Analysis of the optimal deployment location for tidal energy converters in the mesotidal Ria de Vigo (NW Spain)

The potential power output expected from the installation of a tidal farm near the mesotidal Ria de Vigo (NW Spain) is assessed using two different tidal stream energy converters (TEC). For this, the results of a previous resource assessment based on a 28-day long hydrodynamic simulation are used. From this data we identify the areas susceptible of hosting the farms, select the optimal location for them, and assess the total available and extractable energy for each turbine type. Finally, using a simple farm design based on standard inter-turbine separation, we estimate the expected power supplied by the farm. Irrespective of the site, the total available tidal power in the areas susceptible of hosting the farms is around 150 MW; at the optimal location, the hourly extractable power is about 22.5 MW, of which only between 10% and 15% can be harnessed by the designed farms, powering between 4411 and 6638 homes. A local analysis of the most energetic subregions within these sites increases this ratio up to 30%. Nevertheless, the power output is sufficient to fulfil the needs of between 1660 and 2213 households, depending on the chosen site and the selected TEC.Peer ReviewedPostprint (author's final draft

Wave energy potential along the Atlantic coast of Morocco

This study analyses the wave energy resource along the Atlantic coast of Morocco using a 44-year series of data obtained from numerical modeling (hindcasting). The spatial distribution of wave power is analyzed using data from 23 points along that coast. The estimated resources (average wave power up to 30 kW/m and average annual wave energy up to 262 MW h/m) are considerable and slightly lower than at the neighboring Canary Islands. The central part of this area (between latitudes 29°30'N and 34°N) is the most productive, while in the northern and southern parts the resource is significantly lower due to the shadow effect of the Iberian Peninsula and the Canary Islands, respectively. The study of the temporal variability indicates a considerable seasonal trend, being the wave energy resource over four times greater in winter than in summer. Moreover, the power matrices of two wave energy converters (WECs) are considered to estimate the average power output at all the studied points. Finally, a multi-criteria analysis is carried out considering five different factors in order to select the best places for WEC deployment.Peer ReviewedPostprint (author's final draft

Vulnerability of Catalan (NW Mediterranean) ports to wave overtopping due to different scenarios of sea level rise

The final publication is available at Springer via http://dx.doi.org/10.1007/s10113-015-0879-xThe overtopping of port breakwaters may affect the assets located at the breakwater lee side. If adaptation measures are not taken, the sea level rise will increase the overtopping discharges putting those assets at significant risk. This study compares, at a regional scale, overtopping discharges over port breakwaters for three storm conditions (return periods of 1, 5 and 50 years) under present climate as well as for three scenarios of sea level rise based on recent projections. The results indicate that, for the worst storm and sea level rise conditions, the overtopping discharge would not be negligible (larger than 1 l/s/m) in 35 ports (84 %), in contrast to only 18 ports (42 %) being affected under present conditions. In addition, in 28 ports (65 %) the overtopping would be at least one order of magnitude larger than for present conditions. In the case of large storms, in 2 ports the overtopping discharge exceeds 200 l/s/m (the discharge that can initiate breakwater damage) under present conditions, while in the worst scenario of sea level rise the number of ports exceeding this value would be 7. On the other hand, the vulnerability of each port for which overtopping flow is greater than an acceptable discharge flux is assessed, and regional maps of vulnerability are plotted. For the worst storm conditions, 23 % of the Catalan ports have risks associated with overtopping under present climate conditions. This percentage would increase to 47 % in the worst sea level rise scenario.Peer ReviewedPostprint (author's final draft

Correlation of concurrent extreme metocean hazards considering seasonality

Simultaneous occurrence of metocean variables can present a multihazard to maritime systems. However, simplified design approaches to assess simultaneous significant wave heights and wind velocities are lacking, especially if seasonality is considered. This is addressed in this study by using extreme significant wave heights and companion wind velocities recorded in the Gulf of Mexico. Time-dependent, generalized extreme value (GEV) models and classical regression are the basis to propose a simplified approach to estimate correlated extreme significant wave heights and wind velocities associated with given return periods, accounting for seasonality and including measures of uncertainty. It is found that the proposed approach is a new but simple method to adequately characterize the concurrent extreme metocean variables and their uncertainty. It is concluded that the method is an effective probabilistic design tool to determine simultaneous extreme significant wave heights and companion wind velocities for desired return periods and seasonality.The financial support from the Erasmus Mundus Coastal and Marine Engineering and Management (CoMEM) programme and support from Laboratori d’Enginyeria Marítima, Universitat Politècnica de Catalunya and from Universidad de Guanajuato (CIIC 2020 Research Projects) is gratefully acknowledged. Acknowledgments: We thank two anonymous reviewers for their comments, suggestions and constructive criticism. We also thank guess Editor Guido Ventura and the editorial team of Applied Sciences for their help in the editorial process.Peer ReviewedPostprint (published version

Quantification of the tidal stream exergy in the ría de Vigo (NW Spain)

The exergy of the tidal currents in the ría de Vigo area (NW Spain) is quantified using the results of a 28-day long simulation of the tidal flows. The results show that the northernmost strait connecting the ría with the Atlantic Ocean is a promising site for tidal energy tapping, in contrast with the energetically weaker estuary. On the basis of the average power density (APD), a 7.5 km2 region is identified in this strait as the most advantageous area to install tidal energy converters (TECs), with a total annual exergy of around 3865 MWh/m2. Similar analyses using only 14-day simulations change this value in ±16%, depending on whether the tidal cycle considered is apogean or perigean. The study contributes to enlarge the inventory of sites along the NW Spanish coast at which tidal stream energy can be potentially extracted.Peer ReviewedPostprint (author's final draft

Short-term morphodynamic changes in a fetch limited beach at the Ebro delta (Spain), under low wave-energy conditions

Sandy beaches in fetch-limited environments are protected from large ocean-generated swell waves, and fetch characteristics allow local wind-generated waves and currents to develop and drive the main morphodynamic processes. The morphodynamics of these low-energy beaches present a peculiar behaviour since there is not a dominant forcing mechanism inducing the beach changes. The main objective of this work is to describe and quantify the observed morphodynamic changes at the barred, quasi longshore-uniform beach of the Trabucador Bar at the Ebro Delta (Spain) under low-energy conditions. A nine-day field campaign was carried out within the framework of the European project FANS (Fluxes Across Narrow Shelves. The Ebro Delta Case) supported by the EC MAST-III Research Programme, (Contract No. MAS3-CT95-0037, DG12 – ESCY) and the measurements included a detailed topo-bathymetric surveying at the beginning and at the end of the campaign, video recordings covering the whole domain of the study area, surf zone waves and currents time series obtained at different positions and depths, nearshore pressure and horizontal velocities time series outside the surf zone. The results show that the beach underwent important longshore and cross-shore (the breaching of the submerged bar) morphodynamic changes under low-energy conditions. The observations suggest that the low-energy wave field and the beach profile played a key role in the generation of low frequency oscillations and rip currents that reshaped the whole study zone.Postprint (published version

Short-term morphodynamic changes in a fetch limited beach at the Ebro delta (Spain), under low wave-energy conditions

Sandy beaches in fetch-limited environments are protected from large ocean-generated swell waves, and fetch characteristics allow local wind-generated waves and currents to develop and drive the main morphodynamic processes. The morphodynamics of these low-energy beaches present a peculiar behaviour since there is not a dominant forcing mechanism inducing the beach changes. The main objective of this work is to describe and quantify the observed morphodynamic changes at the barred, quasi longshore-uniform beach of the Trabucador Bar at the Ebro Delta (Spain) under low-energy conditions. A nine-day field campaign was carried out within the framework of the European project FANS (Fluxes Across Narrow Shelves. The Ebro Delta Case) supported by the EC MAST-III Research Programme, (Contract No. MAS3-CT95-0037, DG12 – ESCY) and the measurements included a detailed topo-bathymetric surveying at the beginning and at the end of the campaign, video recordings covering the whole domain of the study area, surf zone waves and currents time series obtained at different positions and depths, nearshore pressure and horizontal velocities time series outside the surf zone. The results show that the beach underwent important longshore and cross-shore (the breaching of the submerged bar) morphodynamic changes under low-energy conditions. The observations suggest that the low-energy wave field and the beach profile played a key role in the generation of low frequency oscillations and rip currents that reshaped the whole study zone.Postprint (published version

Assessment of harbour inoperability and adaptation cost due to sea level rise: application to the port of Tangier-Med (Morocco)

This paper intends to assess the potential impacts of the future SLR on the operability of berthing structures and to estimate in monetary terms the adaptation costs to it. To do this, three scenarios of SLR are considered, two corresponding to the last assessment report of IPCC (RCP4.5 and RCP8.5) and the other being a high-end scenario (HES), with a low probability of occurrence but physically possible. The research is focused on the case study of Tangier-Med port, which is considered as an economic magnet for the northern region of Morocco and the centerpiece of the government strategy for port development. The results show that the operability of the port will be affected only under the HES and from 2090 onwards. However, by 2100, in this scenario all the docks would be affected, especially the service terminal and those dedicated to containers, hydrocarbons, vehicles and general cargo, in which the percentage of inoperability could exceed 30% of the time. This would lead to traffic losses of 1.9 million TEUS and more than 22 million tons of cargo by 2100 while the adaptation costs would exceed 40 million euros (in present monetary units).The work described in this publication was funded by the European Union's Seventh Framework Programme through the grant to the budget of the Collaborative Project RISES-AM-, Contract FP7-ENV-2013-two-stage-603396. The support of the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (Ref 2014SGR1253) is also acknowledged.Peer ReviewedPostprint (published version

Sistemes costaners i dinàmica litoral

Aquest capítol tracta de la projecció dels impactes de climes futurs per a trams vulnerables de la costa catalana. Al començament, s’hi revisa la geodiversitat de la costa en termes meteorològics i geològics. El ventall d’impactes que en resulta (sota climes presents i futurs) presenta uns nivells d’incertesa que s’han de considerar per a poder prendre decisions. L’anàlisi es basa en les projeccions del nivell mitjà del mar i en les característiques de l’onatge per a les famílies d’escenaris RCP (trajectòries de concentracions representatives). La projecció dels impactes d’erosió i inundació per a platges i d’agitació i ultrapassament per a ports permet determinar quin és el domini costaner sotmès a aquests impactes, i també quins seran els nivells de risc que es poden esperar en platges i ports. Les conclusions del capítol s’estructuren com un seguit d’actuacions seqüencials per a afavorir la sostenibilitat de la costa. Aquest «camí d’adaptació» permetrà d’assolir uns nivells de riscs presents i futurs explícits, que han de ser considerats per a les activitats socioeconòmiques de la zona litoral.Postprint (published version

Modelling the impact of climate change on harbour operability: the Barcelona port case study

Harbours are essential infrastructures for economic activity that are susceptible to impacts from climate change driven processes, like sea level rise (SLR), or alterations in wave patterns. In this paper, the impact of climate change on wave agitation in ports (oscillations due to wind waves) and, therefore, on port operability is analyzed. This is carried out through a numerical model suite, considering the RCP8.5 scenario to project changes in wave fields, and three values of SLR. The study is particularized for the port of Barcelona (NW Mediterranean), but the used methodology can be applied to other harbours. Results suggest that changes due only to waves will be minimal and with a general trend to slightly decrease wave agitation. On the contrary, the effect of SLR and the associated increase of water depth will favor the penetration of waves within the harbour, leading to a certain reduction of port operability, the magnitude of which will depend on the SLR value. However, the complexity of wave patterns within the harbours, due to multiple reflections of waves on port structures, implies that the reduction of operability strongly varies according to the position and orientation of the berthing zones inside the harbour.Peer ReviewedPostprint (author's final draft