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The effect of vegetation patchiness on solitary wave propagation, attenuation and wave-induced forces is studied both experimentally and numerically. Vegetation patchiness is simulated with rigid cylinder configurations built by one, eight and four patches tested under emergent, near emergent and submerged conditions. These configurations are parameterized by means of a new parameter (equivalent length, Le), which is used to relate cylinders distribution with wave attenuation capacity. This new parameter allows comparing results for the three patches configurations. Larger attenuation rates are found for higher wave heights and shorter wave periods. The influence of water depth is also considered by means of the submergence ratio (SR) in order to account for the percentage of water column affected by vegetation. Higher attenuation rates are obtained for emergent conditions. High correlations are found between wave attenuation and a new set of parameters, the depth wave number (kLe × SR), that accounts for submergence conditions and field characteristics and a new Reynolds number ( R e s L e ), that is calculated considering the field vegetation dimensions affecting the flow. Experimental results are extended using IHFOAM, a three dimensional Navier-Stokes equations solver, to analyze wave forces on individual cylinders and wave propagation patterns showing the variability of forces magnitude and direction associated to vegetation patchiness.

We use a numerical model, already validated for this purpose, to simulate the effect of wave frequency spread on wave transformation and swash amplitudes. Simulations are performed for planar beach slope cases and for offshore wave spectra whose frequency spread changes over realistic values. Results indicate that frequency spread, under normally approaching waves, affects swash amplitudes. For moderately dissipative conditions, the significant infragravity swash increases for increasing values of the offshore frequency spread. The opposite occurs under extremely dissipative conditions. The numerical analysis suggests that this inverted pattern is driven by the effect that different distributions of incoming long?wave energy have on low?frequency wave propagation and dissipation. In fact, with large frequency spreads, wave groups force relatively short subharmonic waves that are strongly enhanced in the shoaling zone. This process leads to an infragravity swash increase for increasing frequency spread under moderately dissipative conditions in which low?frequency energy dissipation in shallow water is negligible or small. However, under extremely dissipative conditions, the significant low?frequency energy dissipation associated with large frequency spreads overturns the strong energy growth in the shoaling zone eventually yielding an infragravity swash decrease for increasing frequency spread. This work has been funded under (1) the RETOS INVESTIGACION 2014 (Grant BIA2014-59718-R) program of the Spanish Ministry of Economy and Competitiveness and (2) the NEPTUNE 2 project, L. R. 7/2007 by Regione Autonoma della Sardegna.

Historic coastal structures have played a key role in small- to medium-size ports, being the driving force for the local development of coastal communities. Because coastal managers require reliable risk-based analysis of the whole life cycle of these coastal structures, previous lifetimes should be studied. This is a differentiating factor with respect to the newly built breakwaters. For this reason, in this work, a methodology for assessing how the hydraulic performance of an expired lifetime has evolved over the years is presented. It is performed following a probabilistic approach due to the uncertainty related to both the involved variables (wave climate, geometrical and structural breakwater variables) and the hydraulic response of the structure. The first ones are characterized by reliable probability distribution functions. The second ones are characterized by reliable formulae for the analysis of the hydraulic response. However, their non-conventional designs located in shallow-water locations require site-dependent formulae. To overcome this problem, a novel methodology to apply CFD numerical models is presented. Finally, it is integrated in a high-resolution time-dependent probabilistic methodology which takes into account the stochastic behaviour of all the involved variables, coastal and structural processes with a good uncertainty level. This article is part of the theme issue ‘Environmental loading of heritage structures’.

The binding of Zn(II) cations to a pentafoil (51) knotted ligand allows the synthesis of otherwise inaccessible metallated molecular pentafoil knots via transmetallation, affording the corresponding ‘first sphere’ coordination Co(II), Ni(II) and Cu(II) pentanuclear knots in good yields (≥85 %). Each of the knot complexes was characterized by mass spectrometry, the diamagnetic (zinc) knot complex was characterized by 1H and 13C NMR spectroscopy, and the zinc, cobalt and nickel pentafoil knots afforded single crystals whose structures were determined by X-ray crystallography. Lehn-type circular helicates generally only form with tris-bipy ligand strands and Fe(II) (and, in some cases, Ni(II) and Zn(II)) salts, so such architectures become accessible for other metal cations only through the use of knotted ligands. The different metallated knots all exhibit ‘second sphere’ coordination of a single chloride ion within the central cavity of the knot through CH…Cl- hydrogen bonding and electrostatic interactions. The chloride binding affinities were determined in MeCN by isothermal titration calorimetry and the strength of binding shown to vary over three orders of magnitude for the different metal-ion−knotted-ligand second sphere coordination complexes.

This work has been part of the research project DOVICAIM (RTC-2014-3077-4), which was financially supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) within the National Program for Research Aimed at the Challenges of Society.

Jamaica, like other Caribbean and island nations is at high risk from coastal flooding and related hazards. Vulnerable coastal communities in Jamaica receive significant flood protection benefits from natural habitats like mangroves and coral reefs, even though these habitats are threatened by human development and activity and by natural stressors such as sea-level rise and climate change. As coastal flooding and habitat loss increase, there is great imperative among national disaster risk reduction agencies, conservation agencies and international aid institutions in Jamaica, to quantify the economic value of conserving and restoring mangrove habitats for risk reduction and to thereby inform national risk reduction, climate adaptation and conservation plans. This technical report provides an ecological, economic and social assessment of the habitat status, risks, costs and flood protection benefits of mangroves in Jamaica with a focus on their role in coastal flood risk reduction. This work aims to support decisions for sustainable and cost-effective approaches for mangrove management and flood risk reduction. First, authors assess the current status and recent trends in the distribution of mangroves in Jamaica. We then review the costs of restoration mangrove projects across Jamaica and the wider Caribbean. Using connected assessments, authors consider the nationwide restoration potential for mangroves. The authors then focus on a rigorous nationwide assessment of flood risk and the risk reduction benefits of mangroves to people and property across Jamaica.

Coastal development and climate change are dramatically increasing the risks of flooding, erosion, and extreme weather events. Coral reefs and other coastal ecosystems act as natural defenses against coastal hazards, but their degradation increases risk to people and property. Environmental degradation, however, has rarely been quantified as a driver of coastal risk. In Quintana Roo, Mexico, a region on the Mexican Caribbean coast with an annual tourism economy of 10 billion USD, coral reefs constitute a natural barrier against flooding from hurricanes. This study spatially quantifies the risk reduction benefits of the Mesoamerican Reef in Quintana Roo for people, buildings, and hotel infrastructure. The risk reduction benefits are substantial. For example, the reefs prevented 43% additional damage during Hurricane Dean (2007) and provide nowadays hazard risk reduction for 4.3% of the people, 1.9% of the built capital, and 2.4% of the hotel infrastructure, per year. The annual benefits are estimated in 4,600 people, 42 million USD damage prevention for buildings, and 20.8 million USD for hotel infrastructure. The study also compares the risk reduction of coral reefs with (i) the protection offered by dunes and (ii) the increase in coastal risk from sea-level rise. The risk reduction of dunes is more critical where there are no coral reefs offshore and for small return-periods storms. Sea-level rise, however, will make the more frequent storms more impactful and will drive significant increases in annual expected damages across the region. However, we demonstrate that, in coral reef environments, the contribution of reef degradation to coastal risk is larger than the expected increase in risk from sea level rise. However, the spatial distribution of the risk reduction benefits from reefs differs for people and infrastructure, and in particular for hotels, which receive the most protection from reefs. Furthermore, many sections present larger benefits than the typical costs of restoration. This valuation makes a compelling case for protecting and maintaining this natural infrastructure for its risk reduction service, but also allows the development of piloting innovative strategies, such as risk finance and insurance strategies, that can align environmental and risk management goals.

In this work, we present several applications of the 2D-3D multi-domain couplings for Navier-Stokes models developed and validated in its companion (Di Paolo et al., submitted). The methodology is used to carry out some relevant simulations which include long regular and irregular waves, solitary wave propagation on a shallow foreshore, focused wave group transformation on a planar beach, wave impact on a cylinder and finally, the numerical twin of a complex laboratory experiment to analyse the performance of a perforated breakwater under wave action. Results agree well with the full 3D simulations and laboratory experiments and demonstrate the feasibility of using the 2D-3D coupled methodologies presented in Part I to successfully replace full 3D modelling. For all the cases considered, the application of coupled methodologies have resulted in a drastic reducing of the computational time without decreasing the accuracy of the full solution.

Estimation of the flow energy dissipation induced by an ecosystem that accounts for its characteristics (i.e. biomechanical properties, morphology, density) and the incident hydrodynamic conditions is crucial if ecosystem-based coastal protection measurements want to be implemented. Characterization of a vegetated ecosystem by measuring leaf traits, biomechanical properties of plants and the number of individuals per unit area involves a lot of effort and is case-specific. Standing biomass can be a unique variable defining the flow energy attenuation capacity of the ecosystem. To explore its relation to the induced energy attenuation on the flow, a new set of experiments using real vegetation with contrasting morphology and biomechanical properties, and subjected to different incident flow conditions is presented. The obtained standing biomass-attenuation relationships will help to quantify the expected coastal protection provided by different vegetated ecosystems based on their standing biomass and the flow conditions.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/-qaKkBWZApk

The use of CFD for numerical representation of laboratory wave flume and basins, commonly known as numerical wave tanks (NWT), has become more popular in recent years with the aim of improving knowledge in the field of wave-structure interaction (WSI), both fixed and floating, due to advances that have been made in numerical modelling, mainly with the reproduction of three dimensional problems. The use of this technique is displacing even traditional approaches based on the use of potential flow equations, due to the versatility provided by the CFD approach, which allows considering nonlinear interactions between structures and waves, and above all, extreme events such as wave breaking. However, implementation of these models as a complementary tool to physical modeling facilities is not yet standardized and requires further development to hybridize these two techniques, numerical and experimental, in order to obtain a better knowledge of physical processes. Implementation still requires overcoming existing modeling limitations and the additional steps to be taken focus on the following areas are: a) numerically mirror wave generation and active/passive absorption in physical installations; b) numerical resolution of WSI problems, which to date depends on each WSI case; c) computational cost, which may be the bottleneck for NWT implementation; and, finally, the most important feature that is where the added value of the hybrid approach lies, d) the exchange of information between the laboratory measurements and the results of the numerical simulations in order to obtain a better understanding of WSI problems. This paper will present an analysis of the main aspects described above for the implementation of hybrid techniques for the study of WSI problems (floating and fixed). The latest advances in modeling developed with IHFOAM solver (ihfoam.ihcantabria.com), and physical modeling procedures to link laboratory and numerical tools will be presented. The main objective is establishing a standard procedure to implement this technique in any physical installation.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/6mAQccSrREM

A regression-guided classification is implemented in statistical downscaling models based on weather types for downscaling multivariate wave climate and modelling extreme events. The semi-supervised method classifies the atmospheric circulation conditions (predictor) and the estimations from a regression model linking the circulation with local marine climate (filtered predictand). A weighted factor controls the influence of the predictor and predictand in the weather patterns to improve the performance of the classification to reflect local marine climate characteristics. In addition to the analysis of the variance explained by the predictor and the predictand, the selection of the optimal value of the weighted factor is based on the predictand response in order to avoid subjectivity in the solution. The statistical models using the guided classification are applied in the North Atlantic. The new technique reduces the dispersion of the multivariate predictand within weather types and improves the model skill to downscale waves and to reproduce extremes.

Focused on offshore wind energy operation and maintenance applications, this work presents a detailed accessibility analysis of the North Sea. After a review of existing normative dedicated to inspection and access of offshore wind turbines, a rigorous mathematical formulation of relevant accessibility parameters is given by means of the set theory. Long-term and high-resolution metocean data are extracted from reanalysis databases and used to evaluate spatial and temporal variability of such parameters. Respectively restricted by significant wave height and mean wind speed, access by workboat and helicopter is evaluated. Being affected by both wave height and wind speed. Access by offshore crane is also analyzed. It resulted that the UK coast and the southern region of the North Sea are highly accessible, while the coast of Denmark and Norway undergoes more severe metocean conditions. This is, however, balanced by a higher wind resource. Moreover, a strong seasonality is ascertained, together with a drastic reduction of accessibility during daytime in a vast part of the basin. Accessibility during daytime in winter and autumn is very difficult for the whole North Sea. Among the studied farms, Dogger Bank is by far the one with the highest resource and lowest accessibility, while Thorntonbank III the one with the lowest resource and highest accessibility. In addition, accessibility is non-linearly related to wind speed and wave height limits chosen for the access strategies covered. Copyright © 2016 John Wiley & Sons, Ltd.

The first regular homometallic ring containing anodd number of metal centers is reported. The ring wassynthesized by means of amine-templated self-assembly.Extensive physical characterization studies, including magneticmeasurements, powder inelastic neutron scattering (INS), andDFT calculations, show that the molecule has a near perfectmatch to the expected behavior for a frustrated system with thelowest energy pair of S=1/2 spin states separated by only0.1 meV (0.8 cm¢1).

Offshore wind energy is moving towards a future where the main challenge is to cope with the increasing water depth needed to access more and better wind resources. One of the first steps to be undertaken is the development of floating structures to support either wind turbines or measurement devices for the proper characterization of wind energy resources. The use of floating devices for measuring wind speed involves a number of uncertainties not presented by seabed fixed systems. These sources of uncertainty or error are present both in instantaneous wind measurements and averaged (10 min or hourly) values because of (i) variability in the measurement height, (ii) the tilt of the anemometer and (iii) the relative velocity between the anemometer and the wind, among others. In this paper, a methodology for assessing the error in the wind measurement characterization because of the movement of a floating meteorological mast is presented. By the numerical simulation of a floating mast, the short- and long-term error in the characterization of the wind at different heights has been evaluated. In general, the error because of the tilt can reach up to 80% of the total error; the error because of the variation of the vertical position of the anemometer reaches values of up to 15% in some cases; moreover, the error associated with the relative velocity between the anemometer and the wind, for averaged values, is significantly less. Finally, it can be concluded that the total error is lower than 0.5% for 10 min averaged wind speed of up to 24 m/s. Copyright © 2016 John Wiley & Sons, Ltd.

This paper presents a methodology to assess the walk-to-work accessibility of a floating wind turbine. The system composed by the vessel and the platform is modelled in the frequency domain as a rigid, possibly constrained multibody system. Non-linear actions, such mooring and viscous forces are linearised. Extreme maxima for the response variables are calculated assuming that crests are Rayleigh distributed. Two vessels are studied: a catamaran equipped with fender, and a supply vessel mounting a motion-compensated gangway. For the catamaran, accessibility is possible when no-slip conditions between the vessel fender and the ladder landing platform are ensured. For the supply vessel, accessibility is possible when the gangway motions are below the hydraulic system compensation limits. The catamaran is able to handle wave heights up to 2 m, provided that it can work under head sea conditions and take advantage of the shielding effect of the platform. The supply vessel allows personnel transfer with wave heights up to 5 m, but it is important that roll motions are not excited. The proposed methodology and the calculated maps are a valuable source of information for decision-making during personnel transfer to and from offshore floating platforms.

Based on energy conservation a new analytical formulation for the evaluation of wave damping under the combined effect of waves and both following and opposing currents is presented. The formulation obtained for regular and random waves allows the derivation of analytical expressions for the vegetation drag coefficient as a function of wave damping parameters. These parameters are calibrated using a unique experimental set obtained in a large-scale wave basin considering the interaction of waves and currents with real vegetation representative of salt marshes, namely Spartina anglica and Puccinellia maritime. Comparisons show the quality of the analytical formulation under different hydrodynamic conditions, vegetation species and various Reynolds numbers formulated in terms of plant characteristics such as the deflected plant length accounting for the flow-induced bending of the vegetation. The new formulation can be useful to be implemented in phase averaged and phase resolving numerical models of wave propagation.

In recent years, the impact of climate change on sea surface waves has received increasingly more attention by the climate community. Indeed, ocean waves reaching the coast play an important role in several processes concerning coastal communities, such as inundation and erosion. However, regional downscaling at the high spatial resolution necessary for coastal studies has received less attention. Here, we present a novel framework for regional wave climate projections and its application in the European region. Changes in the wave dynamics under different scenarios in the Northeast Atlantic Ocean and the Mediterranean are analyzed. The multi-model projection methodology is based on a statistical downscaling approach. The statistical relation between the predictor (atmospheric conditions) and the predictand (multivariate wave climate) is based on a weather type (WT) classification. This atmospheric classification is developed by applying the k-means clustering technique over historical offshore sea level pressure (SLP) fields. Each WT is linked to sea wave conditions from a wave hindcast. This link is developed by associating atmospheric conditions from reanalysis with multivariate local waves. This predictor–predictand relationship is applied to the daily SLP fields from global climate models (GCMs) in order to project future changes in regional wave conditions. The GCMs used in the multi-model projection are selected according to skill criteria. The application of this framework uses CMIP5-based wave climate projections in Europe. The low computational requirements of the statistical approach allow a large number of GCMs and climate change scenarios to be studied. Consistent with previous works on global wave climate projections, the estimated changes from the regional wave climate projections show a general decrease in wave heights and periods in the Atlantic Europe for the late twenty-first century. The regional projections, however, allow a more detailed spatial characterization of the projected changes under different climate scenarios. For example, changes in significant wave heights for the RCP8.5 scenario for the 2070–2099 time period indicate a general decrease of about 10 cm in Southern Europe (Portuguese, Spanish and French coasts) with respect to present conditions. This decrease is due to a higher occurrence of dominant and moderate Azores high pressure systems over the North Atlantic Ocean and a decrease in the persistence of intense low pressure systems at high latitudes.

In this work an analysis of suitable locations for the development of wave energy farms is carried out based on representative operation and maintenance parameters. The analysis is applied globally on the basis of long-term global climate data set. Availability and accessibility levels are assessed first by considering different wave height thresholds. Secondly, the O&M access limits are quantified in terms of the weather windows and waiting period between them considering different windows lengths and scenarios. Finally, the O&M cost per kW h is calculated for a wave energy converter based on a point absorber concept. O&M costs has been calculated following the methodology proposed on Guanche et al. (2014). As expected, results show that locations with mild wave climate have very low O&M costs per kW h. Some areas with high wave resource, such as Scotland, Spain or Nova Scotia present reasonable O&M costs compared to the power production in these areas. However, other locations with high resource like Chile or Australia resulted in extremely high O&M costs due to the inaccessibility of these sites during long periods of time.

This paper presents an innovative vertical breakwater cross-section integrating an overtopping wave energy converter, named OBREC-V, and the analysis of its hydraulic performance and stability response to hydraulic loading. The structure is composed of a vertically-faced caisson with a sloping ramp on the top, a reservoir and a set-back crown-wall. The analysis of the structure is carried out by performing numerical simulations based on the Volume-Averaged Reynolds Averaged Navier-Stokes (VARANS) equations. The numerical simulations are performed to compare the performance of a traditional and innovative vertical caissons under the action of irregular waves, in terms of wave reflection, overtopping and wave acting forces. Results show that the reflection coefficients are lower than those computed in front of the traditional breakwater, with a reduction of up to the 40%. New formulations are proposed to better estimate the reflection coefficient and the wave overtopping at the rear side of the structure taking into account the non-conventional geometry of the device. The analysis of the forces indicate that the non-conventional geometry of the innovative OBREC-caisson increases the overall stability of the structure. The values of the safety factor against sliding, Cs, on innovative caissons are similar or greater than those calculated on the traditional vertical structure for almost all the tests. The downward force on the ramp and reservoir and the time lag between the vertical and horizontal forces, lead to a significant reduction of the maximum destabilizing forces Fs in the innovative breakwater, whose values range between 60 and 80% of the ones computed on the traditional structure. The obtained results show the co-benefits, in terms of functionality and hydraulic stability, that an OBREC-V entails with respect to a traditional vertical breakwater.

This paper analyses the importance of mooring design parametrisation on the dynamic behaviour of mooring loads. An exhaustive sensitivity analysis is performed to evaluate the variability of mooring loads because of inaccuracies in the definition of model inputs, including physical and numerical parameters. Results show a relevant dependence on the length and significance in other parameters, such as the weight together with the hydrodynamic equivalent diameter and the drag forces. An inaccuracy below 1% in the mooring reference length can generate loads of up to twice the design, and an incorrect definition of the weight or the drag coefficient in the mooring design can lead to a design load variability of up to 30%. Stiffness plays a crucial role in snap events, reaching load differences of 19% depending on the stiffness selected. This research is based on a set of numerical models capable of predicting the mooring system response. A dynamic numerical model with two schemes of resolution is implemented and calibrated according to an experimental test campaign. Other sources of results provided by a quasi-static model and commercial software, Sesam (DNV-GL), are incorporated. In general, the dynamic numerical models show a good accuracy with an experimental database composed by a set of 2D prescribed movement tests at the fairlead of the mooring system.

Climate change is and will continue altering the world's coasts, which are the most densely populated and economically active areas on earth and home for highly valuable ecosystems. While there is considerable relevant research, in the authors' experience this problem remains challenging for coastal engineering. This paper reviews important challenges in this respect and identifies three key actions to address them: (a) refocusing traditional practice towards more climate-aware approaches; (b) developing more comprehensive risk frameworks that include the multi-dimensionality and non-stationarity of their components and consideration of uncertainty; and (c) building bridges between risk assessment and adaptation theory and practice. We conclude that the way forward includes numerous activities including increased observations; the attribution of coastal impacts to their drivers; enhanced climate projections and their integration into impact models; more impact assessments at the local scale; dynamic projections of spatially-distributed exposure and vulnerability; and the exploration of inherently adaptive options. Given the complexity of the possible solutions, more practical guidance is required.

Mooring systems are under a cyclic loading process caused by the randomness of metocean conditions, which could lead to a fatigue failure of the station keeping system. The present paper presents an innovative methodology for the assessment of floating offshore wind turbine mooring system fatigue considering the full lifetime of the structure. The method integrates the impact of the life cycle metocean conditions over the dynamic performance of the platform thanks to coupled numerical models, selection and non-linear data interpolation techniques and commonly accepted fatigue approaches. One of the benefits of using this methodology is that there are no uncertainties due to the selection of a reduced set of sea states. The methodology is applied to a set of moorings with different properties in the DeepCwind platform to evaluate the solution which offers the best compromise between size and fatigue damage. Results show that the best long-term mooring behaviour is achieved with a weight of approximately 300 kg/m. A comparison is conducted between the fatigue damage obtained through the life-cycle method and conventional methods. The mean differences observed between the standard and the new method proposed are between 13% and 49% depending on the use of the S–N or T-N curves.

In a context of growing concern about climate change and its potential consequences for coastal systems, adaptation is becoming more important than ever before. This paper presents a national planning framework for adaptation to climate change, which is pioneer in the field as it is multi-sectoral and focuses specifically on coastal areas, pursuing the safety of their communities in an uncertain future. The strategy is statutory as it emanates from the new Spanish Coastal Law, which in addition to many other implications includes the compulsory development of a Spanish Strategy for Coastal Adaptation to Climate Change (SSCACC) and its submission to Strategic Environmental Assessment. This paper covers the fundamental aspects of both the SSCACC and the accompanying Strategic Environmental Study, providing recommendations on the assessment of coastal risks triggered by climate change and extreme events, adaptation and risk reduction planning and implementation, and monitoring. Additionally, this work gives insight into the wide-ranging consultation process carried out prior to the SSCACC's approval and the stakeholders involved, and how the SSCACC handles climate change uncertainty and struggles for overcoming barriers.

Numerical modelling of floating bodies is still being a very challenging issue, especially for large body displacements. Despite of the good performance of potential flow models in predicting floating body dynamics, there are still physical processes which are not well reproduced with that approximation. Their strong assumptions yield a lack of accuracy when high non-linear effects become predominant. In addition, the presence of restrictions to motion induced by mooring elements also introduces additional non-linear features which are sometimes out of the framework of the use of potential flow models. The use of CFD approach overcomes potential model limitations especially for non-linear effects. When CFD models are applied to solve waves and current interaction with floating bodies, several issues arise such as the numerical treatment of the floating element, mooring implementation and also the computational cost. Although several approaches are available in literature regarding the numerical implementation of floating bodies, the use of the Overset mesh appears as the more suitable one for large body displacement. Although accurate results have been obtained with re-meshing or even morphing techniques, large mesh deformation can yield into non-acceptable skewness and aspect ratio for the cells, consequently inducing numerical instabilities. In this work, we will present a numerical analysis of wave and current interaction with floating bodies. The objective of the work is to present a set of numerical implementations performed in OpenFOAM environment with the use of the Overset mesh method to study moored floating body dynamics due to the combined action of waves and current. The implementations, included in IHFOAM (www.ihfoam.ihcantabria.com) are a new set of boundary conditions to generate waves and current without the use of relaxation zones. The main consequence is that the computational cost can be reduced due to the use of smaller domains. In addition, the implementation of mooring will be also presented in order to extend the use of the model to realistic conditions. Numerical model predictions compared with laboratory data of wave interaction with moored floating bodies have been performed showing a high degree of agreement. Comparison of floating body displacement and mooring tension will be presented. The combined effect of waves and current, traveling in the same and in opposite directions than waves, and their interaction with floating bodies and mooring will be also studied. Results will show the applicability of current method to model floating bodies.

In the last years, the use of floating concrete caissons in coastal infrastructures has been generalized: docking structures, vertical breakwater and special floating structures. In this field, one of the most important and less analyzed stages of the marine works is the sinking process of the floating caissons. The test campaign presented in this work is innovative in scale (1:12) and includes an analysis of the different stages of a floating caisson during its life cycle: detached concrete caisson, caisson positioning and sinking and berthed floating caisson, resulting in more than 130 tests performed. Movements and tensions have been analyzed for a wide array of sea states and different configurations of mooring systems and horizontal layouts. A new tool for dynamic positioning control was designed and developed as part of the test campaign. The design of this tool has led to the development of a specific numerical model that reproduced the dynamic behavior during sinking. The dynamic positioning control was implemented in the physical model campaign, which has meant an important advance in the construction process of maritime infrastructures. Moreover, the campaign carried out has allowed the validation and calibration of the tools developed, allowing all the work to reduce costs and increase the safety of these types of marine operations.

this manuscript describes in a didactic manner the methodology, development, implementation and evaluation of different control strategies to maximize the energy obtained from wave energy converter (WEC) devices. Having this aim in mind, a power take off (PTO) system with different control strategies will be presented. The chosen take off system is an oscillating water column converter (OWC), a device that uses a Wells air turbine as the primary energy converter with a Doubly Fed Induction Generator (DFIG) as the secondary. The Wells turbine contributes to the robustness of the system because it requires no additional parts to produce unidirectional rotation from the reversing oscillating flow, while the DFIG offers the best capabilities when operating in both sub- and super-synchronous modes. The proposed scheme is based on the NEREIDA MOWC demonstration project, a breakwater wave plant located in the Basque location of Mutriku. This material and teaching experience corresponds to a Master in Control at the Engineering Faculty of the Basque Country University.

This article covers research into rotational speed control for oscillating water column converters (OWC). The primary focus is the improvement of the Wells turbine performance by controlling its rotational speed. In this sense, the proposed control scheme has been implemented based on the NEREIDA MOWC demonstration project, a breakwater wave plant located in the Basque location of Mutriku, using Wells turbines and induction generators, so as to advance wave energy converter (WEC) devices. The variable control speed operation involves the use of the Doubly-fed Induction Generator (DFIG) as the main element of the WEC system. By controlling the slip of the generator it is possible to determine the speed of the turbo-generator set. The primary aim of the speed control is to maximize the efficiency of the Wells turbine due to its non-uniform response in the performance, since it mainly depends on the rotational speed. Furthermore, by means of the speed control it is possible to avoid the stalling phenomenon, and therefore the efficiency drop in Wells turbines.

This work represents the first attempt to study the behavior of sea level extreme events nearshore using satellite altimetry data. A novel approach based on the application of a nonstationary extreme model to nontidal residual monthly maxima from remote data is presented. With the aim of countering the lack of accuracy, an extreme scale factor to correct satellite data is defined. The extreme scale factor depends on local morphology and its definition makes use of the information provided by 14 tide gauges along the North American East Coast. The methodology is validated using eight additional tide gauge records along the study region. Low differences on values associated to high return periods using satellite and tide gauge data input are found for all the validated locations. Besides, a regional study of the climate variability of extreme sea levels from satellite is also presented. The found climate patterns strongly agree with the historical climate variations from in situ data. Results show a great potential of this approach, especially at those locations where in situ information is not available. The work reported here was partially supported by the Spanish Government through the grant PORTIO (BIA2015-70644-R); project ECLISEA, part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by UC-IHC, HZG, BRGM, NCSRD, and CNRS and cofunding by the European Union (Grant 690462), and the US DOD Strategic Environmental Research and Development Program (SERDP Project RC-2644).

Coral reefs can provide significant coastal protection benefits to people and property. Here we show that the annual expected damages from flooding would double, and costs from frequent storms would triple without reefs. For 100-year storm events, flood damages would increase by 91% to $US 272 billion without reefs. The countries with the most to gain from reef management are Indonesia, Philippines, Malaysia, Mexico, and Cuba; annual expected flood savings exceed $400 M for each of these nations. Sea-level rise will increase flood risk, but substantial impacts could happen from reef loss alone without better near-term management. We provide a global, process-based valuation of an ecosystem service across an entire marine biome at (sub)national levels. These spatially explicit benefits inform critical risk and environmental management decisions, and the expected benefits can be directly considered by governments (e.g., national accounts, recovery plans) and businesses (e.g., insurance)., Coral reefs provide significant coastal protection from storms but they have experienced significant losses. Here the authors show that the annual damages from flooding would double globally without reefs and they quantify where reefs provide the most protection to people and property.