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Sea extreme events affect the integrity and operation of the offshore structures, then, it is important to analyze wind-waves-currents loads over the structural dynamics. Traditional offshore designing identifies structural parameters with certain limitations: physical modeling involves using shaking tables in dry conditions; numerical simulations have not sufficiently considered the effects of combined extreme waves-wind-current loads over the structure and the significance of the near and far hydrodynamic field over the structure. The non-linear interactions in the near hydrodynamic field generate viscous damping that modifies the dynamic structural parameters of the offshore structures. The traditional determination of structural parameters considers the hydrodynamic forces computed from wave records, omitting fluid-structure interactions that could generate unexpected damped periods and amplification peaks. This study applied physical modeling to determine floating structural parameters, considering combined loads and the effect of far and near hydrodynamic field in the fluid-structure interaction. The calculated transfer functions in the near hydrodynamic field revealed the highest amplification of the structural accelerations, and the transfer functions in the far field did not evidence structural resonance. Finally, this study recommends measuring the near hydrodynamic field and applying DOE-ANOVA for offshore designing to assess the viscous damping that may provoke dangerous structural amplifications.

Deep ocean water (DOW) is a renewable alternative to the many sustainability challenges that the Caribbean faces today. DOW can provide seawater air conditioning (SWAC) for buildings and greenhouses, provide electricity through an ocean thermal energy conversion plant (OTEC), and provide nutrients for aquaculture and cosmetic industries. However, today the implementation of DOW technologies in the Caribbean is inexistent, and studies about DOW potential in the Caribbean are limited. We present a methodology for estimating the practical potential of a city while considering constraints in ocean currents, temperature, and salinity. We applied the methodology to five cities in the Caribbean and found that the average potential is about 50 m3/s per city, enough to supply more than 100% of a city’s demand for air conditioning and 60% of its demand for electricity. We also estimated the monthly availability of DOW resource, with maximum extraction potentials between December to March, and minimum values between August to October. These estimations serve as input for future feasibility and design studies on DOW technologies in the Caribbean. Given the assumptions, the found potential may be underestimated; thus, the results of this study can be considered as a minimum reference value, complementary to the maximum theoretical potential found in previous studies.

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.

This paper addresses the current status and future research and development perspectives associated with technologies to harness offshore renewable energy, including offshore wind, waves, tides, ocean currents, and thermal and salinity gradient, in South America (SA). It focuses on five countries: Argentina, Brazil, Chile, Colombia and Uruguay. At first, a comprehensive survey presents the number of scientific papers classified based on the resource to show the tendency and importance of such subjects in the academic community. Each country’s electricity matrix and grid connection are shown to understand the region’s renewable source participation situation. The potential of offshore renewable resources is addressed by considering the published technical papers in scientific journals. The main conflicts and synergies associated with ocean space utilization are presented by considering the exclusive economic zone of each country. The status of the regulatory frameworks to promote and development of offshore renewable energies is presented. Two sections are dedicated to presenting the active, decommissioned and planned projects, research groups and laboratory infrastructures to develop the technologies. The last section discusses the future perspectives on the development of this sector in SA. It is observed that SA, with more than 25,000 km of coastline, has a great potential for offshore renewable energy; however, so far, these resources have not been explored commercially. Larger investment in the sector, establishing an adequate legal framework and deploying full-scale demonstration projects at sea are necessary for the commercialization of such technologies in SA.

In this work, the backward wave breaking process by the presence of flow separation vortices under a solitary wave is studied. Based on a set of non-dimensional variables defined from the Buckingham Π theorem, a set of numerical experiments are performed in order to analyze the effect of varying the submerged obstacle geometry on the surrounding flow and free surface by using a RANS-VOF model. Model simulations are tested against available experiments showing a good performance of numerical results. The structure-submergence ratio and the structure-based Reynolds number modulate the type of breaking (collapsing-plunging). The structure aspect ratio defines the location and number of backward breaking points for rectangular structures and the breaking wave direction for triangular structures (either forward or backward). Moreover, when the flow separation vortex diameter is comparable to the local water depth a backward wave breaking process is originated. The vortex behaves as a rigid body that accelerates the flow at the upper side of the vortex, accumulating mass at the downstream side where a very large slope on the free surface makes the water fall backward due to gravity., A. Cáceres-Euse wants to thank COLCIENCIAS for the scholarship #647. A. Orfila thanks financial support from LAMARCA Project (PID2021-123352OB-C31) funded by MCIN/AEI/ and by “ERDF A way of making Europe”. I. Hernández-Carrasco is supported by the TRITOP Project (UIB2021-PD06) funded by the Universidad de las Islas Baleares – FEDER (UE) . M. Wyssmann thanks support by the Chancellor’s Fellowship awarded by the University of Tennessee at Knoxville

The swash zone is the most dynamic part of the upper beach. Here breaking waves interact with sediments, leading to beach morphodynamics, and eventually to coastal erosion and flooding. An understanding of swash characteristics such as the vertical excursion and mean swash period is of vital importance to identify and predict the possible impact of storms in coastal areas. The prediction of these swash parameters is commonly based on bulk offshore spectral wave parameters and the beach slope, the latter being expensive to monitor. In this study, a dataset from an intermediate beach on the south-west coast of Sylt, Germany was derived to analyze swash characteristics. Field observations show high variability in swash excursion even for similar incident wave conditions if expressed by bulk parameters. Here, the role of frequency spread was further investigated. An inverse relationship between swash frequency spread and swash characteristics (excursion and mean period) was identified. A parameterization for the swash frequency spread based on incident wave parameters is proposed, and a new approach to obtain total swash excursion and mean swash period is developed. The parameterization is validated using two independent swash datasets (Duck 1982 and Duck 1994) and compared to the predictive ability of other parameterizations. It is highlighted that common parameterizations based on peak period do not perform well in characterizing incident conditions when bi-modal spectra are present. The choice of the right descriptor for wave periods may have a more pronounced influence on the predictive skill than the inclusion of the beach slope.

River mouths are locations with high theoretical potential for harvesting salinity gradient energy (SGE) since waters of different salinities are abundant in these places. However, the net extractable SGE potential—or site-specific potential (SSP)—is determined not only by the available natural resources but also by the energy consumption required for operating the power plant. Particularly, the required inputs for water pretreatment prior to energy generation to preserve the proper functioning of the membranes and other components within the systems, have been identified as a major drawback for SGE generation from natural waters. In this paper, the required energy consumed during water pretreatment was estimated, comparing conventional and membrane-based methods. This energy input was included in the formulations of the SSP, as a function of the design flow of the power plant and was used to assess the extractable SGE potential at the Magdalena River mouth, a top-ten system for SGE generation worldwide. The results showed that water pretreatment produced an important reduction of the SSP in the case study, while high potentials were still found for appropriate design flows.

Some branched corals are capable of surviving in wave/current exposed areas with moderate to high energy environments, where their branches, their geometry and the global and rigid structure of their colonies play an important role for wave damping due to bottom friction and wave energy dissipation due to turbulence. Constant frictional coefficients are commonly used within wave propagation models to consider reef roughness but without accounting for the type of coral species, its topological characteristics, form and distribution over the reef surface. In this sense, this study aims to improve the understanding of near-bed hydrodynamics in coral reefs by examining the drag and inertia coefficients of branched coral colonies of Acropora palmata. Laboratory tests were carried out considering steady and oscillatory flow conditions. In-line forces, flow velocities and water surface elevations over 3-D models of Acropora palmata were recorded for both a single coral colony and a group of corals. Additionally, the validated open source CFD (Computational Fluid Dynamics) toolbox OpenFOAM® was used to simulate the hydrodynamic performance over the coral structures for a wide range of wave heights and periods. The results show that under steady flow conditions, the drag coefficient ( C D ) can be well represented as a function of the Reynolds number (Re) by means of a power law equation as C D = aRe b +c. Also, under oscillatory flow conditions, it was found that the inertia force ( F M ) dominates over the drag component ( F D ), explaining more than 84% of the total force exerted on the coral structure. Prediction formulas were developed and validated with the laboratory test to predict the resistance coefficients (drag and inertia) as function of Keulegan and Carpenter number (KC) for the C D (R 2 = 0 .89) and C M (R 2 = 0 .92). The CFD modeling showed to be an alternative for the modeling of the hydrodynamic forces exerted over complex coral shapes and to analyze the fluid–structure interaction around natural structures.

Reefs are known to provide coastal protection and important ecosystem services for many coastlines around the world. Physical processes such as wave damping, sediment transport and nearshore hydrodynamics are closely related to the coastal protection services provided by reefs. The steep-fronted bathymetries of reefs cause abrupt wave transformations and wave damping alongshore, while reef roughness has an important contribution to coastal protection. Five Latin-American case studies are presented to illustrate the coastal protection offered by reefs and their contribution to wave damping. The methodologies applied (e.g. numerical modelling, field measurements) and reef conditions (e.g. reef degradation scenarios and contribution of reef roughness) are listed. Considerable efforts have been made towards diagnosing, understanding and modelling the hydrodynamic transformations induced by reefs. Based on physical and field surveys, roughness and friction parameters were derived in order to implement calibrated and validated numerical models. Discussion on the advantages and disadvantages of the different models applied in the study cases is provided as well as on the needs of highlighting physical processes and the analysis of reef hydrodynamics for supporting appropriate ecosystem-based management.

Tropical countries have island and continental ecosystems of great value for tourism, fisheries and also for their conservation development potential. These natural habitats, including among other beaches, seagrass beds, mangrove forests and coral reefs can dissipate wave energy acting as barriers against high waves and high water levels to eventually protect coastal infrastructure and communities. However, in recent decades, they have been subject to strong anthropic pressure and extreme events due to natural causes as well as to climate change. Therefore, the global trend is to understand the eco-systemic services that these natural environments can provide and their economic value in terms of reducing damages caused by coastal erosion and flooding. A methodological framework is presented in order to quantify the impact of natural ecosystems in coastal protection and their environmental assessment based on numerical models available in the literature. In addition to the methodology, a study of a typical Caribbean fringing coral reef and its response to different sea level rise and extreme events scenarios was conducted. The contribution of these efforts from a technological and scientific point of view, lies in the integration of different disciplines required to combine the physical properties of hydrodynamic studies with biological factors as an input to provide practical socio-economic and environmental solutions in those regions in which these ecosystems predominate. Furthermore, a numerical modeling tool to study wave energy dissipation, focusing the analysis on the impact of natural ecosystems (coral reefs) on coastal erosion and flooding was implemented. This information will help coastal managers and decision-makers understand the coastal protection services provided by nearshore habitats in order to improve and design new coastal development strategies under global change scenarios.

Coastal ecosystems like coral barrier reefs and mangrove forests have been designated as environments in need of protection. This is not only because they are threatened by climate change, but also because of the important role they play in coastal protection. Some field studies based on Rhizophora mangrove trees have analyzed the force induced by water flow over their roots and the wave dissipation capacity of these trees under tidal regimes and sea waves. Various methods have been used to calculate energy dissipation in the past, but these do not include the drag coefficient (CD) with field data calibration. The study presented here was conducted to investigate the capacity of a small natural Rhizophora mangrove patch (at experimental scale) located on Isla Grande in the Colombian Caribbean Sea to mitigate wave energy. The total energy dissipation, including the slope bottom and the effects of vegetation, was calculated. Parametric equations were used to calculate the effects of vegetation. The drag force (FD) was computed using Morrison’s equation and the CD was calculated using Mazda’s method. The results show a mean energy dissipation difference of 9.6% between the energy balance and dissipation coefficients where the CD was calculated for each sea state. The dissipation coefficients were calculated with constant CD values (0.06, 3.48 and 6.90). None of the three cases could explain the 90.4% energy flux, as in the case of vegetation dissipation (Dveg) with calculated and non-constant CD values. Despite the small size of the mangrove patch, the results show an increase in the CD (with values of up to 7.9) as a result of lower values of the Reynolds number (Re) (about 7.3 × 105). This demonstrates experimentally the role that even a small patch of mangrove vegetation plays in attenuating sea waves (as CD is a function of sea states), and higher magnitudes were obtained than those recorded in the literature using other vegetation types. A nonlinear contribution to energy flow by bottom dissipation and vegetation dissipation was observed. Our results highlight the need to scale measurements up to forest level in order to accurately quantify the impact of mangrove vegetation on wave attenuation and determine the possible impact on the protection of coastal ecosystems and infrastructure.

A shear layer at the top of a submerged canopy was analyzed under oscillatory flow driven by free surface waves. By applying a dimensional analysis at the shear layer scale, a simple analyt...

Long wave-structure interaction is studied numerically. The Rayleigh and Goring wave generation theories with a solitary wave with two nonlinearity factors and three discretization schemes for the advective terms for the wave propagation are evaluated. Results show good agreement for the main wave peak and for the wave decay rate. The model captures the trailing waves and some differences on the wave decay rates are observed. Majorcatic and solitary wave cases passing over submerged structure is then studied. For the monochromatic scenario, the model agrees very well with the free surface experimental data, and a ”Linear fluid structure interaction mechanism” can be observed based on the structure geometry and the absence of adverse pressure gradient in the flow. For the solitary wave case interacting with a slender column, the numerical model agrees very well with the measurements, showing that an adverse pressure gradient in the flow is presented and the vortex in the flow induces a wave breaking process, not by the bottom friction, nor by water depth reduction but by a strong transport of mass from upstream to downstream side of the vortex; this turbulent structure is the dominant process, even when the wave breaking is present.

The understanding of physical processes over submerged reefs represents an important ongoing research topic when considering wave energy dissipation and coastal protection that these environments provide. Detailed analyses are required to assess wave damping based on the contribution of reef roughness and wave breaking. For this purpose, the CFD (computational fluid dynamics) toolbox OpenFOAM® is applied to simulate the wave energy dissipation process over reefs with explicit accounting for the complexities of coral shape instead of commonly applied parameterized approaches for bottom roughness and wave breaking. Model validation was performed through comparison with field measurements over a reef profile of Tesoro Island in the Colombian Caribbean. Quantitative analysis of wave damping caused by wave breaking and reef roughness was conducted for (1) moderate and extreme wave conditions, (2) smooth and rough seabed configurations and (3) changes in the water depth over the reef crest. Wave height attenuation is found to vary along the reef profile reaching differences of up to 55% between smooth and rough reef surface scenarios, particularly for moderate wave conditions. Wave breaking, high turbulent flows and detachment of undertow currents are among the reef roughness effects on hydrodynamics. The fore-reef terrace and the reef crest are identified as the most critical zones where dissipation takes place. Wave breaking from rough seabeds provides a global wave attenuation of 75.4–94.8%, with the reef roughness alone accounting for ~ 4–14%. Under extreme wave height scenarios, the wave damping from reef roughness is not significant. Further predictions regarding roughness effects on the reef hydrodynamics, wave set-up and undertow currents for moderate and extreme wave climate conditions are also shown. Directions for future research using CFD are presented to address limitations that arise from the limited span-wise domain in our approach that prevents development of large lateral coherent structures.

During recent decades there has been open debate about a possible increase in the number and magnitude of more energetic hurricanes in the Atlantic, including their causes and implications. In this work, changes in extreme wave heights induced by hurricanes in the Caribbean Sea are analyzed. A non-stationary model is employed to study possible changes in the frequency of occurrence and magnitude of extreme waves from an hourly time series during the period of 1979–2012. The results indicate an increase in the occurrence of extreme wave events in the eastern and central Caribbean, and consequently, a positive long-term trend for 30yr return values. The zone of the highest trends is observed in the western basin in the middle of the Caribbean Sea towards the Gulf of Mexico. A final rate of approximately 2 events/year for 2012 is found throughout the Yucatan basin.

Pelaez-Zapata, D.S.; Montoya, R.D., and Osorio, A.F., 2018. Numerical study of run-up oscillations over fringing reefs. This work presents a numerical study of run-up oscillations over a typical fringing reef profile at the laboratory scale. The nonhydrostatic SWASH model was calibrated and validated using experimental data of free surface elevation for eight gauges and run-up oscillations. The model shows a high sensitivity to variations in the parameters of bottom friction and horizontal mixing length. A process of calibration found the optimal values to be 0.014 s m−1/3 and 0.01 m, respectively. With these values, the model is good at reproducing bulk run-up parameters such as the mean run-up period (r2 = 0.93), sea-swell significant run-up (r2 = 0.93), and infragravity significant run-up (r2 = 0.88). The ratio between the infragravity and sea-swell run-up is highly dependent on the surf similarity parameter. For dissipative and intermediate conditions, the run-up is mainly dominated by low-fr...

Flooding episodes occur frequently in the Colombian Caribbean and cause damage to coastal settlements. However, there is little knowledge about these episodes and about how changes in associated variables affect coastal flooding. This paper presents the results obtained from analyzing the temporal variability of flood levels in Monitos-Cordoba on the Colombian Caribbean coast, as well as the contribution their components make to different time scales. To achieve this, the total sea level (TSL) was estimated indirectly as the sum of the variables involved (sea level anomalies, astronomical tide, storm surge and wave runup). These variables were obtained by applying numerical and empirical modeling using satellite altimetry data, tidal modeled data and wind, waves and atmospheric pressure from reanalysis. Data Trends and contributions were analyzed using statistical methods, including variance analysis, exceedance distributions, linear regressions, Sen-Slope and the Mann Kendall test. The results indicate that the total sea level has a semi-annual cycle with its highest maximum levels in the months of December to March and its lowest maximum levels in the months of April and September. The total sea level variability in Monitos is dominated by the runup component at monthly, intra-annual and inter-annual scales, while at longer-term timescales (2–7 years and greater) variability is dominated by the sea level anomaly. Runup is the greatest contributor to the total sea level, followed by the sea level anomaly in average conditions and the astronomical tide in extreme conditions. There was a trend of increasing total sea level, related to the trend in sea level anomaly, with a consequent increasing trend of frequency and magnitude of extreme sea levels.

Conde-Frias, M.; Otero, L.; Restrepo, J.C.; Ortiz, J.C.; Ruiz, J., and Osorio, A.F., 2017. Swash oscillations in a microtidal dissipative beach. This paper evaluates the relationship between gravity and infragravity energy with swash oscillations as well as the model's ability to reproduce the transformation of the wave as it approaches the shore on a dissipative beach. For this purpose, numerical experiments were conducted in a dissipative beach from Cartagena, Colombia. Mean free surface measurements were carried out for 2 days in February 2014 by installing a cross-shore array of pressure sensors, as well as a Fourier analysis from these measurements to identify frequency components that characterize the waves and the energy associated with them. To implement the numerical modelling, the SWASH model (The Simulation WAves till Shore is a numerical model that resolves nonlinear shallow-water equations) was set up by using the bathymetric profile of Bocagrande Beach obtained during the field camp...

This paper aims to highlight the prevailing experiences of Latin America and to clarify what ‘green infrastructure’ entails in addition to describing seven case studies from a range of coastal ecosystems (wetlands, coastal dunes, beaches and coral reefs) at scales varying from local to regional. The case studies are categorised according to their degree of naturalness (nature-based, engineered ecosystems, soft engineering, ecologically enhanced hard infrastructure and de-engineering). Generally, the implementation of green infrastructure projects aims to increase resilience, enhance the provision of ecosystem services, recover biodiversity, reduce the negative effects of hard infrastructure and implement corrective measures. The greatest benefits of these projects relate to the creation of multi-functional spaces, which often combine the above advantages with improved opportunities for recreation and/or economic activities. It is hoped that this paper will disseminate the experience in green infrastructure among academics and practitioners and stimulate wider adoption of green infrastructure projects and good practices.

This paper evaluates the implementation of salinity gradient power (SGP) based on reverse electrodialysis (RED) in the Caribbean region of Colombia, specifically at the Magdalena River mouth (MRM). Our multidisciplinary approach comprises technical, technological, and technology diffusion assessments (market analysis). We estimate the theoretical energy potential in the MRM from spatial and temporal measurements of the physical and biochemical properties of the waters. Thereafter, we compare the power output of a tailored RED prototype using synthetic solutions and untreated natural waters from MRM. Finally, we propose a dynamic model for RED diffusion in Colombia. Our results show that the MRM exhibits suitable conditions for harnessing SGP given the prevailing thermohaline structure, tolerable water quality, and an existing physical barrier between the sea and the river. However, our experiments demonstrated that maximum power is reduced by half when feeding with MRM waters. This is attributed to the divalent ions and low concentration of the river. Finally, the dynamic model shows that the learning rate and the initial operational costs are key variables for technology diffusion. This research is a pioneer in integrating multidisciplinary perspectives of SGP in emerging economies. However, this baseline may be further complemented with socio-political, and economic analyses.

Accurate and efficient measurement of fluid velocities in several kind of experiments, has been acquiring high relevance, for several kind of applications. Particle Image Velocimetry is a noninvasive technique which also provides velocity estimates in several points of the measuring region. Regarding the PIV computations, high resolution of the digital input images, may lead to poor performance. There are also many error sources, regarding the PIV setup itself. This paper describes a method aimed both to speeding up the PIV computations, and minimizing the divergences (noise) present in the output velocity fields. The obtained results are promising, obtaining a speedup of up to 55 % , with respect to the traditional cross correlation based method, with a comparable precision.

Salinity gradient energy (SGE) is a clean and renewable energy source that can be harnessed from the controlled mixing of two water masses of different salt concentration. Various natural and artificial systems offer conditions under which SGE can be harnessed amongst which river mouths play the prominent role in a global assessment. The theoretical SGE potential at river mouths has been previously estimated to be 15,102 TWh/a, equivalent to 74% of the worldwide electricity consumption; however, practical extractable SGE from these systems depends on several physical and environmental constraints that are discussed here. The suitability, sustainability and reliability of the exploitation of this renewable energy are considered based on quantified descriptors. It is shown that practically 625 TWh/a of SGE are globally extractable from river mouths, equivalent to 3% of global electricity consumption. Although this is much smaller than the theoretical potential, is still a significant amount of clean energy.

In this paper, we estimate the potential marine energy available from different types of resources in Colombia: waves, tides, currents, salinity gradients and thermal gradients, focussing on specific locations. The main constraint on this analysis is the lack of long-term marine instrumentation and data. In order to overcome this difficulty, we use oceanic numerical modelling with data from reanalysis models, climatic data from remote sensors, and primary data from existing instrumentation and fieldwork. The models were calibrated and run to calculate—based on existing marine systems—the potential nationwide marine power resources, on different time and spatial scales, for both the Colombian Caribbean and Pacific coasts. For each marine resource, we first explain the method used to assess the power potential; then we present the potential marine energy result. Further, we carry out a policy analysis where we discuss not only the power potential but also the barriers (mainly cost) faced by marine energy. Given the potentials found by earlier studies, these results define for Colombia, and also for Central and South America generally, the road map for future pre-feasibility analysis, taking into account the energy demands of the populations, existing technologies, and the environmental, social and geographical characteristics of the regions.

Wave dissipation by drag forces is considered the dominant wave transformation process in fringe mangroves even though other process may be present. Furthermore, mangrove loss generates vertical erosion and changes in the nearshore profile that can affect wave breaking, whereas changes in vegetation density owing to species composition or disturbances may affect drag dissipation. The aim of this study is to identify local and global geographical control factors of wave attenuation in mangrove environments and to assess the effect of nearshore profile modifications by mangrove loss on wave breaking dissipation. Bottom wave attenuation from breaking and shoaling, the total wave energy attenuation rate, and wave reflection were estimated using modeling, pressure sensors, and reflection coefficients, respectively, at sites with contrasting wave power, bathymetric slope changes, vegetation density, and logging disturbance. Wave breaking changes by mangrove loss were estimated using wave evolution modeling under three successive slope increments by 0.7% in two background mangrove nearshore profiles. The wave energy attenuation rate at the study sites was affected by incident wave height (28–76%), epiphytic oyster presence, vegetation density, tidal inundation (41–55%), and wave reflection from cliffs. The last two variables explained the wave attenuation rate variability at a cliffed study site (61–70%), whereas the last three variables explained the wave attenuation rate variability on a global scale (92%). Wave attenuation rates by vegetation and bottom friction were underestimated (2–59% from global scale data) when wave shoaling was not considered. The wave energy increased or moved further inland in unvegetated scenarios in comparison with vegetated shores. In addition to drag forces, mangroves can promote wave attenuation by inducing friction, wave breaking, and wave reflection from prop-roots epiphytic organisms, shallow nearshore profiles, and cliffed edges, respectively.

A new approach to estimate the peak period using time stack images from a video monitoring system is presented. The method is an improvement of the one developed by Stockdon and Holman (Stockdon, H.F., Holman, R.A., 2000. Estimation of wave phase speed and nearshore bathymetry from video imagery. J. Geophys. Res. Ocean. 105, 22015–22033), (S&H) including thresholding of the image to automatically identify free foam zone in the image, improved filtering procedure and windowing of the pixel intensity series in order to avoid noisy signals and spectral leakage. Results are tested against measurements in four beaches showing an absolute error below 2 s for 75% of the analyzed images despite the variable light conditions and noisy signals. Comparison with the S&H method is given showing that the new method reduces relative error on average by 28%. These results are achieved without taking into account the camera configuration requiring only the identification of a representative amount of land pixels in order to adequately eliminate noisy signals produced by environmental light fluctuations., Authors acknowledge financial support from Convocatoria Nacional de proyectos para el fortalecimiento de la investigación, creación e innovación de la Universidad Nacional de Colombia through project “Analysis of the hydrodynamic and morphodynamic characteristics of a sandy beach by means of numerical modeling and image processing” and “Estrategia de transformación del sector energético Colombiano en el horizonte de 2030″ supported by Colciencias Ecosistema Científico Contract FP44842-210-2018, as well as from the Spanish MINECO/FEDER through project MUSA(CTM-2015-66225-C2-2-P). The authors also wish to express thanks to the OCEANICOS, MARUM, IMEDEA and SOCIB research groups for the data used in this work. Data from the HZG COSYNA “Bunkerhill” wave buoy was obtained from the open COSYNA data portal. This work was partially performed while A. Orfila was a visiting scientist at the Earth, Environmental and Planetary Science Department at Brown University through a Ministerio de Ciencia, Innovacion y Universidades fellowship (PRX18/00218).

13 pages, 10 figures, 2 tables.-- All data are accessible from http://apps.socib.es/beamon/ (Beach monitoring facility, 2018) and http://thredds.socib.es/thredds/catalog/mooring/waves_recorder/mobims_playadepalma/L1/2014/catalog.html (SOCIB Data centre, 2018), The morphodynamic response of a microtidal beach under a storm group is analyzed, and the effects of each individual event are inferred from a numerical model, in situ measurements and video imaging. The combination of these approaches represents a multiplatform tool for beach management, especially during adverse conditions. Here, the morphodynamic response is examined during a period with a group of three storms. The first storm, with moderate conditions (H ∼ 1m during 6 h), eroded the aerial beach and generated a submerged sandbar in the breaking zone. The bar was further directed offshore during the more energetic second event (H = 3.5m and 53 h). The third storm, similar to the first one, hardly affected the beach morphology, which stresses the importance of the beach configuration previous to a storm. The volume of sand mobilized during the storm group is around 17.65mm. During the following months, which are characterized by mild wave conditions, the aerial beach recovered half of the volume of sand that is transported offshore during the storm group (∼ 9.27mm). The analysis of beach evolution shows two different characteristic timescales for the erosion and recovery processes associated with the storm and mild conditions, respectively. In addition, the response depends largely on the previous beach morphological state. The work also stresses the importance of using different tools (video monitoring, modeling, and field campaign) to analyze beach morphodynamics, Authors acknowledge financial support from MINECO/FEDER through projects MORFINTRA/MUSA (CTM2015-66225-C2-2-P) and CLIMPACT (CGL2014-54246-C2-1-R). Verónica Morales-Márquez is supported by an FPI grant from the Ministerio de Economía, Industria y Competitividad of the Spanish government associated with MORFINTRA/MUSA. Daniel Conti is supported by a PhD fellowship (FPI/1543/2013) granted by the Conselleria d'Educació, Cultura i Universitats from the Government of the Balearic Islands co-financed by the European Social Fund

The theoretical potential of salinity gradient energy in river mouth systems is the maximum amount of energy that can be extracted from the controlled mixing of river water and seawater. It is calculated using the Gibbs free energy of mixing equations considering as inputs the mean rivers' discharge and the long term salinity of the ocean basin. However, this theoretical amount of energy can be far from the reality because both, the river discharge and the salinity of the ocean, have natural variations in different time scales. In this paper we expose the site constraints related with the variability of the salinity gradients that must be considered in order to make a more accurate estimation of the available resources and calculate the so-called site specific potential for the most important and feasible river mouths of Colombia. The results show that in Colombia a mean site specific potential of 15.6 GW can be achieved, mainly in the Magdalena River mouth (97% of total). But more important, the results show that the salinity structure of the studied systems have different responses to variations of the environmental forcing, despite being located in the same ocean basin, and therefore, the energy potential for each river mouth has different variability patterns at different time scales. Decreases of the estimated energy potential up to 69% were found when the site specific potential is calculated instead of the theoretical potential. This prove that more detailed input data than long term discharges and salinities are necessary in order to make accurate estimations of local and regional salinity gradient energy potentials.

Sandbars are natural features generated in the nearshore zones by the interaction between the sea and the coast. The short-term processes that drive sandbar behavior are waves and sediment transport. The interaction between waves and the coast is highly nonlinear and, traditionally, process-based models (e.g., evolution models) have been used for modelling and analyzing sandbar behavior in the short term. However, medium- to long-term predictions are not always possible with these models due to their exponential error accumulation. Data-driven models emerge as an alternative to process-based models as they do not need insight on the physical knowledge of the model, but they extract knowledge from patterns found in the data. In this paper, we apply the data-driven techniques: EMD (empirical mode decomposition) method and ARNN (autoregressive neural networks) on sandbar and wave time series from the coast of Cartagena de Indias, Colombia. The former is used for analyzing the relationship between sandbar and wave conditions in a graphical way; and the latter is used for deriving nonlinear simple/partial cross/auto-correlation coefficients. Evidence of nonlinear dependencies is detected between the present state of sandbar location and the past states of wave conditions. HighlightsData-driven techniques were used to analyze sandbar data.Neural networks helped to detect nonlinear relations between sandbar and waves.It was found that sandbar behavior has memory.Empirical mode decomposition helps to visualize complex sandbar behavior.Memory and external waves produce an elastic effect in sandbar movement.

The response of a rocky beach to different possible combinations of hydrodynamic conditions (tides, waves, oceanic currents) has been little studied. In this work, the morphodynamic response to different hydrodynamic forcing is evaluated from sedimentological and geomorphological analysis in seasonal and medium term (19 years) scale in Palmeras beach, located in the southwest of Gorgona Island National Natural Park (NNP), a mesotidal rocky island on the Colombian Pacific continental shelf. Palmeras is an important nesting area of two types of marine turtles, with no anthropogenic stress. In the last years, coastal erosion has reduced the beach width, restricting the safe areas for nesting and conservation of these species. Until now, the sinks, sources, reservoirs, rates, and paths of sediments were unknown, as well as their hydrodynamic forcing. The beach seasonal variability, from October 2010 to August 2012, was analyzed based on biweekly or monthly measurements of five beach profiles distributed every 200 m along the 1.2 km of beach length. The main paths for sediment transport were defined from the modeling of wave currents with the SMC model (Coastal Modeling System), as well as the oceanic currents, simulated for the dry and wet seasons of 2011 using the ELCOM model (Estuary and Lake COmputer Model). Extreme morphologic variations over a time span of 19 years were analyzed with the Hsu and Evans beach static equilibrium parabolic model, from one wave diffraction point which dominates the general beach plan shape. The beach lost 672 m3/m during the measuring period, and erosional processes were intensified during the wet season. The beach trends responded directly to a wave mean energy flux change, resulting in an increase of up to 14 m in the width northward and loss of sediments in the beach southward. This study showed that to obtain the integral morphodynamic behavior of a rocky beach it is necessary to combine information of hydrodynamic, sedimentology and geomorphology in different time scales.

River mouths are potentially abundant locations for the exploitation of the clean and renewable salinity gradient energy (SGE) as here perpetually fresh water mixes with saline seawater. However, the practical yield of SGE depends on the spatiotemporal variability of the salinity structure. Here we show this relationship for exemplary river mouths. Depending on characteristics of the salinity structure, SGE resources can be reduced to only 0.2% of the theoretical potential. We derive a descriptor for a quick general assessment of the site specific potential and propose a classification of river mouths according to their suitability for SGE generation. It is shown that the tidal range is the most limiting factor for the harnessing of SGE at river mouths. Systems with a tidal range greater than 1.2 m seem not to be suitable locations.

In order to implement osmotic power as a renewable energy source it is necessary to take into account the site-specific characteristics of any river mouth location where a project is proposed. This includes the salinity structure, inter- and intra-annual flow variations, ecological and social restrictions of the flow extraction, among others. Using the case of a location with suitable conditions for osmotic power, the Leon River mouth at the Colombian Caribbean Coast is analyzed in detail. A discharge analysis is undertaken to determine the appropriate size of an osmotic power plant by studying the relationships of the flow extraction with the installed capacity, load factor and yearly generation of the power plant. Furthermore, hydrological and ecological characteristics of the river are taken into account. Once the design flow is determined, the impact of the flow extraction on the salinity structure is analyzed for different climatic scenarios defined by the ENSO phases. The developed methodology can be taken as a basis to assess the osmotic power potential of other rivers on a worldwide level.

Colombia's exclusive location surrounded by the warm tropical waters of the Caribbean Sea and the eastern equatorial Pacific Ocean make it a suitable region for ocean thermal energy conversion (OTEC). These are systems that can produce significant amounts of renewable electricity. From the assessment of the temperature gradient and the bathymetric, environmental and socio-economical characteristics, the maritime area around the island of San Andres (in the northwestern Caribbean Sea) was found to be ideal for an OTEC facility since sea surface temperature varies only slightly during annual and interannual timescales. The thermal difference encountered from the surface to a depth of 1000 m is always around 22°–24 °C and cold waters are available for intake at around 450–750 m, within a short horizontal distance from the coast (less than 2.5 km). At these depths, the 20 °C thermal gradient required for OTEC operations is achieved. Furthermore, winds, waves and surface currents around the island are of relatively weak intensity. Presently, energy sources based entirely on Diesel generators are inducing negative impacts on the sustainable development of the region and on the fragile marine ecosystem. An environmentally friendly 10 MW OTEC facility could be part of future energy and water management solutions for the island. It would cover nearly 50% of total electricity demands and provide important additional advantages such as chilled soil agriculture, aquaculture, freshwater, mariculture and seawater air conditioning.

The lack of hydrological data has been identified as one of the major obstacles facing the effective evaluation of hydraulic and hydrological interventions in the field. Traditional methods of data collection have proven to be generally expensive and particularly risky under high flow conditions. A method for quantifying hydrodynamic variables, such as surface flow velocity and discharge volume was developed in a laboratory setting using video images. This method explores several innovative image analysis techniques, specifically the Image Variance (IV) and Threshold Segmentation with Path Discretization (TSPD), where the basics steps comprise image capture, rectification and data extraction. Measurements obtained from conventional instruments and data extracted from video images were compared and exhibited less than 2.5% difference. It can be concluded that under laboratory conditions it is possible to obtain reliable velocities and discharges from video techniques, without being in contact with the flow.

There are great difficulties in properly evaluating the power present in waves in the Caribbean Sea due to of the scarcity of marine instrumentation and the reduced length of the existing records. This research aimed to design a new methodology for estimating wave power potential in places lacking instrumentation by using reanalysis wind and wave generation models to generate hourly synthetic wave information (maps and wave series), which was later compared and corrected with nearby buoy measurements. Nested runs of the models allowed the results to be downscaled and detailed wave power maps to be created. The best sites for a possible wave farm could then be identified. These maps were built from the propagation of characteristic sea-states of the synthetic series, and were chosen using joint probability, power percentiles and the k-means clustering algorithms. New series were generated in the chosen locations and processed to determine the wave power potential in different time scales. Isla Fuerte, a small non grid-connected island in the Colombian Caribbean, served as a case study for the implementation of the methodology.

Even though different authors have presented procedures for camera calibration in environmental video monitoring, improvements in the robustness and accuracy of the calibration procedure are always desired and in this work the Levenberg-Marquardt method is included in the camera calibration process for environmental video monitoring images as a way to improve the robustness of the camera calibration when a low number of control points is available without using laboratory measurements. The Pinhole model and the Levenberg-Marquardt method are briefly described and a four step camera calibration procedure using them is presented. This procedure allows users to use ground control points to estimate all the Pinhole model parameters, including the lens distortion parameters and its implementation results with laboratory data are compared with the results presented by other authors. The procedure is also tested with field data obtained with cameras directed toward the beaches of the city of Cartagena, Colombia. The results show that the procedure is robust enough to be used when just a low number of control points are available, even though a large number of GCP is recommended to obtain high accuracy. (c) 2012 Elsevier Ltd. All rights reserved.

A model that describes the weathering of crude in an oil spill caused by interaction with the atmosphere and the ocean was developed. This model was adapted to the Colombian crudes Cusiana (°API43.2) and Vasconia (°API20.7). To calibrate the model, evaporation and emulsification experiments were carried out at conditions similar to those of an oil spill in the Colombian Caribbean Sea. The dependence of evaporation with wind velocity, not predicted by the state-of-the-art models, was captured by a correlation for the mass transfer coefficient calculated from the experimental data. Emulsification rate, maximum water content and required evaporation to form an emulsion were determined and their values explained considering the effect of wax precipitation for Cusiana crude oil. When compared to well-established weathering software, such as ADIOS, the proposed model predicts the weathering of Colombian oils in a way that better agrees with the experiments conducted in the laboratory.

A critical factor when undertaking proper coastline management is the availability of reliable data, allowing those responsible to make informed decisions about land use and its impact on natural resources. Marine resource data (bathymetry, time-series of waves, coastal use levels, etc.) have often been difficult for policy-makers to obtain and use, given the high costs involved and difficulties in their application and interpretation. In cases where a source of coastline data is available, it is important that it be sufficiently complete to compare habitat changes (in morphology and use) that are only observable over a period of years. Thus, it is necessary to look for alternative methods to obtain this long-term information. The availability of new data-gathering techniques for the study of coastlines and coastal processes, such as remote sensors and underwater photography and videography, has increased during the last decade. One of the principal research applications of these techniques is bathymetry. This paper presents state-of-the-art image-based models that allow the construction of topo-bathymetric shore data. The Physical and Statistical Detection Model (PSDM), which constitutes the core of this research, is discussed and validated. The PSDM is based on a combination of six different algorithms that describe the shoreline features, and it assigns physical and statistical criteria to the detection process. In conclusion, a numerical tool based on video systems is introduced which shows great potential for monitoring coastal issues and supplying data to aid technicians and shoreline managers.

Financial institutions operate a supply chain where only one product is moved across the network. Although the cash is kept in several nodes to service the demand of final customers, availability causes opportunity cost related with its investment options. When planning the inventory of cash that should be maintained across the network, transportation decisions are also expected to be made. Cash transportation has a high cost, associated with the high risk of theft. Increasing the inventory can reduce the need for transportation, but the opportunity cost can be very high. Moreover, the inventory is also related with the service level perceived for final customers; therefore because of low inventory some people are not able to make some transactions. The aim of this work is to find optimal decisions related with cash inventory and transportation across the network, trying to balance the cost of the service and the quality perceived for final users.

8 pages, 9 figures, 1 table, 1 appendix, Images from an Argus beach monitoring station were analyzed to count the number of people on two city beaches in Barcelona (NW Mediterranean) every hour for 4 years. Daily, weekly, seasonal, and interannual user distribution patterns were clearly established. Two different fit models were applied to the data based on a Fourier polynomial and nonlinear criteria, including external factors such as temperature and wind conditions, as well as predisposition factors. Finally, the evolution of beach users was compared with morphological beach changes caused by natural processes and human action. The results demonstrated that video observations provide a suitable method for counting people on the beach that could be useful for a number of coastal management applications, This work was funded by the Spanish Ministry of Science and Technology within the project PUDEM (REN2003-06637-C02). E. Ojeda is supported by a University Professors Formation grant from the Spanish Ministry of Education and Science

The use of video imaging and images processing techniques is increasingly used worldwide to deal with a variety of coastal engineering aspects. The European project COASTVIEW (EVK3-CT-2001-0054) has emphasised various coastal engineering fields for which video systems could be used in support to more traditional procedures of data acquisition and viewed as practical tools for an integrated management. The study presented here specifically deals with the use of video for assessment of the recreational use of beaches and is centred, through the example of the « Puntal » beach at Santander (Spain), on the analysis of the spatial and temporal distribution of the users on the beach.