sand Engine does not reach the beaches located more than 6 km to the SW, with a strong shoreline and profile recession in that area, as well as dune erosion. The uncertainties in the results are dominated by those related to the free model parameters up to 2050 whilst uncertainties in MSLR projections prevail from 2050 to 2100., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Grants RTI2018-093941-B-C33, RTI2018-093941-B-C31 and PID2021-124272OB-C22 funded by MCIN/AEI/10.13039/501100011033/ of the Spanish government and by “ERDF A way of making Europe”., Peer reviewed

Mean wave energy flux (hereinafter WEF) is assessed in the Caribbean Sea from a 60-year (1958–2017) wave hindcast. We use a novel approach, based on neural networks, to identify coherent regions of WEF and their association with different climate patterns. This method allows for a better evaluation of the underlying dynamics behind seasonal and inter-annual WEF variability, including the effect induced by the latitudinal migration of the Intertropical Convergence Zone (ITCZ) and the influence of El Niño-Southern Oscillation (ENSO) events. Results show regional differences in WEF variability likely due to both intensification and migration of the ITCZ. WEF exhibits a strong semi-seasonal signal in areas of the continental shelf, with maxima reached in January and June, in agreement with the known sea surface temperature and sea-level pressure variability patterns. At larger scales, WEF shows a significant correlation with the Oceanic Niño Index (ONI, which is the primary index for tracking the ocean part of ENSO climate pattern), depicting positive values in the central and western sides of the basin and negative ones at the eastern side., A. Orfila thanks financial support from grant RTI2018-093941-B-C31 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. A. Orejarena-Rondon was supported by COLCIENCIAS (Call 727) and POGO-SCORE Visiting fellowship at the Mediterranean Institute for Advanced Studies. Authors acknowledge DIMAR (Dirección General Maritima from Colombia) for the wave parameters supplied for the model validation. J.M. Sayol thanks the joint funding received from the Generalitat Valenciana and the European Social Fund under grant APOSTD/2020/254., Peer reviewed

14 pages, 12 figures, 3 tables.-- Data availability: The raw data supporting the conclusions of this article will be made available by the authors in the repository https://digital.csic.es/handle/10261/125458
(doi will be assigned after publication), The quantification of sediment exchanges between the beach and the lower shoreface, although being still poorly understood, is required to adequately forecast long-term coastal evolution. The effect of extreme storms on the morphodynamics of the nearshore and the sediment budget of the coastal zone seems to be strongly conditioned by local parameters, which should be incorporated into studies of medium- and long-term coastal evolution. In the upper shoreface, the dynamics of shore-parallel bars in sandy coasts have been extensively studied, but their implications for the sediment budget remain controversial as it is unclear whether their evolution simply represents a morphological change or denotes an escape of sediment from the upper shoreface. In order to provide new knowledge to address these questions, fifteen topo-bathymetric surveys that extend from the emerged beach to 15 m water depth were carried out along 1 km of Castelldefels beach (Llobregat Delta, Barcelona, western Mediterranean Sea) during the period 2011–2022. Morphological variations on the shoreface are studied, volumetric changes are estimated and implications on sedimentary exchanges in the littoral profile are inferred. The largest morphological (volumetric) changes are caused by cross-shore displacements of the nearshore bars, usually onshore during fair-weather conditions and offshore during storms. Volumetric changes suggest that shoreline retreat and the erosion of the shallow section of the profile during the last decade provides sediment to both the distal upper shoreface and the lower shoreface. The resulting sediment budget in the profile is almost zero in absence of extreme storms, but becomes highly negative when including extreme storms events that cause a net offshore transfer of sediment from the upper to the lower shoreface and, probably, the inner shelf. The characteristics of the study area (morphology, sediments, waves, tides) and in-situ hydrodynamic measurements at the lower shoreface suggest that the main potential onshore transport mechanisms (velocity and acceleration skewness during low-mid energy event) are small, making a significant transfer of sediment from the lower shoreface towards the shallow beach area unlikely at interannual scales. Thus, the study area is an example of low-lying coastal stretch in which the potential long-term shoreline retreat caused by sea level rise cannot be fully compensated by the sediment supplied from the lower shoreface. Other mechanisms, such as sediment supplied by longshore transport, are needed to counteract this trend, This work has been carried out in the framework of the MOCCA (RTI2018-093941-B-C2/C3), MOLLY (PID2021-124272OB-C21/C22), LAMARCA (PID2021-123352OB-C31), TECH2COAST (TED2021-130949B-I00) and SOLDEMOR (TED2021-130321B-I00) research projects funded by the Spanish Ministry of Science, Innovation and Universities – National Research Agency and EU “NextGenerationEU/PRTR. [...] This work is contributing to the ICM ‘Center of Excellence’ Severo Ochoa (CEX2019-000928-S), Peer reviewed

This paper presents an innovative methodology to assimilate peak period into wave models at a local scale. The proposed methodology estimates the peak period by processing time stack images from a video monitoring system for assimilation into a wave energy balance spectral model. Assimilation of the wave peak period is performed by correcting the boundary conditions and replacing the directional spectra prescribed by SWAN when using a nesting scheme. This methodology represents a new procedure for assimilating wave peak periods in coastal areas with video system infrastructures. The wave modelling is performed using a three-mesh nesting scheme where the finer domain coincides with the local scale and the proposed assimilation methodology is applied. The results show that the model improves the estimation of the peak period across the whole domain. The shape of the spectrum obtained changes significantly in the inner domain, mainly for low frequencies., AO gives thanks to grant RTI2018-093941-B-C31 funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”. The first author wants to thanks to Minciencias and its Scholarship program for doctoral excellence of the Bicentennial – first assignment and the Project ‘Programa estratégico para el Desarrollo de Tecnología Robótica Orientada a la Exploración Petrolera de los Fondos Marinos Colombianos’. Code:1210-531-30550., Peer reviewed

This paper describes a major update to the quasi-global, higher-frequency sea-level dataset known as GESLA (Global Extreme Sea Level Analysis). Versions 1 (released 2009) and 2 (released 2016) of the dataset have been used in many published studies, across a wide range of oceanographic and coastal engineering-related investigations concerned with evaluating tides, storm surges, extreme sea levels, and other related processes. The third version of the dataset (released 2021), presented here, contains double the number of years of data, and nearly four times the number of records, compared to Version 2. The dataset consists of records obtained from multiple sources around the world. This paper describes the assembly of the dataset, its processing, and its format, and outlines potential future improvements., We received no direct funding to assemble GESLA 3, however part of our time was funded on relevant grants, as follows: IDH time was partly funded via the NERC-funded CHANCE Project (NE/S010262/1); SAT was partly funded by the National Science Foundation (Award number 1455350 and 2013280); MM was supported by European Regional Development Fund/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación through the MOCCA project (grant no. RTI2018-093941-B-C31); PRT was supported by the National Oceanic and Atmospheric Administration Global Ocean Monitoring and Observation Program via the University of Hawaiʻi Sea Level Center (grant no. NA11NMF4320128)., Peer reviewed

A set of historical tide gauge sea-level records from two locations in Santander (Northern Spain) and Alicante (Spanish Mediterranean coast) have been recovered from logbooks stored in national archives. Sea-level measurements have been digitized, quality-controlled and merged into three consistent sea-level time series (two in Alicante and one in Santander) using high-precision levelling information. The historical sea-level record in Santander consists of a daily time series spanning the period 1876-1924 and it is further connected to the record from the modern tide gauge station nearby, ensuring datum continuity up to the present. The sea-level recording in Alicante started in 1870, with daily averaged values until the 1920s and hourly afterwards, and the tide gauges at the two Alicante sites are still operating, thereby providing one of the longest tide gauge sea-level time series in the Mediterranean Sea. The long-term consistency and reliability of the new records are discussed based on comparison with nearby tide gauge time series., The research presented in this paper was partially funded by the Spanish Ministry of Science, Innovation and Universities (MOCCA, project number RTI2018-093941-B-C31) (M.M., A.A.) and the National Science Foundation CAREER award number 1455350 (S.T.)., Peer reviewed

Se realizaron 14 campañas topo-batimétricas desde la playa emergida hasta los 15 m
de profundidad, a lo largo de 1 km en la playa de Castelldefels (Delta del Llobregat,
Barcelona) durante el periodo 2011-2020. Se analizan las variaciones morfológicas que tienen
lugar, los cambios volumétricos y sus posibles implicaciones en los intercambios sedimentarios
en el perfil litoral. Los principales cambios morfológicos están causados por los
desplazamientos transversales de las barras de arena, generalmente hacia tierra durante
condiciones de buen tiempo y hacia mayor profundidad durante las tormentas más fuertes. Los
cambios volumétricos sugieren que el retroceso de la línea de costa durante la última década
aporta sedimento a la parte superior de la playa sumergida, mientras que los eventos más
extremos producen una transferencia de sedimento hacia la plataforma continental, que
podrían ser parcialmente irrecuperables para la dinámica litoral. El balance sedimentario
resultante es negativo

Mean sea-level rise (MSLR) will induce shoreline recession, increasing the stress on coastal systems of high socio-economic and environmental values. Localized mega-nourishments are meant to alleviate erosion problems by diffusing alongshore over decades and thus feeding adjacent beaches. The 21-st century morphological evolution of the Delfland coast, where the Sand Engine mega-nourishment was built in 2011, was simulated with the Q2Dmorfo model to assess the Sand Engine capacity to protect the area against the effects of MSLR. The calibrated and validated model was forced with historical wave and sea-level data and MSLR projections until 2100 corresponding to different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5). Results show that the Sand Engine diffusive trend will continue in forthcoming decades, with the feeding effect to adjacent beaches being less noticeable from 2050 onward. Superimposed to this alongshore diffusion, MSLR causes the shoreline to recede because of both passive-flooding and a net offshore sediment transport produced by wave reshaping and gravity. The existing feeding asymmetry enforces more sediment transport to the NE than to the SW, causing the former to remain stable whilst the SW shoreline retreats significantly, especially from 2050 onward. Sediment from the Sand Engine does not reach the beaches located more than 6 km to the SW, with a strong shoreline and profile recession in that area, as well as dune erosion. The uncertainties in the results are dominated by those related to the free model parameters up to 2050 whilst uncertainties in MSLR projections prevail from 2050 to 2100., This work has been funded by the Spanish government through the research projects RTI2018-093941-B-C31 and RTI2018-093941-B-C33 (MINECO/FEDER), Peer Reviewed

The quantification of sediment exchanges between the beach and the lower shoreface, although being still poorly understood, is required to adequately forecast long-term coastal evolution. The effect of extreme storms on the morphodynamics of the nearshore and the sediment budget of the coastal zone seems to be strongly conditioned by local parameters, which should be incorporated into studies of medium- and long-term coastal evolution. In the upper shoreface, the dynamics of shore-parallel bars in sandy coasts have been extensively studied, but their implications for the sediment budget remain controversial as it is unclear whether their evolution simply represents a morphological change or denotes an escape of sediment from the upper shoreface. In order to provide new knowledge to address these questions, fifteen topo-bathymetric surveys that extend from the emerged beach to 15 m water depth were carried out along 1 km of Castelldefels beach (Llobregat Delta, Barcelona, western Mediterranean Sea) during the period 2011–2022. Morphological variations on the shoreface are studied, volumetric changes are estimated and implications on sedimentary exchanges in the littoral profile are inferred. The largest morphological (volumetric) changes are caused by cross-shore displacements of the nearshore bars, usually onshore during fair-weather conditions and offshore during storms. Volumetric changes suggest that shoreline retreat and the erosion of the shallow section of the profile during the last decade provides sediment to both the distal upper shoreface and the lower shoreface. The resulting sediment budget in the profile is almost zero in absence of extreme storms, but becomes highly negative when including extreme storms events that cause a net offshore transfer of sediment from the upper to the lower shoreface and, probably, the inner shelf. The characteristics of the study area (morphology, sediments, waves, tides) and in-situ hydrodynamic measurements at the lower shoreface suggest that the main potential onshore transport mechanisms (velocity and acceleration skewness during low-mid energy event) are small, making a significant transfer of sediment from the lower shoreface towards the shallow beach area unlikely at interannual scales. Thus, the study area is an example of low-lying coastal stretch in which the potential long-term shoreline retreat caused by sea level rise cannot be fully compensated by the sediment supplied from the lower shoreface. Other mechanisms, such as sediment supplied by longshore transport, are needed to counteract this trend., This work has been carried out in the framework of the MOCCA (RTI2018-093941-B-C2/C3), MOLLY (PID2021-124272OB-C21/C22), LAMARCA (PID2021-123352OB-C31), TECH2COAST (TED2021- 130949B-I00) and SOLDEMOR (TED2021-130321B-I00) research pro- jects funded by the Spanish Ministry of Science, Innovation and Uni- versities – National Research Agency and EU “NextGenerationEU/PRTR. Puertos del Estado provides the wave data and the Port of Barcelona provides the bathymetric data of July 2020. This work is contributing to the ICM ‘Center of Excellence’ Severo Ochoa (CEX2019-000928-S)., Peer Reviewed